Journal articles: 'Necrotroph'

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Shi, Gongjun, Zengcui Zhang, Timothy L. Friesen, Dina Raats, Tzion Fahima, Robert S. Brueggeman, Shunwen Lu, et al. "The hijacking of a receptor kinase–driven pathway by a wheat fungal pathogen leads to disease." Science Advances 2, no. 10 (October 2016): e1600822. http://dx.doi.org/10.1126/sciadv.1600822.

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Necrotrophic pathogens live and feed on dying tissue, but their interactions with plants are not well understood compared to biotrophic pathogens. The wheatSnn1gene confers susceptibility to strains of the necrotrophic pathogenParastagonospora nodorumthat produce the SnTox1 protein. We report the positional cloning ofSnn1, a member of the wall-associated kinase class of receptors, which are known to drive pathways for biotrophic pathogen resistance. Recognition of SnTox1 bySnn1activates programmed cell death, which allows this necrotroph to gain nutrients and sporulate. These results demonstrate that necrotrophic pathogens such asP. nodorumhijack host molecular pathways that are typically involved in resistance to biotrophic pathogens, revealing the complex nature of susceptibility and resistance in necrotrophic and biotrophic pathogen interactions with plants.

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McGrann, Graham R. D., Steven Miller, and Neil D. Havis. "The ENHANCED MAGNAPORTHE RESISTANCE 1 locus affects Ramularia leaf spot development in barley." European Journal of Plant Pathology 156, no. 1 (November 14, 2019): 123–32. http://dx.doi.org/10.1007/s10658-019-01869-x.

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AbstractRamularia leaf spot (RLS) is a newly-important disease of barley which is caused when the fungus Ramularia collo-cygni enters necrotrophic development during colonisation of the host. Mutant alleles at the barley MILDEW LOCUS O, mlo, locus confer broad spectrum durable resistance against the powdery mildew fungus, Blumeria graminis f. sp. hordei, but can enhance susceptibility to pathogens with necrotrophic development stages such as R. collo-cygni. Given the importance of mlo in spring barley breeding programmes, identifying loci that mitigate the effect of mlo-mediated susceptibility on necrotrophic disease development is an important target. Mutation of the ENHANCED MAGNAPORTHE 1 (emr1) locus which can affect mlo-associated disease susceptibility, leads to a reduction in RLS symptoms on barley leaves but does not reduce R. collo-cygni accumulation. The effect of emr1 on the transition of R. collo-cygni from endophyte to necrotroph may relate to changes in reactive oxygen species in mutant plants which show reduced sensitivity to chloroplastic superoxide induced cell death and has lower relative chlorophyll content compared to mlo plants.

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Laluk, Kristin, and Tesfaye Mengiste. "Necrotroph Attacks on Plants: Wanton Destruction or Covert Extortion?" Arabidopsis Book 8 (January 2010): e0136. http://dx.doi.org/10.1199/tab.0136.

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Liang, Xiaofei, and Jeffrey A. Rollins. "Mechanisms of Broad Host Range Necrotrophic Pathogenesis in Sclerotinia sclerotiorum." Phytopathology® 108, no. 10 (October 2018): 1128–40. http://dx.doi.org/10.1094/phyto-06-18-0197-rvw.

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Among necrotrophic fungi, Sclerotinia sclerotiorum is remarkable for its extremely broad host range and for its aggressive host tissue colonization. With full genome sequencing, transcriptomic analyses and the increasing pace of functional gene characterization, the factors underlying the basis of this broad host range necrotrophic pathogenesis are now being elucidated at a greater pace. Among these, genes have been characterized that are required for infection via compound appressoria in addition to genes associated with colonization that regulate oxalic acid (OA) production and OA catabolism. Moreover, virulence-related secretory proteins have been identified, among which are candidates for manipulating host activities apoplastically and cytoplasmically. Coupled with these mechanistic studies, cytological observations of the colonization process have blurred the heretofore clear-cut biotroph versus necrotroph boundary. In this review, we reexamine the cytology of S. sclerotiorum infection and put more recent molecular and genomic data into the context of this cytology. We propose a two-phase infection model in which the pathogen first evades, counteracts and subverts host basal defense reactions prior to killing and degrading host cells. Spatially, the pathogen may achieve this via the production of compatibility factors/effectors in compound appressoria, bulbous subcuticular hyphae, and primary invasive hyphae. By examining the nuances of this interaction, we hope to illuminate new classes of factors as targets to improve our understanding of broad host range necrotrophic pathogens and provide the basis for understanding corresponding host resistance.

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Craven, Kelly D., Heriberto Vélëz, Yangrae Cho, Christopher B. Lawrence, and Thomas K. Mitchell. "Anastomosis Is Required for Virulence of the Fungal Necrotroph Alternaria brassicicola." Eukaryotic Cell 7, no. 4 (February 29, 2008): 675–83. http://dx.doi.org/10.1128/ec.00423-07.

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ABSTRACTA fungal mycelium is typically composed of radially extending hyphal filaments interconnected by bridges created through anastomoses. These bridges facilitate the dissemination of nutrients, water, and signaling molecules throughout the colony. In this study, we used targeted gene deletion and nitrate utilization mutants of the cruciferous pathogenAlternaria brassicicolaand two closely related species to investigate hyphal fusion (anastomosis) and its role in the ability of fungi to cause disease. All eight of theA. brassicicolaisolates tested, as well asA. mimiculaandA. japonica, were capable of self-fusion, with two isolates ofA. brassicicolabeing capable of non-self-fusion. Disruption of the anastomosis gene homolog (Aso1) inA. brassicicolaresulted in both the loss of self-anastomosis and pathogenicity on cabbage. This finding, combined with our discovery that a previously described nonpathogenicA. brassicicolamutant defective for a mitogen-activated protein kinase gene (amk1) also lacked the capacity for self-anastomosis, suggests that self-anastomosis is associated with pathogenicity inA. brassicicola.

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Derbyshire, Mark C., and Sylvain Raffaele. "Till death do us pair: Co-evolution of plant–necrotroph interactions." Current Opinion in Plant Biology 76 (December 2023): 102457. http://dx.doi.org/10.1016/j.pbi.2023.102457.

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Sierota, Zbigniew, and Wojciech Grodzki. "Picea abies–Armillaria–Ips: A Strategy or Coincidence?" Forests 11, no. 9 (September 22, 2020): 1023. http://dx.doi.org/10.3390/f11091023.

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Norway spruce trees weakened by soil drought and progressive die-off of mycorrhizas in root systems become susceptible to infection by rhizomorphs of Armillaria spp. The developing mycelium of this necrotroph induces resin channels in wood, and the induced resin releases some volatile compounds which falsely signal bark beetles that it is safe to invade the host. As a result of the developing beetle outbreak, host trees die, becoming a long-term stock of substrate for the fungus in its saprotrophic stage. This hypothesis is discussed as a fungal survival strategy.

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Ederli, Luisa, Gianandrea Salerno, and Mara Quaglia. "In the tripartite combination Botrytis cinerea–Arabidopsis–Eurydema oleracea, the fungal pathogen alters the plant–insect interaction via jasmonic acid signalling activation and inducible plant-emitted volatiles." Journal of Plant Research 134, no. 3 (March 18, 2021): 523–33. http://dx.doi.org/10.1007/s10265-021-01273-9.

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AbstractIn ecosystems, plants are continuously challenged by combined stress conditions more than by a single biotic or abiotic factor. Consequently, in recent years studies on plant relationships with multiple stresses have aroused increasing interest. Here, the impact of inoculation with fungal pathogens with different lifestyles on Arabidopsis plants response to the following infestation with the invasive crop pest Eurydema oleracea was investigated. In particular, as fungal pathogens the necrotroph Botrytis cinerea and the biotroph Golovinomyces orontii were used. Plants exposed to B. cinerea, but not to G. orontii, showed reduced herbivore feeding damage. This difference was associated to different hormonal pathways triggered by the pathogens: G. orontii only induced the salicylate-mediated pathway, while B. cinerea stimulated also the jasmonate-dependent signalling, which persisted for a long time providing a long-term defence to further herbivore attack. In particular, the lower susceptibility of B. cinerea-infected Arabidopsis plants to E. oleracea was related to the stimulation of the JA-induced pathway on the production of plant volatile compounds, since treatment with VOCs emitted by B. cinerea inoculated plants inhibited both insect plant choice and feeding damage. These results indicate that necrotrophic plant pathogenic fungi modulate host volatile emission, thus affecting plant response to subsequent insect, thereby increasing the knowledge on tripartite plant–microbe–insect interactions in nature.

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Kumari, Anita, Abhijeet Ghatak, and Srinivasaraghavan A. "Biochemical responses of soil-borne necrotroph Sclerotium rolfsii during the pathogenesis on chickpea." International Journal of Chemical Studies 8, no. 1 (January 1, 2020): 2596–601. http://dx.doi.org/10.22271/chemi.2020.v8.i1an.8661.

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Bailey, Bryan A., Shahin S. Ali, Mary D. Strem, and Lyndel W. Meinhardt. "Morphological variants of Moniliophthora roreri on artificial media and the biotroph/necrotroph shift." Fungal Biology 122, no. 7 (July 2018): 701–16. http://dx.doi.org/10.1016/j.funbio.2018.03.003.

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Dubey, Manish K., Milind H. Gajbhiye, and Ram S. Upadhyay. "Achlya bisexualis (Achlyaceae, Saprolegniales, Oomycota) – A new record for India." Nova Hedwigia 111, no. 1 (August 1, 2020): 101–14. http://dx.doi.org/10.1127/nova_hedwigia/2020/0589.

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In the present report, Achlya bisexualis Coker and Couch is isolated, described and illustrated based on morpho-physiological characteristics and molecular analysis. The oogonial thallus of this dioecious (heterothallic) species is mainly recognized by the presence of predominantly spherical or pyriform gemmae and spherical or obpyriform oogonia with non-maturing oospores. The isolated specimen was identified by sequences comparison of the D1/D2 domains of the LSU and ITS-rDNA. To the best of our knowledge, this is the first confirmed record in India of Achlya bisexualis, known in the literature as a parasite or necrotroph. Besides, neither any species of genus Achlya has previously been subjected to molecular evaluation from India.

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Boyarkina, S. V., Yu V. Omelichkina, O. D. Volkova, A. G. Enikeev, V. V. Verkhoturov, and T. N. Shafikova. "RESPONSE OF NICOTIANA TABACUM ON THE IMPACT OF BIOTROPH CLAVIBACTER MICHIGANENSIS AND NECROTROPH PECTOBACTERIUM CAROTOVORUM." Proceedings of universities. Applied chemistry and biotechnology 6, no. 3 (2016): 42–49. http://dx.doi.org/10.21285/2227-2925-2016-6-3-42-49.

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13

Willoughby, L. G., and R. J. Roberts. "Occurrence of the sewage fungus Leptomitus lacteus, a necrotroph on perch (Perca fluviatilis), in Windermere." Mycological Research 95, no. 6 (June 1991): 755–58. http://dx.doi.org/10.1016/s0953-7562(09)80827-7.

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Sarkar, Tuhin Subhra, Pranjal Biswas, Subrata Kumar Ghosh, and Sanjay Ghosh. "Nitric Oxide Production by Necrotrophic Pathogen Macrophomina phaseolina and the Host Plant in Charcoal Rot Disease of Jute: Complexity of the Interplay between Necrotroph–Host Plant Interactions." PLoS ONE 9, no. 9 (September 10, 2014): e107348. http://dx.doi.org/10.1371/journal.pone.0107348.

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Akhtar, Nishar, Shahina Perween Shahina Perween2, Abdul Ansari, and Md Ahmad. "Life style of fungi from Biotrophy to Necrotrophy and Saprotrophy." International Journal of Agricultural and Applied Sciences 1, no. 1 (June 30, 2020): 92–102. http://dx.doi.org/10.52804/ijaas2020.1118.

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Plant pathogenic fungi causes’ economic menace to crop production throughout the world. On the basis of their life styles they may be classified as biotrophs, hemibiotrophs and necrotrophs. For biotrophs it is mandatory to thrive on living host cell and tissues and often found to secrete a little amount of cell wall degrading enzymes and certain effector molecules for suppressing plant host defense mechanism. Necrotrophs survive on dead host cell and tissues which are killed by them before or during infection. Hemibiotrophs in their early stage of life behave as biotrophs and become necrotrophs on later. This article represents the evolution of biotrophs, interaction of biotrophs, hemibiotrophs and necrotrophs with their host plant and continuum of life styles from biotrophy, through to necrotrophy and ultimately to saprotrophy.

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Jeffries, Peter. "Biology and ecology of mycoparasitism." Canadian Journal of Botany 73, S1 (December 31, 1995): 1284–90. http://dx.doi.org/10.1139/b95-389.

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The term mycoparasitism applies strictly to those relationships in which one living fungus acts as a nutrient source for another, but fungicolous relationships may also be included in which nutrient exchange has not been shown. Fungicolous fungi have a constant but indeterminate association with another fungus, and it can be difficult to demonstrate a true parasitic relationship. Mycoparasitic relationships can be necrotrophic or biotrophic, and can be classified on the basis of the host–parasite interface as contact necrotrophs, invasive necrotrophs, haustorial biotrophs, intracellular biotrophs, or fusion biotrophs depending on the intimacy of the relationship. In natural ecosystems, it is proposed that mycoparasitic relationships play an important role in the development of fungal communities. Two specific examples have been chosen to illustrate the general principles of mycoparasitism: the necrotrophic invasion of spores of arbuscular mycorrhizal fungi and the biotrophic invasion of mucoralean hosts by haustorial mycoparasites. Key words: mycoparasitism, fungicolous fungi, arbuscular mycorrhizal fungi, fungal ecology.

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Liang, Kuan, Jianbin Lan, Baoquan Wang, Yuanyuan Liu, Qi Lu, and Pu Liu. "High-Quality Genome Resource of the Pathogen of Botryosphaeria dothidea Causing Kiwifruit Soft Rot." PhytoFrontiers™ 1, no. 2 (April 2021): 123–25. http://dx.doi.org/10.1094/phytofr-07-20-0006-a.

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Kiwifruit soft rot caused by the fungal pathogen Botryosphaeria dothidea is a serious disease in kiwifruit-growing regions worldwide. In this study, we reported the high-quality genome sequence of the highly virulent B. dothidea strain PTZ1 using PacBio Sequel techniques. In total, 100.87 million clean reads with mean read length of 9,871 bp were obtained. De novo assembly resulted in 28 contigs with a total size of 44.45 Mb. The GC content of the genome was 54.59%. Furthermore, genes related to specific virulence of the strain were identified, including 259 fungal cytochrome P450s, 550 carbohydrate-active enzymes, 860 secretory proteins, and 1,182 pathogen–host interactions related proteins. The genome is a useful resource to serve as a reference to facilitate the analysis of B. dothidea isolates and comparative genomic studies of the necrotroph pathogens. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

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Azevedo, H., T. Lino-Neto, and R. M. Tavares. "The Necrotroph Botrytis cinerea Induces a Non-Host Type II Resistance Mechanism in Pinus pinaster Suspension-Cultured Cells." Plant and Cell Physiology 49, no. 3 (January 9, 2008): 386–95. http://dx.doi.org/10.1093/pcp/pcn015.

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Goodwin, Paul H., and Grace Y. J. Chen. "Expression of a glycogen synthase protein kinase homolog from Colletotrichum gloeosporioides f.sp. malvae during infection of Malva pusilla." Canadian Journal of Microbiology 48, no. 11 (November 1, 2002): 1035–39. http://dx.doi.org/10.1139/w02-102.

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The potential role of a GSK3 protein kinase homolog, cggsk, was examined from Colletotrichum gloeosporioides f.sp. malvae, a fungal pathogen of Malva pusilla. A peak in cggsk expression relative to a constitutively expressed fungal actin gene occurred during host penetration and was followed by much lower expression levels during subsequent biotrophic and necrotrophic growth in host tissue. The peak level of cggsk expression observed during penetration was 21-fold greater than that during necrotrophic growth. Expression of cggsk showed small but reproducible changes during growth in culture; however, the levels were always similar to that during necrotrophic growth in the host. One possible role for cggsk could be to coordinate fungal development during host penetration.Key words: appressorium, biotrophy, GSK3, hemibiotrophy, necrotrophy.

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Melton, Rachel E., Lynda M. Flegg, James K. M. Brown, Richard P. Oliver, Michael J. Daniels, and Anne E. Osbourn. "Heterologous Expression of Septoria lycopersici Tomatinase in Cladosporium fulvum: Effects on Compatible and Incompatible Interactions with Tomato Seedlings." Molecular Plant-Microbe Interactions® 11, no. 3 (March 1998): 228–36. http://dx.doi.org/10.1094/mpmi.1998.11.3.228.

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The anti-fungal, steroidal, glycoalkaloid saponin, α-tomatine, is present in uninfected tomato plants in substantial concentrations, and may contribute to the protection of tomato plants against attack by phytopathogenic fungi. In general, successful fungal pathogens of tomato are more resistant to α-tomatine in vitro than fungi that do not infect this plant. For a number of tomato pathogens, this resistance has been associated with the ability to detoxify α-tomatine through the action of enzymes known as tomatinases. In contrast, the biotrophic tomato pathogen Cladosporium fulvum is sensitive to α-tomatine and is unable to detoxify this saponin. This paper describes the effects of heterologous expression of the cDNA encoding tomatinase from the necrotroph Septoria lycopersici in two different physiological races of C. fulvum. Tomatinase-producing C. fulvum transformants showed increased sporulation on cotyledons of susceptible tomato lines. They also caused more extensive infection of seedlings of resistant tomato lines. Thus, α-tomatine may contribute to the ability of tomato to restrict the growth of C. fulvum in both compatible and incompatible interactions.

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Lorang, Jennifer. "Necrotrophic Exploitation and Subversion of Plant Defense: A Lifestyle or Just a Phase, and Implications in Breeding Resistance." Phytopathology® 109, no. 3 (March 2019): 332–46. http://dx.doi.org/10.1094/phyto-09-18-0334-ia.

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Breeding disease-resistant plants is a critical, environmentally friendly component of any strategy to sustainably feed and clothe the 9.8 billion people expected to live on Earth by 2050. Here, I review current literature detailing plant defense responses as they relate to diverse biological outcomes; disease resistance, susceptibility, and establishment of mutualistic plant–microbial relationships. Of particular interest is the degree to which these outcomes are a function of plant-associated microorganisms’ lifestyles; biotrophic, hemibiotrophic, necrotrophic, or mutualistic. For the sake of brevity, necrotrophic pathogens and the necrotrophic phase of pathogenicity are emphasized in this review, with special attention given to the host-specific pathogens that exploit defense. Defense responses related to generalist necrotrophs and mutualists are discussed in the context of excellent reviews by others. In addition, host evolutionary trade-offs of disease resistance with other desirable traits are considered in the context of breeding for durable disease resistance.

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Beccaccioli, Marzia, Manuel Salustri, Valeria Scala, Matteo Ludovici, Andrea Cacciotti, Simone D’Angeli, Daren W. Brown, and Massimo Reverberi. "The Effect of Fusarium verticillioides Fumonisins on Fatty Acids, Sphingolipids, and Oxylipins in Maize Germlings." International Journal of Molecular Sciences 22, no. 5 (February 28, 2021): 2435. http://dx.doi.org/10.3390/ijms22052435.

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Fusarium verticillioides causes multiple diseases of Zea mays (maize) including ear and seedling rots, contaminates seeds and seed products worldwide with toxic chemicals called fumonisins. The role of fumonisins in disease is unclear because, although they are not required for ear rot, they are required for seedling diseases. Disease symptoms may be due to the ability of fumonisins to inhibit ceramide synthase activity, the expected cause of lipids (fatty acids, oxylipins, and sphingolipids) alteration in infected plants. In this study, we explored the impact of fumonisins on fatty acid, oxylipin, and sphingolipid levels in planta and how these changes affect F. verticillioides growth in maize. The identity and levels of principal fatty acids, oxylipins, and over 50 sphingolipids were evaluated by chromatography followed by mass spectrometry in maize infected with an F. verticillioides fumonisin-producing wild-type strain and a fumonisin-deficient mutant, after different periods of growth. Plant hormones associated with defense responses, i.e., salicylic and jasmonic acid, were also evaluated. We suggest that fumonisins produced by F. verticillioides alter maize lipid metabolism, which help switch fungal growth from a relatively harmless endophyte to a destructive necrotroph.

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Bennett, Sarita Jane, Ashmita Rijal Lamichhane, Linda L. Thomson, King Yin Lui, and Pippa J. Michael. "Impact of Fungicide Application and Host Genotype on Susceptibility of Brassica napus to Sclerotinia Stem Rot across the South-Western Australian Grain Belt: A Genotype × Environment × Management Study." Agronomy 11, no. 6 (June 8, 2021): 1170. http://dx.doi.org/10.3390/agronomy11061170.

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Sclerotinia stem rot (SSR), caused by the necrotroph Sclerotinia sclerotiorum Lib. (de Bary), is a major disease of canola in Australia, greatly reducing yields in high infection years. This study investigated genotype by environment by management interactions at 25 sites across the south-west Australian grainbelt from 2017 to 2020. Up to 10 canola varieties were grown each year with +/− fungicide application at 30% flowering. Disease incidence was low, with less than 20% infection recorded across most sites. Most variation in yield occurred between sites, rather than by management or variety, due to the environmental differences between the sites. Petal assays were found to be a poor indicator of later disease severity, suggesting the winter growing season in south-west Australia does not have reliable conducive conditions for disease development following petal drop in canola. The Additive Main Effects and Multiplicative Interaction model (AMMI) indicated that the open-pollinated varieties were broadly adapted and stable when fungicide was applied but became unstable with no fungicide, indicating SSR has a significant impact on yield when disease incidence is higher. This study highlights that further research is necessary to determine disease thresholds that lead to significant yield loss.

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Kariola, Tarja, Tiina A. Palomäki, Günter Brader, and E. Tapio Palva. "Erwinia carotovora subsp. carotovora and Erwinia-Derived Elicitors HrpN and PehA Trigger Distinct but Interacting Defense Responses and Cell Death in Arabidopsis." Molecular Plant-Microbe Interactions® 16, no. 3 (March 2003): 179–87. http://dx.doi.org/10.1094/mpmi.2003.16.3.179.

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We have used an hrp-positive strain of the soft rot pathogen Erwinia carotovora subsp. carotovora to elucidate plant responses to this bacterial necrotroph. Purified virulence determinants, harpin (HrpN) and polygalacturonase (PehA), were used as tools to facilitate this analysis. We show that HrpN elicits lesion formation in Arabidopsis and tobacco and triggers systemic resistance in Arabidopsis. Establishment of resistance is accompanied by the expression of salicylic acid (SA)-dependent, but also jasmonate/ethylene (JA/ET)-dependent, marker genes PR1 and PDF1.2, respectively, suggesting that both SA-dependent and JA/ET-dependent defense pathways are activated. Use of pathway-specific mutants and transgenic NahG plants show that both pathways are required for the induction of resistance. Arabidopsis plants treated simultaneously with both elictors PehA, known to trigger only JA/ET-dependent defense signaling, and HrpN react with accelerated and enhanced induction of the marker genes PR1 and PDF1.2 both locally and systemically. This mutual amplification of defense gene expression involves both SA-dependent and JA/ET-dependent defense signaling. The two elicitors produced by E. carotovora subsp. carotovora also cooperate in triggering increased production of superoxide and lesion formation.

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Chatterjee, Madhuvanti, Mrinmoy Mazumder, and Debabrata Basu. "Functional Analysis of the Promoter of a Glycosyl Hydrolase Gene Induced in Resistant Sinapis alba by Alternaria brassicicola." Phytopathology® 103, no. 8 (August 2013): 841–50. http://dx.doi.org/10.1094/phyto-11-12-0303-r.

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A putative family 3 glycosyl hydrolase (GH) gene showed significant differential expression in resistant Sinapis alba, compared with the susceptible Brassica juncea, as part of the initial responses during interaction with the necrotroph Alternaria brassicicola. To understand the mechanism of induction, the promoter was isolated and deletion analysis carried out. All the promoter fragments were fused with the β-glucuronidase gene and the expressions were studied in stable B. juncea transgenics and transiently transformed Nicotiana tabacum. Analysis of the expression of the promoter showed the presence of functional abscisic acid (ABA)-, jasmonic acid (JA)-, and salicylic acid (SA)-responsive cis elements. Interestingly, the promoter was found to be induced in both S. alba and B. juncea upon challenge with A. brassicicola but, in S. alba, SA had an inhibitory effect on the pathogen-induced expression of the gene whereas, in B. juncea, SA did not have any negative effect. Therefore, the SA-mediated inhibition in S. alba indicates that the induction is probably through JA or ABA signaling. The difference in the mechanism of induction of the same promoter in the resistant and susceptible plants is probably due to the differential hormonal responses initiated upon challenge with A. brassicicola.

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De Vallée, Amelie, Jean-William Dupuy, Christine Moriscot, Benoit Gallet, Solène Vanderperre, Gaëtan Guignard, Christine Rascle, et al. "Extracellular Vesicles of the Plant Pathogen Botrytis cinerea." Journal of Fungi 9, no. 4 (April 20, 2023): 495. http://dx.doi.org/10.3390/jof9040495.

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Fungal secretomes are known to contain a multitude of components involved in nutrition, cell growth or biotic interactions. Recently, extra-cellular vesicles have been identified in a few fungal species. Here, we used a multidisciplinary approach to identify and characterize extracellular vesicles produced by the plant necrotroph Botrytis cinerea. Transmission electron microscopy of infectious hyphae and hyphae grown in vitro revealed extracellular vesicles of various sizes and densities. Electron tomography showed the co-existence of ovoid and tubular vesicles and pointed to their release via the fusion of multi-vesicular bodies with the cell plasma membrane. The isolation of these vesicles and exploration of their protein content using mass spectrometry led to the identification of soluble and membrane proteins involved in transport, metabolism, cell wall synthesis and remodeling, proteostasis, oxidoreduction and traffic. Confocal microscopy highlighted the capacity of fluorescently labeled vesicles to target cells of B. cinerea, cells of the fungus Fusarium graminearum, and onion epidermal cells but not yeast cells. In addition, a specific positive effect of these vesicles on the growth of B. cinerea was quantified. Altogether, this study broadens our view on the secretion capacity of B. cinerea and its cell-to-cell communication.

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Wytinck, Nick, Dylan J. Ziegler, Philip L. Walker, Daniel S. Sullivan, Kirsten T. Biggar, Deirdre Khan, Solihu K. Sakariyahu, Olivia Wilkins, Steve Whyard, and Mark F. Belmonte. "Host induced gene silencing of the Sclerotinia sclerotiorum ABHYDROLASE-3 gene reduces disease severity in Brassica napus." PLOS ONE 17, no. 8 (August 26, 2022): e0261102. http://dx.doi.org/10.1371/journal.pone.0261102.

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Sclerotinia sclerotiorum is a pathogenic fungus that infects hundreds of crop species, causing extensive yield loss every year. Chemical fungicides are used to control this phytopathogen, but with concerns about increasing resistance and impacts on non-target species, there is a need to develop alternative control measures. In the present study, we engineered Brassica napus to constitutively express a hairpin (hp)RNA molecule to silence ABHYRDOLASE-3 in S. sclerotiorum. We demonstrate the potential for Host Induced Gene Silencing (HIGS) to protect B. napus from S. sclerotiorum using leaf, stem and whole plant infection assays. The interaction between the transgenic host plant and invading pathogen was further characterized at the molecular level using dual-RNA sequencing and at the anatomical level through microscopy to understand the processes and possible mechanisms leading to increased tolerance to this damaging necrotroph. We observed significant shifts in the expression of genes relating to plant defense as well as cellular differences in the form of structural barriers around the site of infection in the HIGS-protected plants. Our results provide proof-of-concept that HIGS is an effective means of limiting damage caused by S. sclerotiorum to the plant and demonstrates the utility of this biotechnology in the development of resistance against fungal pathogens.

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Passos, J. L., L. C. A. Barbosa, A. J. Demuner, R. W. Barreto, B. King-Diaz, and B. Lotina-Hennsen. "Effects of Corynespora cassiicola on Lantana camara." Planta Daninha 28, no. 2 (June 2010): 229–37. http://dx.doi.org/10.1590/s0100-83582010000200001.

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The present study combines the examination of toxins produced by C. cassiicola and the effects of the fungus colonization on L. camara. C. cassiicola was cultivated on solid media and the crude extracts CAE and CE were produced. Both extracts were submitted to a seed germination and growth assay utilizing Physalis ixocarpa, Trifolium alexandrinum, Lolium multiflorum and Amaranthus hypochodriacus. The effect of the extracts on the ATP-synthesis in isolated spinach chloroplasts was also tested. Bioassay guided chromatographic fractionation identified the most active extract (CAE). From this extract ergosta-4,6,8(14),22-tetraen-3-one (C1) and fatty acids were isolated. The C1 compound reduce ATP synthesis in isolated spinach chloroplasts. The interference of fatty acids with ATP synthesis and also with weed growth provides one explanation of the phytogrowth-inhibitory properties of such fungal extracts. Histological observations involving fungus-plant interaction were made on L. camara plants inoculated with C. cassiicola conidia suspension. After inoculations, fragments of the leaf blades were prepared for observation by light and scanning electron microscopy. Fungal colonization of Lantana camara was typical of a necrotroph and penetration initiated a hypersensitive response. L. camara reacted to the pathogen penetration through thickening of the epidermis walls, cytoplasm granulation and a cicatrisation tissue.

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Rodríguez-Pires, Silvia, Paloma Melgarejo, Antonieta De Cal, and Eduardo A. Espeso. "Pectin as Carbon Source for Monilinia laxa Exoproteome and Expression Profiles of Related Genes." Molecular Plant-Microbe Interactions® 33, no. 9 (September 2020): 1116–28. http://dx.doi.org/10.1094/mpmi-01-20-0019-r.

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Pectin, as part of the fruit cell wall, can be degraded by brown rot fungi by coordinating the production, secretion, and action of extracellular enzymes. In this study, pectin utilization by the necrotroph Monilinia laxa 8L was studied by in vitro and in silico approaches. A total of 403 genes encoding carbohydrate-active enzymes (CAZymes) were identified, including 38 coding a predicted pectin-degrading activity. Analyzing the differences between M. laxa 8L exoproteomes in media containing glucose and pectin as sole carbon sources, we identified 107 pectin-specific proteins, among them, 64.48% harbor a classical secretory activity, including 42 CAZymes and six pectin-degrading proteins. Analyzing the gene-expression patterns of some pectinase families revealed their possible sequential action in pectin disassembly. We found, in vitro, an early pectin-dependent induction of MlRGAE1, MlPG1, and three members of the rhamnosidase family (MlαRHA2, MlαRHA3, and MlαRHA6) and late response of MlPG2 and MlPNL3. M. laxa 8L has the ability to use both pectin and byproducts as carbon sources, based on a functional pectinolytic machinery encoded in its genome, subjected to pectin-dependent regulation and appropriate secretion mechanisms of these pectinolytic enzymes. Differences in the secretion and transcription profile of M. laxa 8L provided insights into the different mechanisms that contribute to brown rot development.

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De Vleesschauwer, David, Pierre Cornelis, and Monica Höfte. "Redox-Active Pyocyanin Secreted by Pseudomonas aeruginosa 7NSK2 Triggers Systemic Resistance to Magnaporthe grisea but Enhances Rhizoctonia solani Susceptibility in Rice." Molecular Plant-Microbe Interactions® 19, no. 12 (December 2006): 1406–19. http://dx.doi.org/10.1094/mpmi-19-1406.

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Pseudomonas aeruginosa 7NSK2 induces resistance in dicots through a synergistic interaction of the phenazine pyocyanin and the salicylic acid-derivative pyochelin. Root inoculation of the monocot model rice with 7NSK2 partially protected leaves against blast disease (Magnaporthe grisea) but failed to consistently reduce sheath blight (Rhizoctonia solani). Only mutations interfering with pyocyanin production led to a significant decrease in induced systemic resistance (ISR) to M. grisea, and in trans complementation for pyocyanin production restored the ability to elicit ISR. Intriguingly, pyocyanin-deficient mutants, unlike the wild type, triggered ISR against R. solani. Hence, bacterial pyocyanin plays a differential role in 7NSK2-mediated ISR in rice. Application of purified pyocyanin to hydroponically grown rice seedlings increased H2O2 levels locally on the root surface as well as a biphasic H2O2 generation pattern in distal leaves. Co-application of pyocyanin and the antioxidant sodium ascorbate alleviated the opposite effects of pyocyanin on rice blast and sheath blight development, suggesting that the differential effectiveness of pyocyanin with respect to 7NSK2-triggered ISR is mediated by transiently elevated H2O2 levels in planta. The cumulative results suggest that reactive oxygen species act as a double-edged sword in the interaction of rice with the hemibiotroph M. grisea and the necrotroph R. solani.

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Brader, Günter, Armin Djamei, Markus Teige, E. Tapio Palva, and Heribert Hirt. "The MAP Kinase Kinase MKK2 Affects Disease Resistance in Arabidopsis." Molecular Plant-Microbe Interactions® 20, no. 5 (May 2007): 589–96. http://dx.doi.org/10.1094/mpmi-20-5-0589.

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The Arabidopsis mitogen-activated protein kinase (MAPK) kinase 2 (MKK2) was shown to mediate cold and salt stress responses through activation of the two MAP kinases MPK4 and MPK6. Transcriptome analysis of plants expressing constitutively active MKK2 (MKK2-EE plants) showed altered expression of genes induced by abiotic stresses but also a significant number of genes involved in defense responses. Both MPK4 and MPK6 became rapidly activated upon Pseudomonas syringae pv. tomato DC3000 infection and MKK2-EE plants showed enhanced levels of MPK4 activation. Although MKK2-EE plants shared enhanced expression of genes encoding enzymes of ethylene (ET) and jasmonic acid (JA) synthesis, ET, JA, and salicylic acid (SA) levels did not differ dramatically from those of wild-type or mkk2-null plants under ambient growth conditions. Upon P. syringae pv. tomato DC3000 infection, however, MKK2-EE plants showed reduced increases of JA and SA levels. These results indicate that MKK2 is involved in regulating hormone levels in response to pathogens. MKK2-EE plants were more resistant to infection by P. syringae pv. tomato DC3000 and Erwinia carotovora subsp. carotovora, but showed enhanced sensitivity to the fungal necrotroph Alternaria brassicicola. Our data indicate that MKK2 plays a role in abiotic stress tolerance and plant disease resistance.

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Loehrer, Marco, Caspar Langenbach, Katharina Goellner, Uwe Conrath, and Ulrich Schaffrath. "Characterization of Nonhost Resistance of Arabidopsis to the Asian Soybean Rust." Molecular Plant-Microbe Interactions® 21, no. 11 (November 2008): 1421–30. http://dx.doi.org/10.1094/mpmi-21-11-1421.

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Asian soybean rust (ASR), caused by Phakopsora pachyrhizi, is a devastating disease of soybean. We report the use of the nonhost plant Arabidopsis thaliana to identify the genetic basis of resistance to P. pachyrhizi. Upon attack by P. pachyrhizi, epidermal cells of wild-type Arabidopsis accumulated H2O2, which likely orchestrates the frequently observed epidermal cell death. However, even when epidermal cell death occurred, fungal hyphae grew on and infection was terminated at the mesophyll boundary. These events were associated with expression of PDF1.2, suggesting that P. pachyrhizi, an ostensible biotroph, mimics aspects of a necrotroph. Extensive colonization of the mesophyll occurred in Arabidopsis pen mutants with defective penetration resistance. Although haustoria were found occasionally in mesophyll cells, the successful establishment of biotrophy failed, as evidenced by the cessation of fungal growth. Double mutants affected in either jasmonic acid or salicylic acid signaling in the pen3-1 background revealed the involvement of both pathways in nonhost resistance (NHR) of Arabidopsis to P. pachyrhizi. Interestingly, expression of AtNHL10, a gene that is expressed in tissue undergoing the hypersensitive response, was only triggered in infected pen3-1 mutants. Thus, a suppression of P. pachyrhizi–derived effectors by PEN3 can be inferred. Our results demonstrate that Arabidopsis can be used to study mechanisms of NHR to ASR.

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Macioszek, Violetta Katarzyna, Tomasz Jęcz, Iwona Ciereszko, and Andrzej Kiejstut Kononowicz. "Jasmonic Acid as a Mediator in Plant Response to Necrotrophic Fungi." Cells 12, no. 7 (March 27, 2023): 1027. http://dx.doi.org/10.3390/cells12071027.

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Jasmonic acid (JA) and its derivatives, all named jasmonates, are the simplest phytohormones which regulate multifarious plant physiological processes including development, growth and defense responses to various abiotic and biotic stress factors. Moreover, jasmonate plays an important mediator’s role during plant interactions with necrotrophic oomycetes and fungi. Over the last 20 years of research on physiology and genetics of plant JA-dependent responses to pathogens and herbivorous insects, beginning from the discovery of the JA co-receptor CORONATINE INSENSITIVE1 (COI1), research has speeded up in gathering new knowledge on the complexity of plant innate immunity signaling. It has been observed that biosynthesis and accumulation of jasmonates are induced specifically in plants resistant to necrotrophic fungi (and also hemibiotrophs) such as mostly investigated model ones, i.e., Botrytis cinerea, Alternaria brassicicola or Sclerotinia sclerotiorum. However, it has to be emphasized that the activation of JA-dependent responses takes place also during susceptible interactions of plants with necrotrophic fungi. Nevertheless, many steps of JA function and signaling in plant resistance and susceptibility to necrotrophs still remain obscure. The purpose of this review is to highlight and summarize the main findings on selected steps of JA biosynthesis, perception and regulation in the context of plant defense responses to necrotrophic fungal pathogens.

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Mansfield, J., I. Brown, and M. Papp‐Rupar. "Life at the edge – the cytology and physiology of the biotroph to necrotroph transition in Hymenoscyphus fraxineus during lesion formation in ash." Plant Pathology 68, no. 5 (April 14, 2019): 908–20. http://dx.doi.org/10.1111/ppa.13014.

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Temmerman, R., H. Vervaeren, B. Noseda, N. Boon, and W. Verstraete. "Necrotrophic Growth of Legionella pneumophila." Applied and Environmental Microbiology 72, no. 6 (June 2006): 4323–28. http://dx.doi.org/10.1128/aem.00070-06.

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ABSTRACT This study examined whether Legionella pneumophila is able to thrive on heat-killed microbial cells (necrotrophy) present in biofilms or heat-treated water systems. Quantification by means of plate counting, real-time PCR, and flow cytometry demonstrated necrotrophic growth of L. pneumophila in water after 96 h, when at least 100 dead cells are available to one L. pneumophila cell. Compared to the starting concentration of L. pneumophila, the maximum observed necrotrophic growth was 1.89 log units for real-time PCR and 1.49 log units for plate counting. The average growth was 1.57 ï¿½ 0.32 log units (n = 5) for real-time PCR and 1.14 ï¿½ 0.35 log units (n = 5) for plate counting. Viability staining and flow cytometry showed that the fraction of living cells in the L. pneumophila population rose from the initial 54% to 82% after 96 h. Growth was measured on heat-killed Pseudomonas putida, Escherichia coli, Acanthamoeba castellanii, Saccharomyces boulardii, and a biofilm sample. Gram-positive organisms did not result in significant growth of L. pneumophila, probably due to their robust cell wall structure. Although necrotrophy showed lower growth yields compared to replication within protozoan hosts, these findings indicate that it may be of major importance in the environmental persistence of L. pneumophila. Techniques aimed at the elimination of protozoa or biofilm from water systems will not necessarily result in a subsequent removal of L. pneumophila unless the formation of dead microbial cells is minimized.

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Rahman, Taha Abd El, Mohamed El Oirdi, Rocio Gonzalez-Lamothe, and Kamal Bouarab. "Necrotrophic Pathogens Use the Salicylic Acid Signaling Pathway to Promote Disease Development in Tomato." Molecular Plant-Microbe Interactions® 25, no. 12 (December 2012): 1584–93. http://dx.doi.org/10.1094/mpmi-07-12-0187-r.

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Plants use different immune pathways to combat pathogens. The activation of the jasmonic acid (JA)-signaling pathway is required for resistance against necrotrophic pathogens; however, to combat biotrophic pathogens, the plants activate mainly the salicylic acid (SA)-signaling pathway. SA can antagonize JA signaling and vice versa. NPR1 (noninducible pathogenesis-related 1) is considered a master regulator of SA signaling. NPR1 interacts with TGA transcription factors, ultimately leading to the activation of SA-dependent responses. SA has been shown to promote disease development caused by the necrotrophic pathogen Botrytis cinerea through NPR1, by suppressing the expression of two JA-dependent defense genes, proteinase inhibitors I and II. We show here that the transcription factor TGA1.a contributes to disease development caused by B. cinerea in tomato by suppressing the expression of proteinase inhibitors I and II. Finally, we present evidence that the SA-signaling pathway contributes to disease development caused by another necrotrophic pathogen, Alternaria solani, in tomato. Disease development promoted by SA through NPR1 requires the TGA1.a transcription factor. These data highlight how necrotrophs manipulate the SA-signaling pathway to promote their disease in tomato.

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Nováková, Miroslava, Vladimír Šašek, Petre I. Dobrev, Olga Valentová, and Lenka Burketová. "Plant hormones in defense response of Brassica napus to Sclerotinia sclerotiorum – Reassessing the role of salicylic acid in the interaction with a necrotroph." Plant Physiology and Biochemistry 80 (July 2014): 308–17. http://dx.doi.org/10.1016/j.plaphy.2014.04.019.

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Vicedo, Begonya, Víctor Flors, María de la O Leyva, Ivan Finiti, Zhana Kravchuk, María Dolores Real, Pilar García-Agustín, and Carmen González-Bosch. "Hexanoic Acid-Induced Resistance Against Botrytis cinerea in Tomato Plants." Molecular Plant-Microbe Interactions® 22, no. 11 (November 2009): 1455–65. http://dx.doi.org/10.1094/mpmi-22-11-1455.

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We have demonstrated that root treatment with hexanoic acid protects tomato plants against Botrytis cinerea. Hexanoic acid-induced resistance (Hx-IR) was blocked in the jasmonic acid (JA)-insensitive mutant jai1 (a coi1 homolog) and in the abscisic acid (ABA)-deficient mutant flacca (flc). Upon infection, the LoxD gene as well as the oxylipin 12-oxo-phytodienoic acid and the bioactive molecule JA-Ile were clearly induced in treated plants. However, the basal ABA levels were not altered. Hexanoic acid primed callose deposition against B. cinerea in a cultivar-dependent manner. Treated plants from Ailsa Craig, Moneymaker, and Rheinlands Ruhm showed increased callose deposition but not from Castlemart. Hexanoic acid did not prime callose accumulation in flc plants upon B. cinerea infection; therefore, ABA could act as a positive regulator of Hx-IR by enhancing callose deposition. Furthermore, although hexanoic acid protected the JA-deficient mutant defensless1 (def1), the priming for callose was higher than in the wild type. This suggests a link between JA and callose deposition in tomato. Hence, the obtained results support the idea that callose, oxylipins, and the JA-signaling pathway are involved in Hx-IR against B. cinerea. Moreover our data support the relevance of JA-signaling for basal defense against this necrotroph in tomato. Hexanoic acid also protected against Pseudomonas syringae, indicating a broad-spectrum effect for this new inducer.

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Sache, Ivan, and Claude de Vallavieille-Pope. "Classification of airborne plant pathogens based on sporulation and infection characteristics." Canadian Journal of Botany 73, no. 8 (August 1, 1995): 1186–95. http://dx.doi.org/10.1139/b95-128.

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The infection cycles of 26 airborne fungal plant pathogens were compared using six monocyclic variables: latent period, infectious period, sporulation capacity, relative date of sporulation peak, lesion size, and infection efficiency. All variables were measured at the seedling stage in conditions highly conducive to disease development. Multivariate analyses of literature and experimental data were used to describe epidemic strategies based on compensation, addition, and multiplication effects between the monocyclic variables. A typology of fungi according to these effects is proposed, the main divisions of which follow the pattern of lesion growth (semisystemic, local, or negligible). Further subdivisions were obtained based on the other sporulation and infection variables. With a few exceptions, pathogens belonging to the same taxonomic (powdery mildews, downy mildews, rusts) and ecological (biotrophs, necrotrophs) group were grouped together in the proposed typology. Among rusts and necrotrophs, the fungi adapted to temperate and warm climates were also distinguished. The wheat stripe rust was not grouped with the other rusts because of unique epidemiological characteristics, especially semisystemic growth of lesions. Key words: biotrophic fungus, comparative epidemiology, monocyclic process, necrotrophic fungus.

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López-Cruz, Jaime, Óscar Crespo-Salvador, and Carmen González-Bosch. "Infection with Botrytis cinerea that lacks NADPH oxidase provides new insights into the impact of the redox environment on plant responses against this necrotroph." Free Radical Biology and Medicine 120 (May 2018): S104. http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.344.

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Raiola, Alessandro, Vincenzo Lionetti, Ibrahim Elmaghraby, Peter Immerzeel, Ewa J. Mellerowicz, Giovanni Salvi, Felice Cervone, and Daniela Bellincampi. "Pectin Methylesterase Is Induced in Arabidopsis upon Infection and Is Necessary for a Successful Colonization by Necrotrophic Pathogens." Molecular Plant-Microbe Interactions® 24, no. 4 (April 2011): 432–40. http://dx.doi.org/10.1094/mpmi-07-10-0157.

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The ability of bacterial or fungal necrotrophs to produce enzymes capable of degrading pectin is often related to a successful initiation of the infective process. Pectin is synthesized in a highly methylesterified form and is subsequently de-esterified in muro by pectin methylesterase. De-esterification makes pectin more susceptible to the degradation by pectic enzymes such as endopolygalacturonases (endoPG) and pectate lyases secreted by necrotrophic pathogens during the first stages of infection. We show that, upon infection, Pectobacterium carotovorum and Botrytis cinerea induce in Arabidopsis a rapid expression of AtPME3 that acts as a susceptibility factor and is required for the initial colonization of the host tissue.

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Anta-Fernández, Francisco, Daniela Santander-Gordón, Sioly Becerra, Rodrigo Santamaría, José María Díaz-Mínguez, and Ernesto Pérez Benito. "Nitric Oxide Metabolism Affects Germination in Botrytis cinerea and Is Connected to Nitrate Assimilation." Journal of Fungi 8, no. 7 (July 1, 2022): 699. http://dx.doi.org/10.3390/jof8070699.

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Nitric oxide regulates numerous physiological processes in species from all taxonomic groups. Here, its role in the early developmental stages of the fungal necrotroph Botrytis cinerea was investigated. Pharmacological analysis demonstrated that NO modulated germination, germ tube elongation and nuclear division rate. Experimental evidence indicates that exogenous NO exerts an immediate but transitory negative effect, slowing down germination-associated processes, and that this effect is largely dependent on the flavohemoglobin BCFHG1. The fungus exhibited a “biphasic response” to NO, being more sensitive to low and high concentrations than to intermediate levels of the NO donor. Global gene expression analysis in the wild-type and ΔBcfhg1 strains indicated a situation of strong nitrosative and oxidative stress determined by exogenous NO, which was much more intense in the mutant strain, that the cells tried to alleviate by upregulating several defense mechanisms, including the simultaneous upregulation of the genes encoding the flavohemoglobin BCFHG1, a nitronate monooxygenase (NMO) and a cyanide hydratase. Genetic evidence suggests the coordinated expression of Bcfhg1 and the NMO coding gene, both adjacent and divergently arranged, in response to NO. Nitrate assimilation genes were upregulated upon exposure to NO, and BCFHG1 appeared to be the main enzymatic system involved in the generation of the signal triggering their induction. Comparative expression analysis also showed the influence of NO on other cellular processes, such as mitochondrial respiration or primary and secondary metabolism, whose response could have been mediated by NmrA-like domain proteins.

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Agan, Ahto, Rein Drenkhan, Kalev Adamson, Leho Tedersoo, Halvor Solheim, Isabella Børja, Iryna Matsiakh, Volkmar Timmermann, Nina Elisabeth Nagy, and Ari Mikko Hietala. "The Relationship between Fungal Diversity and Invasibility of a Foliar Niche—The Case of Ash Dieback." Journal of Fungi 6, no. 3 (August 26, 2020): 150. http://dx.doi.org/10.3390/jof6030150.

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European ash (Fraxinus excelsior) is threatened by the invasive ascomycete Hymenoscyphus fraxineus originating from Asia. Ash leaf tissues serve as a route for shoot infection but also as a sporulation substrate for this pathogen. Knowledge of the leaf niche partitioning by indigenous fungi and H. fraxineus is needed to understand the fungal community receptiveness to the invasion. We subjected DNA extracted from unwashed and washed leaflets of healthy and diseased European ash to PacBio sequencing of the fungal ITS1-5.8S-ITS2 rDNA region. Leaflets from co-inhabiting rowan trees (Sorbus aucuparia) served as a reference. The overlap in leaflet mycobiomes between ash and rowan was remarkably high, but unlike in rowan, in ash leaflets the sequence read proportion, and the qPCR-based DNA amount estimates of H. fraxineus increased vigorously towards autumn, concomitant with a significant decline in overall fungal richness. The niche of ash and rowan leaves was dominated by epiphytic propagules (Vishniacozyma yeasts, the dimorphic fungus Aureobasidion pullulans and the dematiaceous hyphomycete Cladosporium ramotenellum and H. fraxineus), and endophytic thalli of biotrophs (Phyllactinia and Taphrina species), the indigenous necrotroph Venturia fraxini and H. fraxineus. Mycobiome comparison between healthy and symptomatic European ash leaflets revealed no significant differences in relative abundance of H. fraxineus, but A. pullulans was more prevalent in symptomatic trees. The impacts of host specificity, spatiotemporal niche partitioning, species carbon utilization profiles and life cycle traits are discussed to understand the ecological success of H. fraxineus in Europe. Further, the inherent limitations of different experimental approaches in the profiling of foliicolous fungi are addressed.

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Nandi, Ashis, Wolfgang Moeder, Pradeep Kachroo, Daniel F. Klessig, and Jyoti Shah. "Arabidopsis ssi2-Conferred Susceptibility to Botrytis cinerea Is Dependent on EDS5 and PAD4." Molecular Plant-Microbe Interactions® 18, no. 4 (April 2005): 363–70. http://dx.doi.org/10.1094/mpmi-18-0363.

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Loss of a stearoyl-ACP desaturase activity in the Arabidopsis thaliana ssi2 mutant confers susceptibility to the necrotroph, Botrytis cinerea. In contrast, the ssi2 mutant exhibits enhanced resistance to Pseudomonas syringae, Peronospora parasitica, and Cucumber mosaic virus. The altered basal resistance to these pathogens in the ssi2 mutant plant is accompanied by the constitutive accumulation of elevated salicylic acid (SA) level and expression of the pathogenesis-related 1 (PR1) gene, the inability of jasmonic acid (JA) to activate expression of the defensin gene, PDF1.2, and the spontaneous death of cells. Here, we show that presence of the eds5 and pad4 mutant alleles compromises the ssi2-conferred resistance to Pseudomonas syringae pv. maculicola. In contrast, resistance to B. cinerea was restored in the ssi2 eds5 and ssi2 pad4 double-mutant plants. However, resistance to B. cinerea was not accompanied by the restoration of JA responsiveness in the ssi2 eds5 and ssi2 pad4 plants. The ssi2 eds5 and ssi2 pad4 plants retain the ssi2-conferred spontaneous cell death phenotype, suggesting that cell death is not a major factor that predisposes the ssi2 mutant to infection by B. cinerea. Furthermore, the high SA content of the ssi2 pad4 plant, combined with our previous observation that the SA-deficient ssi2 nahG plant succumbs to infection by B. cinerea, suggests that elevated SA level does not have a causal role in the ssi2-conferred susceptibility to B. cinerea. Our results suggest that interaction between an SSI2-dependent factor or factors and an EDS5- and PAD4- dependent mechanism or mechanisms modulates defense to B. cinerea.

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Bhadauria, Vijai, Sabine Banniza, Albert Vandenberg, Gopalan Selvaraj, and Yangdou Wei. "Overexpression of a Novel Biotrophy-Specific Colletotrichum truncatum Effector, CtNUDIX, in Hemibiotrophic Fungal Phytopathogens Causes Incompatibility with Their Host Plants." Eukaryotic Cell 12, no. 1 (September 7, 2012): 2–11. http://dx.doi.org/10.1128/ec.00192-12.

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ABSTRACT The hemibiotrophic fungus Colletotrichum truncatum causes anthracnose disease on lentils and a few other grain legumes. It shows initial symptomless intracellular growth, where colonized host cells remain viable (biotrophy), and then switches to necrotrophic growth, killing the colonized host plant tissues. Here, we report a novel effector gene, CtNUDIX , from C. truncatum that is exclusively expressed during the late biotrophic phase (before the switch to necrotrophy) and elicits a hypersensitive response (HR)-like cell death in tobacco leaves transiently expressing the effector. CtNUDIX homologs, which contain a signal peptide and a Nudix hydrolase domain, may be unique to hemibiotrophic fungal and fungus-like plant pathogens. CtNUDIX lacking a signal peptide or a Nudix motif failed to induce cell death in tobacco. Expression of CtNUDIX:eGFP in tobacco suggested that the fusion protein might act on the host cell plasma membrane. Overexpression of CtNUDIX in C. truncatum and the rice blast pathogen, Magnaporthe oryzae , resulted in incompatibility with the hosts lentil and barley, respectively, by causing an HR-like response in infected host cells associated with the biotrophic invasive hyphae. These results suggest that C. truncatum and possibly M. oryzae elicit cell death to signal the transition from biotrophy to necrotrophy.

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Turrion-Gomez, Juan Luis, Arturo P. Eslava, and Ernesto P. Benito. "The flavohemoglobin BCFHG1 is the main NO detoxification system and confers protection against nitrosative conditions but is not a virulence factor in the fungal necrotroph Botrytis cinerea." Fungal Genetics and Biology 47, no. 5 (May 2010): 484–96. http://dx.doi.org/10.1016/j.fgb.2010.03.001.

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Fatima, Urooj, Priyadarshini Bhorali, Sudarshana Borah, and Muthappa Senthil-Kumar. "Perspectives on the utilization of resistance mechanisms from host and nonhost plants for durable protection of Brassica crops against Alternaria blight." PeerJ 7 (September 26, 2019): e7486. http://dx.doi.org/10.7717/peerj.7486.

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Background Alternaria brassicae, the causal organism of Alternaria blight, is a necrotroph infecting crops of the Brassicaceae family at all growth stages. To circumvent this problem, several disease management strategies are being used in the field, and disease-resistant varieties have also been developed. However, no strategy has proven completely successful, owing to the high variability in virulence among A. brassicae isolates, which causes a diverse spectrum of symptoms. Nonhost resistance (NHR) is a robust and broad-spectrum defense mechanism available in plants, and the exploitation of gene pools from plant species that are nonhost to A. brassicae could serve as novel sources of resistance. Methodology We searched the literature using key words relevant to this study in various search engines, such as PubMed, Web of Science, and Google Scholar, as well as certain journal websites. The literature was retrieved, sorted, and mined to extract data pertinent to the present review. Results In this review, we have comprehensively covered the recent progress made in developing Alternaria blight resistance in Brassica crops by exploiting host germplasm. We also enumerate the potential NHR sources available for A. brassicae and the NHR layers possibly operating against this pathogen. In addition, we propose different strategies for identifying NHR-related genes from nonhost plants and testing their relevance in imparting broad-spectrum resistance when transferred to host plants. Conclusion This review will help broaden the current knowledge base pertaining to the resistance sources available in host germplasm, the exploitation of NHR mechanisms, and their applications in protecting Brassica crops from Alternaria blight. The insights might also be applicable to a wider repertoire of plant pathogens.

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Mims, Charles W., Richard T. Hanlin, and Elizabeth A. Richardson. "Ultrastructure of the fungus Ophiodothella vaccinii in infected leaves of Vaccinium arboreum." Canadian Journal of Botany 84, no. 8 (August 2006): 1186–95. http://dx.doi.org/10.1139/b06-086.

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Light and electron microscopy were used to study the fungus Ophiodothella vaccinii E.S. Boyd in infected leaves of Vaccinium arboreum Marsh. This pathogen produces large lesions on leaves in which host cells are surrounded by intercellular hyphae and penetrated by intracellular hyphae. In this study, we examined details of acervuli that are produced on these lesions, the process of conidiogenesis that took place within acervuli, and the relationships between hyphae and host cells within lesions. Most acervuli developed on the adaxial leaf surface just beneath the epidermis, which also was permeated by fungal hyphae. The epidermis covering an acervulus separated from the underlying host cells as numerous conidia embedded in extracellular material accumulated within an acervulus. The raised portion of the epidermis formed a shield-like clypeus over the acervulus. Mature conidia coated with extracellular material were released through a small pore in the clypeus. A columnar mass of sterile hyphae was present in each acervulus near the pore region. This mass was surrounded by conidia embedded in extracellular material. Conidia arose from a layer of phialides present at the base of an acervulus. Phialides arose from both intercellular hyphae and intracellular hyphae that emerged from host cells and also were surrounded by extracellular material. In older lesions, O. vaccinii clearly functioned as a necrotroph. However, in young lesions, we found evidence indicating that some cells were alive when penetrated by hyphae. Hyphae were highly constricted at host cell wall penetration sites and intracellular hyphae commonly grew completely through infected host cells and directly into adjacent cells. Hyphae in older lesions became extremely thick walled and were packed with large lipid bodies.

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Bandara, Y. M. A. Y., D. K. Weerasooriya, S. Liu, and C. R. Little. "The Necrotrophic Fungus Macrophomina phaseolina Promotes Charcoal Rot Susceptibility in Grain Sorghum Through Induced Host Cell-Wall-Degrading Enzymes." Phytopathology® 108, no. 8 (August 2018): 948–56. http://dx.doi.org/10.1094/phyto-12-17-0404-r.

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Abstract:

The cell-wall-degrading enzymes (CWDE) secreted by necrotrophs are important virulence factors. Although not unequivocally demonstrated, it has been suggested that necrotrophs induce hosts to cooperate in disease development through manipulation of host CWDE. The necrotrophic fungus Macrophomina phaseolina causes charcoal rot disease in Sorghum bicolor. An RNA-seq experiment was conducted to investigate the behavior of sorghum CWDE-encoding genes after M. phaseolina inoculation. Results revealed M. phaseolina’s ability to significantly upregulate pectin methylesterase-, polygalacturonase-, cellulase-, endoglucanase-, and glycosyl hydrolase-encoding genes in a charcoal rot-susceptible sorghum genotype (Tx7000) but not in a resistant genotype (SC599). For functional validation, crude enzyme mixtures were extracted from M. phaseolina- and mock-inoculated charcoal-rot-resistant (SC599 and SC35) and -susceptible (Tx7000 and BTx3042) sorghum genotype stalks. A gel diffusion assay (pectin substrate) revealed significantly increased pectin methylesterase activity in M. phaseolina-inoculated Tx7000 and BTx3042. Polygalacturonase activity was determined using a ruthenium red absorbance assay (535 nm). Significantly increased polygalacturonase activity was observed in two susceptible genotypes after M. phaseolina inoculation. The activity of cellulose-degrading enzymes was determined using a 2-cyanoacetamide fluorimetric assay (excitation and emission maxima at 331 and 383 nm, respectively). The assay revealed significantly increased cellulose-degrading enzyme activity in M. phaseolina-inoculated Tx7000 and BTx3042. These findings revealed M. phaseolina’s ability to promote charcoal rot susceptibility in grain sorghum through induced host CWDE.

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Andrew, Marion, Reeta Barua, Steven M. Short, and Linda M. Kohn. "Evidence for a Common Toolbox Based on Necrotrophy in a Fungal Lineage Spanning Necrotrophs, Biotrophs, Endophytes, Host Generalists and Specialists." PLoS ONE 7, no. 1 (January 11, 2012): e29943. http://dx.doi.org/10.1371/journal.pone.0029943.

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Journal articles on the topic 'Necrotroph'

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