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Literatura académica sobre el tema "Biology, Molecular|Biology, Microbiology|Agriculture, Plant Pathology"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 17 de febrero de 2022

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Artículos de revistas sobre el tema "Biology, Molecular|Biology, Microbiology|Agriculture, Plant Pathology"

Harborne, Jeffrey B. "Plant Pathology in Agriculture:". Phytochemistry 30, n.º 4 (1991): 1355. http://dx.doi.org/10.1016/s0031-9422(00)95241-5.

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Kaufmane, Edīte, Māra Skrīvele, Edgars Rubauskis, Sarmīte Strautiņa, Laila Ikase, Gunārs Lācis, Dalija Segliņa, Inga Moročko-Bičevska, Silvija Ruisa y Ilze Priekule. "Development of Fruit Science in Latvia". Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences 67, n.º 2 (1 de agosto de 2013): 71–83. http://dx.doi.org/10.2478/prolas-2013-0013.

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Development of fruit growing and fruit science in Latvia has always been closely linked to the development of the whole country. After the founding of the independent Latvia state in 1918, fruit growing developed rapidly. Although in the Soviet times the situation was not favourable for quality fruit growing, research and breeding continued with good results. After Latvia regained independence, private land property rights were restored, and interest in intensive orchard establishment and growing technologies increased rapidly, which demanded change in the research focus. At present, the Latvia State Institute of Fruit-Growing is the leading institution in this field, working in cooperation with Pūre Horticultural Research Centre, Latvian Plant Protection Research Centre, Institute of Agrobiotechology, and Faculty of Food Technology, Latvia University of Agriculture, Laboratory of Plant Mineral Nutrition, Institute of Biology, University of Latvia. Research is carried out in the following directions: breeding and cultivar evaluation; genetics and molecular biology; plant pathology and entomology; orchard management; experimental processing and storage.

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Derevnina, Lida, Benjamin Petre, Ronny Kellner, Yasin F. Dagdas, Mohammad Nasif Sarowar, Artemis Giannakopoulou, Juan Carlos De la Concepcion et al. "Emerging oomycete threats to plants and animals". Philosophical Transactions of the Royal Society B: Biological Sciences 371, n.º 1709 (5 de diciembre de 2016): 20150459. http://dx.doi.org/10.1098/rstb.2015.0459.

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Oomycetes, or water moulds, are fungal-like organisms phylogenetically related to algae. They cause devastating diseases in both plants and animals. Here, we describe seven oomycete species that are emerging or re-emerging threats to agriculture, horticulture, aquaculture and natural ecosystems. They include the plant pathogens Phytophthora infestans , Phytophthora palmivora , Phytophthora ramorum , Plasmopara obducens , and the animal pathogens Aphanomyces invadans , Saprolegnia parasitica and Halioticida noduliformans . For each species, we describe its pathology, importance and impact, discuss why it is an emerging threat and briefly review current research activities. This article is part of the themed issue ‘Tackling emerging fungal threats to animal health, food security and ecosystem resilience’.

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Wege, Sarah-Maria, Katharina Gejer, Fabienne Becker, Michael Bölker, Johannes Freitag y Björn Sandrock. "Versatile CRISPR/Cas9 Systems for Genome Editing in Ustilago maydis". Journal of Fungi 7, n.º 2 (18 de febrero de 2021): 149. http://dx.doi.org/10.3390/jof7020149.

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The phytopathogenic smut fungus Ustilago maydis is a versatile model organism to study plant pathology, fungal genetics, and molecular cell biology. Here, we report several strategies to manipulate the genome of U. maydis by the CRISPR/Cas9 technology. These include targeted gene deletion via homologous recombination of short double-stranded oligonucleotides, introduction of point mutations, heterologous complementation at the genomic locus, and endogenous N-terminal tagging with the fluorescent protein mCherry. All applications are independent of a permanent selectable marker and only require transient expression of the endonuclease Cas9hf and sgRNA. The techniques presented here are likely to accelerate research in the U. maydis community but can also act as a template for genome editing in other important fungi.

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Saad, Mohd Faiz Mat, Aziz Ramlee Sau, Muhamad Afiq Akbar, Syarul Nataqain Baharum, Ahmad Bazli Ramzi, Noraini Talip y Hamidun Bunawan. "Construction of Infectious Clones of Begomoviruses: Strategies, Techniques and Applications". Biology 10, n.º 7 (29 de junio de 2021): 604. http://dx.doi.org/10.3390/biology10070604.

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Begomovirus has become a potential threat to the agriculture sector. It causes significant losses to several economically important crops. Given this considerable loss, the development of tools to study viral genomes and function is needed. Infectious clones approaches and applications have allowed the direct exploitation of virus genomes. Infectious clones of DNA viruses are the critical instrument for functional characterization of the notable and newly discovered virus. Understanding of structure and composition of viruses has contributed to the evolution of molecular plant pathology. Therefore, this review provides extensive guidelines on the strategy to construct infectious clones of Begomovirus. Also, this technique’s impacts and benefits in controlling and understanding the Begomovirus infection will be discussed.

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Yarden, O., D. J. Ebbole, S. Freeman, R. J. Rodriguez y M. B. Dickman. "Fungal Biology and Agriculture: Revisiting the Field". Molecular Plant-Microbe Interactions® 16, n.º 10 (octubre de 2003): 859–66. http://dx.doi.org/10.1094/mpmi.2003.16.10.859.

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Plant pathology has made significant progress over the years, a process that involved overcoming a variety of conceptual and technological hurdles. Descriptive mycology and the advent of chemical plant-disease management have been followed by biochemical and physiological studies of fungi and their hosts. The later establishment of biochemical genetics along with the introduction of DNA-mediated transformation have set the stage for dissection of gene function and advances in our understanding of fungal cell biology and plant-fungus interactions. Currently, with the advent of high-throughput technologies, we have the capacity to acquire vast data sets that have direct relevance to the numerous subdisciplines within fungal biology and pathology. These data provide unique opportunities for basic research and for engineering solutions to important agricultural problems. However, we also are faced with the challenge of data organization and mining to analyze the relationships between fungal and plant genomes and to elucidate the physiological function of pertinent DNA sequences. We present our perspective of fungal biology and agriculture, including administrative and political challenges to plant protection research.

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Yadagiri, Kirthi Kiran, Julia Kerrigan y S. Bruce Martin. "Improved methods for axenic culture of Labyrinthula terrestris, causal agent of rapid blight of turfgrasses". Canadian Journal of Microbiology 58, n.º 10 (octubre de 2012): 1230–35. http://dx.doi.org/10.1139/w2012-096.

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The genus Labyrinthula is a group of unicellular microorganisms with spindle-shaped cells that move in an ectoplasmic network. Most Labyrinthula species are saprotrophic and found in coastal marine or estuarine habitats; however, exceptions exist, such as Labyrinthula terrestris , a terrestrial plant pathogen that causes rapid blight on cool-season turfgrasses. Labyrinthula spp. can be grown in culture, which facilitates studies on their biology and pathology. However, axenic culture of L. terrestris has always been challenging. We modified the most commonly used Labyrinthula growth medium, serum seawater agar (SSA), and designed 2 media for improved pure culture, modified SSA (MSSA) and grass extract SSA (GESSA). A comparative assessment of these 2 media and basic SSA was made to measure the growth responses of 18 L. terrestris isolates. Results indicate that the average colony area was greatest on GESSA followed by MSSA, while cultures lived longest on MSSA followed by GESSA. We also suggest an improved long-term culture technique to maintain viable L. terrestris isolates for at least 2 years.

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Sibiya, Malusi y Mbuyu Sumbwanyambe. "Automatic Fuzzy Logic-Based Maize Common Rust Disease Severity Predictions with Thresholding and Deep Learning". Pathogens 10, n.º 2 (28 de enero de 2021): 131. http://dx.doi.org/10.3390/pathogens10020131.

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Many applications of plant pathology had been enabled by the evolution of artificial intelligence (AI). For instance, many researchers had used pre-trained convolutional neural networks (CNNs) such as the VGG-16, Inception, and Google Net to mention a few, for the classifications of plant diseases. The trend of using AI for plant disease classification has grown to such an extent that some researchers were able to use artificial intelligence to also detect their severities. The purpose of this study is to introduce a novel approach that is reliable in predicting severities of the maize common rust disease by CNN deep learning models. This was achieved by applying threshold-segmentation on images of diseased maize leaves (Common Rust disease) to extract the percentage of the diseased leaf area which was then used to derive fuzzy decision rules for the assignment of Common Rust images to their severity classes. The four severity classes were then used to train a VGG-16 network in order to automatically classify the test images of the Common Rust disease according to their classes of severity. Trained with images developed by using this proposed approach, the VGG-16 network achieved a validation accuracy of 95.63% and a testing accuracy of 89% when tested on images of the Common Rust disease among four classes of disease severity named Early stage, Middle stage, Late Stage and Healthy stage.

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Turner, R. Steven. "Potato Agriculture, Late Blight Science, and the Molecularization of Plant Pathology". Historical Studies in the Natural Sciences 38, n.º 2 (2008): 223–57. http://dx.doi.org/10.1525/hsns.2008.38.2.223.

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By the mid-1980s nucleic-acid based methods were penetrating the farthest reaches of biological science, triggering rivalries among practitioners, altering relationships among subfields, and transforming the research front. This article delivers a "bottom up" analysis of that transformation at work in one important area of biological science, plant pathology, by tracing the "molecularization" of efforts to understand and control one notorious plant disease——the late blight of potatoes. It mobilizes the research literature of late blight science as a tool through which to trace the changing typography of the research front from 1983 to 2003. During these years molecularization intensified the traditional fragmentation of the late blight research community, even as it dramatically integrated study of the causal organism into broader areas of biology. In these decades the pathogen responsible for late blight, the oomycete Phytophthora infestans, was discovered to be undergoing massive, frightening, and still largely unexplained genetic diversification——a circumstance that lends the episode examined here an urgency that reinforces its historiographical significance as a casestudy in the molecularization of the biological sciences.

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Lee, Joan. "Reviewer Acknowledgements for Journal of Plant Studies, Vol. 7, No. 1". Journal of Plant Studies 7, n.º 1 (27 de febrero de 2018): 73. http://dx.doi.org/10.5539/jps.v7n1p73.

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Journal of Plant Studies wishes to acknowledge the following individuals for their assistance with peer review of manuscripts for this issue. Their help and contributions in maintaining the quality of the journal are greatly appreciated.Journal of Plant Studies is recruiting reviewers for the journal. If you are interested in becoming a reviewer, we welcome you to join us. Please find the application form and details at http://www.ccsenet.org/reviewer and e-mail the completed application form to jps@ccsenet.org.Reviewers for Volume 7, Number 1Adriana F. Sestras, University of Agricultural Sciences and Veterinary Medicine, RomaniaAlireza Valdiani, University of Copenhagen, DenmarkAmi Lokhandwala, University of Mississippi, Department of Biology, USAIsabel Desgagné-Penix, Université du Québec à Trois-Rivières, CanadaKirandeep Kaur Mani, California seed and Plant Labs, Pleasant Grove, CA, USAMartina Pollastrini, University of Florence, ItalyMassimo Zacchini, Institute of Agroenvironmental and Forest Biology, ItalyMatteo Busconi, Università Cattolica del Sacro Cuore, ItalyMelekber Sulusoglu, Arslanbey Vocational School Kocaeli University, TurkeyMilana Trifunovic-Momcilov, Institute for Biological Research “Sinisa Stankovic”, SerbiaMohamed Trigui, Sfax Preparatory Engineering Institute and CBS, TunisiaMohammad Nurul Amin, Noakhali Science and Technology University, BangladeshMontaser Fawzy Abdel-Monaim, Plant Pathology Res. Instatute, Agric. Res. Center, EgyptNina Ivanovska, Institute of Microbiology, BulgariaPanagiotis Madesis, Centre for Research and Technology Hellas/Institiute of Applied Biosciences, GreeceRajiv Ranjan, T. P. Varma College, IndiaRaksha Singh, University of Arkansas, USASlawomir Borek, Adam Mickiewicz University, PolandSuheb Mohammed, University of Virginia, USA

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Tesis sobre el tema "Biology, Molecular|Biology, Microbiology|Agriculture, Plant Pathology"

Ong, Laura E. "Conservation of pathogen recognition mechanisms in different plant species". [Bloomington, Ind.] : Indiana University, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3215189.

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Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2006.
Source: Dissertation Abstracts International, Volume: 67-04, Section: B, page: 1764. Adviser: Roger W. Innes. "Title from dissertation home page (viewed June 20, 2007)."

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Idris, Ali Mohamed 1958. "Biological and molecular differentiation of subgroup III geminiviruses". Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282381.

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The biological and molecular properties of Sinaloa tomato leaf curl virus (STLCV) were investigated to test the hypothesis that STLCV is a previously uncharacterized whitefly-transmitted geminivirus from North America. STLCV causes leaf curling and yellowing in tomato plants. STLCV was transmissible to N. benthamiana by sap inoculation, and to Solanaceous and Malvaceous species by the whitefly vector. STLCV has transmission characteristics like other persistent viruses, and was not transovarially passaged. PCR fragments containing the large intergenic region (IR) of the STLCV A and B components and coat protein gene (AR1) were cloned from STLCV-infected tomato, and their DNA sequences obtained. Regions 174 nt in length containing diagnostic sequences present in the IR of geminiviruses, and a putative ORF AR1 of 756 nt were identified. A and B component IR sequences were 97.9% identical, suggesting a homogeneous, bipartite viral quasi-species. Pairwise alignment (Wilbur-Lipman) of STLCV AR1 and those of subgroups I, II, and III geminiviruses indicated 22-81% similarity, whereas STLCV AR1 was 36-61% similar to subgroup III viruses, collectively, suggesting STLCV is a unique viral quasi-species (>90% = same virus). Multiple sequence alignment (Clustal) and parsimony analysis (PAUP) of IR or AR1 sequences supported placement of STLCV with Western Hemisphere subgroup III viruses. Both A and B types of the whitefly vector transmitted tomato yellow leaf curl (TYLCV-Th) and chino del tomate (CdTV) geminiviruses, and transmission frequencies increased with greater AAPs. TYLCV-Th was transmitted by both vectors at a higher frequency than was CdTV. The B type, indigenous to the Eastern Hemisphere, transmitted the Old World TYLCV-Th (87%) more effectively than the New World A type vector (63%). The Western Hemisphere CdTV, was transmitted more often by the A type whitefly (50%), also from the New World, than by B type (27%). PCR detection of geminiviruses in single whiteflies indicated virus ingestion occurred after a 0.5 h AAP. Detection frequencies increased in both whiteflies given longer AAPs (0.5-72 h), irrespective of virus tested. PCR primers were designed that effectively discriminate between Old and New World geminiviruses, and between monopartite and bipartite genomic organizations.

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Acosta-Leal, Rodolfo. "A plant resistance mechanism that promotes the emergence of resistance-breaking variants of potato Y potyvirus". Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/288987.

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Tobacco Virgin A Mutant (VAM) exhibits apparent immunity to several potyviruses in a strain-specific manner. Its resistance was generated by UV irradiation, and is partially conditioned by the recessive gene va. This allele has been introgressed into several breeding fines such as NC745. Previously, it was observed that the inoculation of an avirulent strain of potato Y potyvirus (PVY(NN)) in both resistant genotypes, caused systemic infection in some NC745 plants only, and the virus recovered from these plants acquired an ability to easily infect both NC745 and VAM. The current study was to identify the host factors that define each one of these resistant phenotypes, and to characterize the pathogenic properties of the evolving virus. VAM cells supported a reduced rate of PVY(NN)-accumulation compared with NC745 cells, which accumulated virus progeny at, he same level as the susceptible control Burley 21 (B21). However, in both resistant tobaccos the virus cell-to-cell movement was similarly impaired. Even so, PVY(NN) was recovered sooner from NC745- than from VAM-inoculated leaves. After PVY(NN)-detection, emerging resistance breaking (RB) variants were also recovered. Surprisingly, just in VAM, the RB variants never moved out of the inoculated leaves, until they were reinoculated in the same or another uninoculated VAM plant. The inability of the emerging RB variants to exit the PVY(NN)-inoculated VAM leaves was associated with their low accumulation rate and an obstruction imposed by coinfecting avirulent genotypes. The VAM factor restricting virus accumulation was inherited independently from va and operated in an allele doses manner. This gene, named rvam2, was easily overcome by the isolated RB variants, but the underlying virus modification(s) implied a loss of fitness in B21. Thus, the systemic emergence of RB variants, starting from a quasispecies, adapted to accumulate in Rvam2 genotypes (e.g., B21), seems to require a high rate of local virus accumulation linked to a selective constraint in the virus intercellular and/or intertissular traffic. This is the first report where the combined action of two vulnerable resistance mechanisms confers a stronger plant resistance to a viral systemic infection.

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Chancey, Scott Thomas. "Regulation of the production of phenazine antibiotics by the GacS/GacA two-component system in Pseudomonas aureofaciens 30-84". Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279779.

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Pseudomonas aureofaciens 30-84, a biological control bacterium for the soil-borne disease take-all of wheat, is a model system for biological control of root-infecting fungal pathogens. Strain 30-84 inhibits the causal agent of take-all, Gaeumannomyces graminis var. tritici, primarily through the production of phenazine antibiotics, which are important for survival of the bacterium in the rhizosphere. Prior to this work, phenazine production was shown to be regulated by an N-acyl-homoserine lactone (AHL) response system encoded by phzI and phzR. This work identified a second regulatory system involved in the phenazine regulatory cascade. The two-component regulatory system involving the GacS/GacA proteins regulates the production of phenazines, extracellular protease, hydrogen cyanide and fluorescent siderophores. GacS/GacA regulates the production of phenazines at multiple levels. They control the production of the AHL signal required for expression of the phenazine biosynthetic operon by tightly regulating transcription of phzI. This was the first report of a linkage between a two-component regulatory system and an AHL response system. GacS/GacA also control phenazine production through a second mechanism. Preliminary evidence suggests translational regulation of one or more genes involved in the phenazine regulatory cascade through transcriptional control of a regulatory RNA (rsmB RNA) required to neutralize the negative effects of the translational repressor RsmA. Another aspect of this work was the analysis of the formation and rhizosphere competence of spontaneous gacS and gacA mutants of strain 30-84. These are commonly isolated from laboratory cultures of all biocontrol bacteria and could pose a threat to the efficacy of biological control if they arise in the rhizosphere and displace the phenazine-producing wild type strain 30-84. This work indicated that the mutants did arise on wheat roots and did displace strain 30-84 on roots in sterile soil. However, the mutants did not displace strain 30-84 on roots in natural soil. In fact, the wild type strain 30-84 appeared to compete more favorably with indigenous microorganisms in the presence of a subpopulation of GacS/GacA mutants. Therefore, the results presented here indicate that a subpopulation of gacS and gacA mutants is a normal and beneficial part of the P. aureofaciens community in the rhizosphere.

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Rudnick, Paul Anthony. "Studies on the regulatory mechanisms controlling nitrogenase synthesis and ammonia assimilation in Azotobacter vinelandiiand Sinorhizobium meliloti". Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279942.

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Biological nitrogen fixation (BNF) is the nitrogenase-catalyzed conversion of dinitrogen to ammonia by a select group of Bacteria and Archaea called diazotrophs. In turn, plants and other microbes assimilate ammonia during the synthesis of nucleic acids, proteins and other biomolecules. BNF is of special interest in agriculture where it replenishes soil nitrogen lost during repetitive farming. Basic knowledge of BNF might eventually lead to less dependence on expensive and polluting chemical fertilizers. For the studies presented here, two model diazotrophs, the free-living Azotobacter vinelandii , and the alfafa symbiont, Sinorhizobium meliloti, were used to investigate mechanisms controlling nitrogen fixation and nitrogen metabolism. In A. vinelandii, ammonia inhibits nitrogenase expression by limiting activity of the two-component activator, NifA; this involves the negatively acting sensor protein, NifL. Groundwork indicated that a global nitrogen-sensing system, present in many bacteria might control NifA activity since glnD mutants were unable to fix nitrogen. In other organisms, nitrogen limitation signals GlnD-mediated uridylylation of PII-like signal transduction proteins, which signals activation of a suite of genes involved in nitrogen source utilization. The goals of the current study were to characterize the operon encoding a PII-like protein in A. vinelandii, named GlnK, and determine its influence on NifA and nitrogen metabolism. The results indicated that glnK is an essential gene and that uridylylation of GlnK is required for activation of glutamine synthetase and NifA. Also presented here is evidence that GlnK interacts with NifL to stimulate its inhibitory properties. These results are consistent with a model in which uridylylation of GlnK in response to nitrogen limitation signals relief of NifL inhibition. In the last section of this dissertation, glnD of Sinorhizobium meliloti was cloned and sequenced because a PII-like protein had been previously implicated in control of nodule development and symbiosis. Unfortunately, S. meliloti glnD mutants could not be isolated unless glnD and flanking genes were provided in trans, indicating that the glnD operon is indispensable. These studies provide new insight into the global mechanisms controlling nitrogen fixation and metabolism and suggest that GlnD and PII-like proteins may regulate other targets, some of which are essential.

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Wood, Derek William 1965. "Characterization of an N-acyl-L-homoserine lactone-mediated regulatory system controlling phenazine biosynthesis in Pseudomonas aureofaciens 30-84: In vitro and in situ analysis". Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282391.

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Pseudomonas aureofaciens 30-84 is a soilborne bacterium that colonizes the wheat rhizosphere. This strain produces three phenazine antibiotics which are responsible for both suppression of take-all disease of wheat caused by Gaeumannomyces graminis var. tritici and enhanced survival of 30-84 within the wheat rhizosphere in competition with other organisms. A gene (phzR) was identified just prior to the start of this work that is required for phenazine production by 30-84. PhzR was identified as a positive regulator of the phenazine biosynthetic operon. During the course of this dissertation it was discovered that PhzR belongs to the LuxR family of N-acyl- scL-homoserine lactone-responsive transcriptional regulators and that phenazine production in P. aureofaciens 30-84 is mediated by a diffusible signal molecule. The gene responsible for production of this signal (phzI) was identified. Both phzI and phzR are required for the production of phenazines in vitro. Together these two proteins (PhzR/PhzI) comprise a N-acyl- scL-homoserine lactone (AHL) response system that controls phenazine antibiotic production in P. aureofaciens 30-84. Classic AHL-mediated regulatory systems consist of two proteins, a LuxR homolog (PhzR) which transcriptionally activates target gene expression in response to AHL produced by the second protein, the LuxI homolog (PhzI). Using HPLC coupled with high resolution mass spectroscopy, the specific AHL produced via PhzI has been identified as N-hexanoyl- scL-homoserine lactone (HHL). It has been determined that PhzR activates phenazine production in conjunction with HHL produced by PhzI via transcriptional activation of the phenazine biosynthetic gene phzB. A variety of synthetic AHLs restore transcription of phzB and phenazine production in phzI mutants suggesting that phzI mutants can be used to detect the presence of exogenous AHLs. This ability was exploited to show that HHL is required for phenazine expression in situ and is an effective interpopulation signal molecule in the wheat rhizosphere. The work presented in this dissertation is the first to show that AHL-mediated regulation, previously only examined in vitro, can operate within the natural habitat of a bacterium.

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Lee, Sunhee y Sunhee Lee. "Characterization of a major cluster of genes involved in nitrogen fixation and another required for indole-3-acetic acid biosynthesis in the sugarcane endophyte, Acetobacter diazotrophicus". Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279953.

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Acetobacter diazotrophicus is a true endophyte of sugarcane and is often found in plants grown in agricultural areas of low nitrogen fertilizer input. Results from our laboratory, using mutant strains of A. diazotrophicus unable to fix nitrogen, have shown that there are two beneficial effects of A. diazotrophicus on sugarcane: one dependent on nitrogen fixation, and the other independent of nitrogen fixation. A plant growth promoting substance like indole-3-acetic acid (IAA) may represent the latter effect that accounts for improved plant growth. My first project was to characterize the genes responsible for nitrogen fixation, and determine their regulation. In summary, I have isolated, sequenced, and analyzed the major 31.5 kb nif gene cluster, including both nif and associated genes of A. diazotrophicus. This cluster of 33 genes represents the largest and most complete assembly of contiguous nif/fix and associated genes characterized in any diazotrophic bacterial species. My second project has been to determine whether nitrogen fixation and/or IAA production are important for the ability of A. diazotrophicus to stimulate plant growth. In order to determine the role of IAA directly, mutants of A. diazotrophicus producing reduced amounts of IAA were generated by Tn5 mutagenesis. Among IAA - candidates, one excreting less than 6% of IAA compared to the parent strain was further characterized. The mutation was mapped to genes involved in cytochrome c biogenesis (ccm genes-c&barbelow;ytochrome c&barbelow; m&barbelow;aturation genes). A Nif -/Iaa- double mutant and Nif- mutant were constructed by inserting a chloramphenicol cassette into nifD region. Plant inoculation experiments using mutant strains also demonstrated that A. diazotrophicus could stimulate plant growth regardless of N availability, as evidenced by the significant growth difference between plants inoculated with wild type and uninoculated plants. Under N-limiting conditions plants inoculated with wild type had greater height and biomass than plants inoculated with Nif- or Nif -/Iaa- mutants, suggesting nitrogen fixation by A. diazotrophicus stimulates sugarcane growth. Plants inoculated with Iaa- mutants were always comparable to uninoculated plants regardless of N availability, indicating that IAA biosynthesis is a major bacterial factor influencing sugarcane growth, particularly under N-sufficient conditions.

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Morello, Joanne. "Characterization of negative signaling between wheat rhizosphere bacteria and the biological control agent Pseudomonas aureofaciens strain 30-84". Thesis, The University of Arizona, 2002. http://hdl.handle.net/10150/278800.

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The biological control bacterium Pseudomonas aureofaciens strain 30-84 produces three phenazine antibiotics. Phenazines are responsible for pathogen inhibition by strain 30-84 as well as its ability to persist in the rhizosphere. Although this bacterium can suppress take-all of wheat disease when applied as a seed inoculum, performance of this agent, as with many biological control agents, can be variable in the field. A factor in establishment and pathogen inhibition may be the indigenous microbial community that competes with strain 30-84 and may interfere with phenazine production as a competitive mechanism. In this study, a wheat rhizosphere microbial community library was screened and ca. 4% of the isolates were found to inhibit phenazine production by strain 30-84. A sub-group of these isolates was characterized and found to produce extracellular signals that suppressed phenazine gene expression. The signal from isolate PU-15 was initially characterized and appeared to be chemically and mechanistically unlike other known negative-acting signals. A genetic region was cloned from this isolate that decreased phenazine gene expression and production in strain 30-84. Negative communication also affected the ability of strain 30-84 to inhibit the pathogenic fungus Gaeuman-nomyces graminis pv. tritici in vitro. Therefore, negative communication may contribute to the inconsistencies of biological control in the field.

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Doan, Hung Kim. "Seed Treatments and Detection of Fusarium oxysporum f. sp. vasinfectum race 4". Thesis, University of California, Davis, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1565656.

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Fusarium wilt of cotton, caused by the soilborne fungus Fusarium oxysporum f. sp. vasinfectum, is a widespread disease occurring in most cotton-growing regions of the world. Fusarium wilt occurs in all domesticated cotton. Currently, six nominal races are recognized: 1, 2, 3, 4, 6, and 8, as well as many un-named genotypes worldwide. Many are widespread in the U.S., but race 4, which is highly virulent, is apparently restricted to California. Race 4 is found in an increasing number of fields in California due in part to seed-borne dissemination. The first aim of this study was to evaluate the efficacy of hot water treatments alone or in conjunction with fungicides and other treatments to reduce the viability of FOV race 4 in infected cotton seed. The second aim was to develop and evaluate a rapid and reliable molecular diagnostic assay, the AmplifyRP^® Acceler8™, for the direct detection of FOV race 4 in cotton tissue. In the seed treatment assay, a 1 hour immersion of seed in water or sterile 30% potato dextrose broth (PDB) at 24°C followed by a 20 minute immersion in a 60°C solution containing four fungicides (azoxystrobin, fludioxonil, thiabendazole, and thiophanate) or thiophanate alone were the most effective pretreatment-treatment combinations in reducing FOV in seed and avoiding loss of seed germination and vigor. The incidence of FOV in the seed was reduced by approximately 86% without reducing seed germination and vigor based on recovery of the fungus on petri plates and greenhouse grow-out assays. FOV was completely eliminated from infected seed when the seed was pretreated in water at 24°C followed by a 20 minute immersion in a solution of thiophanate heated to 70°C. With this treatment, seed germination was reduced by 36% and vigor was reduced by 38%. The AmplifyRP^® Acceler8™ diagnostic assay consistently detected FOV race 4 from all infected tissue samples. The test is rapid, simple and more sensitive than conventional PCR. The AmplifyRP^® Acceler8™ diagnostic assay detected DNA from FOV race 4 at concentrations of 1 ng/µL and above. In addition, it did not amplify DNA from other known FOV races (races 1, 2, 3, 6, and 8). The whole process from sample preparation to reading the results was completed in as little as 30 minutes. The test detected FOV race 4 in cotton taproots, petioles, and stems.

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Langham, Richard James. "Molecular characterization of the saguaro cactus virus RNA-dependent RNA polymerase and capsid protein". Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284098.

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Saguaro cactus virus (SCV) is a single-stranded RNA virus which belongs to the carmovirus genus within the family Tombusviridae. A full-length infectious clone of SCV has been generated and in this study was used to: (1) elucidate the role of the capsid protein (CP) in cell-to-cell and long distance movement, and (2) to better understand the various function(s) of the p26 and p86 proteins in viral replication. Analysis of a series of frameshift mutants and a deletion mutant has demonstrated that the CP is required for cell-to-cell movement in both Chenopodium amaranticolor and C. capitatum. This analysis also revealed a requirement of the CP coding region for viral replication in protoplasts. This is the first report of a cis-element, required for tombusvirus replication, which extends beyond the 3'-untranslated region into the CP coding region. The p26 and p86 constitute the putative SCV RNA-dependent RNA polymerase (RdRp). To better understand the structure and function of the RdRp, 16 clustered charged-to-alanine mutants were generated in the p26 and p86. The infectivity as well as the ability of each of these mutants to replicate in protoplasts was analyzed and compared to the infectivity and replication level of the wild type (pSCV15). Of the 16 mutants, five of them were nearly as infectious as wild type and were also able to replicate at near wild type levels. Four of the mutants consistently displayed a lower replication rate as determined by Northern analysis with two of these four demonstrating a lower level of infectivity on indicator plants. Two other mutants demonstrated a level of replication which was only able to be detected by RT-PCR. These mutants were not able to elicit the formation of local lesions on C. amaranticolor or induce symptoms on either inoculated or systemic leaves of C. capitatum. The ability of these mutants to synthesize negative-strand RNA, was examined. It was determined that all of the mutants which were able to produce positive-strand RNA were also able to synthesize negative strand RNA as determined by RT-PCR. Five of the mutants were not able to replicate in protoplasts and were not infectious on either host. These remaining five uninfectious mutants were also unable to replicate either negative or positive-strand RNA.

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Libros sobre el tema "Biology, Molecular|Biology, Microbiology|Agriculture, Plant Pathology"

J, Gurr S., McPherson M. J y Bowles D. J, eds. Molecular plant pathology. Oxford: IRL Press at Oxford University Press, 1992.

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S, Gurr, ed. Molecular Plant Pathology: Practical Approach. I.R.L. P., 1992.

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Jane, Gurr Sarah, McPherson M. J y Bowles Dianna J, eds. Molecular plant pathology: A practical approach. Oxford: IRC Press at Oxford University Press, 1992.

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(Editor), S. J. Gurr, M. J. McPherson (Editor) y D. J. Bowles (Editor), eds. Molecular Plant Pathology: A Practical Approach Volume I (Practical Approach Series). Oxford University Press, USA, 1992.

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(Editor), S. J. Gurr, M. J. McPherson (Editor) y D. J. Bowles (Editor), eds. Molecular Plant Pathology: A Practical Approach Volume I (The Practical Approach). Oxford University Press, USA, 1992.

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(Editor), S. J. Gurr, M. J. McPherson (Editor) y D. J. Bowles (Editor), eds. Molecular Plant Pathology: A Practical Approach Volume II (Practical Approach Series). Oxford University Press, USA, 1992.

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(Editor), S. J. Gurr, M. J. McPherson (Editor) y D. J. Bowles (Editor), eds. Molecular Plant Pathology: A Practical Approach Volume II (The Practical Approach Series). Oxford University Press, USA, 1992.

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(Editor), S. J. Gurr, M. J. McPherson (Editor) y D. J. Bowles (Editor), eds. Molecular Plant Pathology: A Practical Approach Volumes I and II as a set (The Practical Approach Series). Oxford University Press, USA, 1993.

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Stirling, Graham, Helen Hayden, Tony Pattison y Marcelle Stirling. Soil Health, Soil Biology, Soilborne Diseases and Sustainable Agriculture. CSIRO Publishing, 2016. http://dx.doi.org/10.1071/9781486303052.

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Our capacity to maintain world food production depends heavily on the thin layer of soil covering the Earth's surface. The health of this soil determines whether crops can grow successfully, whether a farm business is profitable and whether an enterprise is sustainable in the long term. Farmers are generally aware of the physical and chemical factors that limit the productivity of their soils but often do not recognise that soil microbes and the soil fauna play a major role in achieving healthy soils and healthy crops. Soil Health, Soil Biology, Soilborne Diseases and Sustainable Agriculture provides readily understandable information about the bacteria, fungi, nematodes and other soil organisms that not only harm food crops but also help them take up water and nutrients and protect them from root diseases. Complete with illustrations and practical case studies, it provides growers and their consultants with holistic solutions for building an active and diverse soil biological community capable of improving soil structure, enhancing plant nutrient uptake and suppressing root pests and pathogens. The book is written by scientists with many years' experience developing sustainable crop production practices in the grains, vegetable, sugarcane, grazing and horticultural industries. This book will be useful for: growers, consultants, agronomists and soil chemists, extension personnel working in the grains, livestock, sugarcane and horticultural industries, professionals running courses in soil health/biological farming, and students taking university courses in soil science, ecology, microbiology, plant pathology and other biological sciences.

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