Journal articles: 'Gametangia'

1

Nour-El-Deen, Samar. "Anomalous gametangia inFissidensfrom Egypt." Journal of Bryology 33, no. 3 (September 2011): 252–54. http://dx.doi.org/10.1179/1743282011y.0000000019.

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Pujos, José. "Systèmes de croisement et fécondité chez le Sphagnum." Canadian Journal of Botany 72, no. 10 (October 1, 1994): 1528–34. http://dx.doi.org/10.1139/b94-188.

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Sexuality is most often preserved in Sphagnum while asexual reproduction remains responsible for the perennity and multiplication of the species. Sexual reproduction success was assessed for two diecious species and four monecious – polyecious species, using fertilization rates, reproduction rates, and success of the reproduction. The effects of different crossing processes on the preceding parameters were emphasized. Accordingly, gynoecium numbers, archegone numbers per gynoecium, and sporogonia occurrences were assessed in more than 3500 capitula. Variable distribution of gametangia within capitula in different species determines the success of sexual reproduction. An evolutionary interpretation of this variation in the distribution of gametangia is proposed. Key words: Sphagnum, crossing processes, polyecious, sexualization rates, reproduction success. [Journal translation]

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3

Brasier, Clive, and Susan Kirk. "Production of gametangia by Phytophthora ramorum in vitro." Mycological Research 108, no. 7 (July 2004): 823–27. http://dx.doi.org/10.1017/s0953756204000565.

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Phillips, JA. "Taxonomy and reproduction in Australian species of Diliphus (Dictyotales, Phaeophyta)." Australian Systematic Botany 5, no. 6 (1992): 657. http://dx.doi.org/10.1071/sb9920657.

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Eight species of Dilophus are recognised for Australia. Detailed descriptions are given for five species, D. fastigiatus, D. gunnianus, D. intermedius, D. marginatus and D. robustus. D. moniliformis and D. crinitus from Western Australia and D. decumbens from subantarctic Macquarie I. remain poorly known. Sporophytes and gametophytes are reported for the five species providing first records of sporophytes of D. robustus, female gametophytes of D. intermedius, and both male and female gametophytes of D. robustus and D. marginatus. The arrangement and structure of sporangia and gametangia have been intensively studied and many reproductive characters not previously used in species discrimination have been incorporated into species' descriptions and used to develop species' concepts. Species are delimited on the following combination of characters: arrangement, size and structure of sporangia, arrangement and structure of gametangia, and the number of medullary cell layers.

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Ruano, Sofía, Andrea Seral, Rubén Vázquez, Sonia Molino, and José María Gabriel y Galán. "Gametophytic phase of the Indonesian ferns Amblovenatum immersum (Blume) Mazumdar and Christella subpubescens (Blume) Holttum (Thelypteridaceae)." Botanica Complutensis 45 (May 10, 2021): e73379. http://dx.doi.org/10.5209/bocm.73379.

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The gametophytic generation of Amblovenatum immersum and Christella subpubescens (Thelypteridaceae), including spore germination, morphological development of the gametophytes, major vegetative features and reproduction strategies, was studied. For both species, the spore germination was of the Vittaria type and the developmental pattern was of the Drynaria type. Adult gametophytes were cordate and hairy, with unicellular and secretory hairs located in the margins and both the ventral and dorsal surfaces of the prothalli. C. subpubescens has another type of acicular hairs only in the margin of the prothallus. Gametangia were of the normal type described for leptosporangiate ferns. In A. immersum all the gametophytes were female. In C. subpubescens the gametophytes produced at first instance female gametangia and then became bisexual with time. Antheridiogen activity was observed in both species, suggested by the presence of small young ameristic gametophytes with antheridia surrounding well-developed female ones.

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Podunay, Yulia A., Nickolai A. Davidovich, and Olga I. Davidovich. "Sexual reproduction of Entomoneis cf. paludosa (Bacillariophyta)." Issues of modern algology (Вопросы современной альгологии), no. 2(20) (2019): 194–96. http://dx.doi.org/10.33624/2311-0147-2019-2(20)-194-196.

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Sexual reproduction and the life cycle of the marine pennate diatom Entomoneis cf. paludosa are described. The reproduction in this species is characterized by morphological and behavioral isogamy. Two gametangia are involved in the sexual process, each of which produces two gametes.

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Ashton, N. W., and M. V. S. Raju. "The distribution of gametangia on gametophores ofPhyscomitrella (Aphanoregma) patensin culture." Journal of Bryology 22, no. 1 (January 2000): 9–12. http://dx.doi.org/10.1179/jbr.2000.22.1.9.

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Mendoza-Ruiz, Aniceto, and Blanca Pérez-García. "Comparative analysis of the sexual phase of Phanerophlebia (Dryopteridaceae) in Mexico." Canadian Journal of Botany 81, no. 5 (May 1, 2003): 501–16. http://dx.doi.org/10.1139/b03-044.

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A comparative analysis is presented of the spore morphology, germination pattern, and prothallial development of the sexual phase of seven species in the fern genus Phanerophlebia C. Presl. Gametophyte development was studied from samples grown both on agar and soil. Spores are monolete, ellipsoid, with light brown to dark brown perine; the germination pattern is Vittaria-type and the prothallial development is Aspidium-type in all of the species. The gametangia are of the type typical for leptosporangiate ferns. Gametophytes of all species initially become female, then bisexual. Differences among species include spore germination time (612 days), shape of the gametophytes (spatulatecordiform to cordiformreniform, with smooth to very irregular margins), development time of trichomes (1224 days), and appearance of gametangia (40200 days). Some species develop the first leaves of the sporophytes after 200 days. Results are contrasted with previously published reports on gametophyte development in Arachniodes Blume, Cyrtomium C. Presl, Didymochlaena Desv., Dryopteris Adans, Olfersia Raddi, Polystichum Roth, and Stigmatopteris C. Chr.Key words: Dryopteridaceae, fern gametophyte, Mexico, morphogenesis, Phanerophlebia, sexual phase.

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Nahor, Omri, Cristina F. Morales-Reyes, Gianmaria Califano, Thomas Wichard, Alexander Golberg, and Álvaro Israel. "Flow cytometric measurements as a proxy for sporulation intensity in the cultured macroalga Ulva (Chlorophyta)." Botanica Marina 64, no. 2 (March 31, 2021): 83–92. http://dx.doi.org/10.1515/bot-2020-0050.

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Abstract Controlling the life cycle of the green macroalga Ulva (Chlorophyta) is essential to maintain its efficient aquaculture. A fundamental shift in cultivation occurs by transforming the thallus cells into gametangia and sporangia (sporulation), with the subsequent release of gametes and zoids. Sporulation occurrence depends on algal age and abiotic stimuli and is controlled by sporulation inhibitors. Thus, quantification of sporulation intensity is critical for identifying the biotic and abiotic factors that influence the transition to reproductive growth. Here, we propose to determine the sporulation index by measuring the number of released gametes using flow cytometry, in proportion to the total number of thallus cells present before the occurrence of the sporulation event. The flow cytometric measurements were validated by manually counting the number of released gametes. We observed a variation in the autofluorescence levels of the gametes which were released from the gametangia. High autofluorescence level correlated to phototactically active behaviour of the gametes. As autofluorescence levels varied between different groups of gametes related to their mobility, flow cytometry can also determine the physiological status of the gametes used as feedstock in seaweed cultivation.

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Naz, Sabrina, and Nasrin Jahan Diba. "Some Morphological Observations of Charophytes (Characeae) from Bangladesh." Journal of Life and Earth Science 7 (August 22, 2014): 71–77. http://dx.doi.org/10.3329/jles.v7i0.20124.

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Morphologically interesting charophytes were found from Chapai-Nawabgonj and Rajshahi districts in Bangladesh. These are: swollen branchlet of Lamprothamnium papulosum (Wallr.) J. Groves, long stalked gametangia and twin antheridia of Nitella hyalina (DC.) Agardh, bifid bract cells of Chara flaccida A. Braun and bifid end cell of Nitellopsis obtusa (Desv.) J. Groves. DOI: http://dx.doi.org/10.3329/jles.v7i0.20124 J. Life Earth Sci., Vol. 7: 71-77, 2012

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Berger-Perrot, Y., J.-CI Thomas, and M.-Th L'Hardy-Halos. "Gametangia, gametes, fertilization and zygote development in Ulothrix flacca var. roscoffensis (Chlorophyta)." Phycologia 32, no. 5 (September 1993): 356–66. http://dx.doi.org/10.2216/i0031-8884-32-5-356.1.

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12

Muccifora, S., M. Lorito, and P. Gori. "An electron microscope study of gametangia in the green seaweed Halimeda tuna." Giornale botanico italiano 128, no. 6 (January 1994): 975–80. http://dx.doi.org/10.1080/11263509409436464.

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Stratmann, Johannes, Georg Paputsoglu, and Wolfgang Oertel. "DIFFERENTIATION OF ULVA MUTABILIS (CHLOROPHYTA) GAMETANGIA AND GAMETE RELEASE ARE CONTROLLED BY EXTRACELLULAR INHIBITORS1." Journal of Phycology 32, no. 6 (December 1996): 1009–21. http://dx.doi.org/10.1111/j.0022-3646.1996.01009.x.

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14

Hedenäs, Lars, and Irene Bisang. "Episodic but ample sporophyte production in the moss Drepanocladus turgescens (Bryophyta: Amblystegiaceae) in SE Sweden." Acta Musei Silesiae, Scientiae Naturales 68, no. 1-2 (July 1, 2019): 83–93. http://dx.doi.org/10.2478/cszma-2019-0009.

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Abstract In the Baltic area, the long-lived dioicous wetland moss Drepanocladus turgescens (T.Jensen) Broth. produces sporophytes rarely and at irregular intervals. Based on surveys of sporophyte occurrences at 13 sites in two regions in northern Gotland (Sweden) during three to five years, we ask: (1) Is sporophyte formation associated with precipitation and a precipitation index that considers the dry periods during July-August of the preceding year, when gametangia are formed and fertilization occurs? (2) Does the estimated spore output suffice for the species’ long-term persistence of the (Northern) European population species? In one of the study regions, where D. turgescens occurs in depressions, sporophyte formation was associated with the two precipitation parameters. In the other study region, with relatively higher precipitation and exposed occurrences on a slightly sloping bedrock with very little accumulated soil, no such association existed. We suggest that this lack of weather effects results from that the exposed rock habitat requires longer continuously wet periods than the depression habitat to allow for gametangia initiation and development, and fertilisation. Average spore production for six spore capsules, from three Gotland localities was 181,000. Based on the sporophyte counts during the survey years, we estimated the total reproductive output as 411.5 million spores in 2013, and 42.5 million in 2015, in the two respective study regions. Taken together with data on haplotype patterns and considering observations on recent colonisations, we argue that such a relatively low and episodic regional spore production is sufficient to maintain global populations of long-lived species, even if these occur in specialized and geographically restricted habitats.

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Farfán-Santillán, Norberto, Aniceto Mendoza-Ruiz, Blanca Pérez-García, and Ernesto Velázquez-Montes. "Desarrollo de los gametofitos de especies mexicanas de Gleicheniaceae." Revista de Biología Tropical 65, no. 3 (April 20, 2017): 939. http://dx.doi.org/10.15517/rbt.v65i3.26346.

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In Mexico, the Gleicheniaceae family is represented by different species such as Dicranopteris flexuosa, Diplopterygium bancroftii, Gleichenella pectinata, Sticherus bifidus, S. brevipubis, S. palmatus and S. underwoodianus. Currently, few studies have described the gametophytes of some species in this family, and our objective was to contribute to the knowledge, and to describe and compare different aspects of their germination, gametophyte development, and to determine if the prothallus characters are useful for taxonomic delimitations in the group. For this purpose, specimens and spores of each taxon were collected in the field, spores were sown in Petri dishes containing agar and Thompson nutrient medium, and grown in a plant growing chamber under controlled conditions of light (12 hr light/darkness), (50 %) humidity, and temperature (18 °C night, 25 °C day). Additionally, observations of fresh materials were made and photomicrographs were taken using both optical and scanning electron microscopes. Our observations allowed distinguishing two types of germination Gleichenia and Cyathea; and three types of prothallial development Marattia, Osmunda and Drynaria. Gametangia presented more than three cells, and this is considered a primitive feature by other authors. As some variations in the germination type were observed and have not previously been reported in the literature for this family, and because of the heterogenity in the patterns of the prothallial cell development, and gametangia of more than four cells, it is important to broaden the study to other species, in order to determine the taxonomic value of the morphological characters of the gametophyte, as well as to determine if these variations are present in other species of the family.

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LI, YUHANG, HIDEKAZU SUZUKI, TAMOTSU NAGUMO, and JIRO TANAKA. "Auxosporulation, morphology of vegetative cells and perizonium of Fallacia tenera (Hust.) D.G. Mann (Bacillariophyceae)." Phytotaxa 164, no. 4 (April 11, 2014): 239. http://dx.doi.org/10.11646/phytotaxa.164.4.3.

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Specimens of Fallacia tenera were collected from the surface sediment at in a river estuary in Japan. Auxosporulation occurred in a rough culture. Morphological structures of vegetative cells and auxospores were observed in detail. The vegetative cells have one H-shaped chloroplast. The striae were interrupted by two depressed lateral sterna internally and partly covered by a finely porous conopeum on the external surface. The lateral sterna and porous conopea formed two more or less curved longitudinal canals connecting with the exterior via opening pores on both sides of a terminal fissure. This combination of characteristics is unique to the genus Fallacia. The cingulum was composed of three bands, such as an open valvocupula and two comparatively thin pleurae. The two pleurae could be distinguished by the shape of their ligulae. The second band had a triangular ligula, whereas the ligula of the third band is arc-shaped. The auxosporulation was type IA1a in Geitler’s classification. Two paired gametangia formed two anisogametes in each of them. Two auxospores formed in the thecae of the gametangia after a trans physiological anisogamy. The perizonium of the auxospore consisted of a set of transverse bands and five longitudinal bands. The primary transverse band was about twice wider than the secondary ones. The circular incunabular scales were present on the two terminals of the auxospore and on the surface of the primary transverse band. The primary longitudinal band had an acute terminal and was flanked by secondary longitudinal bands. Each side had two secondary longitudinal bands. All longitudinal bands were immediately beneath the transverse bands. Morphological comparison between Fallacia and Pseudofallaica, and the taxonomic position of F. tenera is also discussed.

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BARCELONA, JULIE F., and PIETER B. PELSER. "Phanerosorus (Matoniaceae), a new fern genus record for the Philippines." Phytotaxa 170, no. 2 (May 22, 2014): 133. http://dx.doi.org/10.11646/phytotaxa.170.2.6.

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The fern family Matoniaceae C. Presl (1847: 32) is a small group composed of only two genera, Matonia R. Brown in Wallich (1829: 16) and Phanerosorus Copeland (1909: 344) with three or four species characterized by rhizomes with polycyclic solenosteles covered with thick uniseriate hairs, anastomosing veins in fertile parts of the lamina, peltate and fugacious indusia, relatively large sporangia and gametangia, and tetrahedral, trilete spores (Kramer 1990, Kato & Setoguchi 1998). The two genera differ from each other in leaf architecture (pedate in Matonia and pinnate in Phanerosorus), habit, and habitat preferences (Phanerosorus pendent and obligately calcicolous and Matonia erect and preferring exposed, sometimes mineralized ridges of high mountains; Kato & Iwatsuki 1985, Barcelona et al. 1996).

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Rolleri, C. H., C. Prada, J. M. Gabriel y Galán, L. M. Passarelli, and M. M. Ciciarelli. "Morphology of the sporophyte and gametophyte of the swamp fern, Blechnum serrulatum (Blechnaceae, Pteridophyta)." Australian Journal of Botany 58, no. 6 (2010): 508. http://dx.doi.org/10.1071/bt09238.

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In the present paper, we provide a revised, comprehensive description of the sporophyte and gametophyte of the swamp fern, Blechnum serrulatum Rich., from neo- and paleotropical localities. External and internal characters of the sporophyte were analysed, including axes, laminae, pinnae, indusia and spores. Intercellular pectic connections of the parenchyma of the rhizomes are reported for the first time. In stipes, cell walls of the aerenchyma tissue contain filamentous protuberances that are composed primarily of cellulose but contain also fatty substances. The morphology of the gametophyte, from spore germination to gametangia formation, is discussed. The taxonomic significance of the characters is considered, especially in regard to the relationship between B. serrulatum and the closely related B. indicum.

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Phillips, J. A., and M. N. Clayton. "Biflagellate spermatozoids in the Dictyotales: the structure of gametes and gametangia in Zonaria angustata (Dictyotales, Phaeophyta)." Phycologia 30, no. 2 (March 1991): 205–14. http://dx.doi.org/10.2216/i0031-8884-30-2-205.1.

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Quodt, Vanessa, Wolfram Faigl, Heinz Saedler, and Thomas Münster. "The MADS-domain protein PPM2 preferentially occurs in gametangia and sporophytes of the moss Physcomitrella patens." Gene 400, no. 1-2 (October 2007): 25–34. http://dx.doi.org/10.1016/j.gene.2007.05.016.

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21

Elwy, Esmat Elwy Aly. "Effect of plant growth regulators on growth and reproduction in the fungus Dipodascopsis uninucleata." Canadian Journal of Botany 67, no. 8 (August 1, 1989): 2425–28. http://dx.doi.org/10.1139/b89-311.

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Different concentrations of IAA, GA3, 4CPA, kinetin, and 2,4-D were used to study their effect on growth and reproduction in Dipodascopsis uninucleata. Most of the concentrations of IAA, kinetin, and 2,4-D tested promoted growth, whereas GA3 had no effect. All substances used stimulated lateral branch formation and 2,4-D had the greatest effect. Most concentrations of the growth regulators either inhibited or had no effect on ascus formation; only 10−8 M 4CPA, 10−6 M 2,4-D, and 10−6 M GA3 enhanced ascus formation. The percentage of hyphae with aborted gametangia increased in cultures treated with most concentrations of the tested substances except 10−8 M 4CPA, which decreased the percentage of failure. Also, growth regulators either delayed or had no effect on sporulation.

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Casanova, Michelle T., and Kenneth G. Karol. "A revision of Chara sect. Protochara, comb. et stat. nov. (Characeae: Charophyceae)." Australian Systematic Botany 27, no. 1 (2014): 23. http://dx.doi.org/10.1071/sb13016.

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A revision of a group of ecorticate species of Chara is presented, on the basis of fresh, pressed and spirit-preserved material. The following seven species are recognised, characterised by a very simple morphology, with few or inconspicuous accessory cells (cortication, stipulodes, bract cells, bracteoles) and large gametangia: Chara australis R.Br., C. lucida (A.Braun) Casanova & Karol comb et. stat. nov., C. porteri Casanova, sp. nov., C. protocharoides Casanova & Karol, nom. nov. (=Protochara australis Womersley & Ophel) and C. stuartiana (Kütz.) Casanova & Karol comb. et. stat. nov. from Australia, and C. corallina Klein ex Willd. and C. wallichii A.Braun from Asia. A new section, Chara subg. Charopsis sect. Protochara (Womersley & Ophel) Casanova & Karol, comb. et stat. nov., is erected to accommodate these taxa, formerly placed in sect. Charopsis.

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Mandoli, Dina F., Adam Wexler, Jill Teschmacher, and Annette Zukowski. "BRIEF INCUBATION OF GAMETANGIA-BEARING CAPS IN ANTIBIOTICS ELIMINATES BRANCHING IN PROGENY OF ACETABULARIA ACETABULUM (CHLOROPHYTA)1." Journal of Phycology 31, no. 5 (October 1995): 844–48. http://dx.doi.org/10.1111/j.0022-3646.1995.00844.x.

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ROMANOV, ROMAN E., and SHAMIL R. ABDULLIN. "Chara kirghisorum (Charales): lectotypification, first reliable record in Europe and update of species distribution in Russia." Phytotaxa 362, no. 2 (July 24, 2018): 220. http://dx.doi.org/10.11646/phytotaxa.362.2.8.

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Charophytes are commonly easily recognizable plants irrespective of their size due to the recurrent combination of very similar parts within their thalli. A few species are outstanding due to their unusual whip-like appearance with regularly distributed small nodules on the stems formed with whorls of short and nearly rudimentary branchlets. The central and north-European Chara filiformis A. Braun in Hertzsch (1855: 81) and mainly Middle-Asian C. kirghisorum Lessing (1834: 212) are examples of this distinctive habit. The species differ essentially in gametangia arrangement as well as in their distribution range. Monoecious C. filiformis does not have reliable records east of Pskov Oblast of Russia (29° E), while dioecious C. kirghisorum is unknown west of Orenburg Oblast of Russia (58° E) (Hollerbach 1941; Hollerbach & Krassavina 1983; LE!, PSK!). Therefore, they may be recognized as vicariate species.

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DUCKETT, JEFFREY G., and SILVIA PRESSEL. "The Colorful Phenology of Five Common Terricolous Mosses in London, England." Bryophyte Diversity and Evolution 39, no. 1 (July 24, 2017): 44. http://dx.doi.org/10.11646/bde.39.1.8.

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Other than general statements about ‘fruiting’ seasons, published floras provide little or no instructive information on moss phenology. Moreover, detailed primary data on reproductive cycles are limited to a very few mosses and remain unknown for the majority of the commonest species. Thus we recorded, over a three year period, the reproductive stages of five very common mosses (Bryum capillare, B. radiculosum, Grimmia pulvinata, Schistidium crassipilum and Tortula muralis) growing on walls in London, England, relying throughout on freshly observed materials rather than dried specimens used in most previous studies. In addition to all the stages visible to the naked eye, which we photographed at regular intervals, specimens were examined microscopically for the presence of viable gametangia, young embryos and the condition of the stomata. Each species had its own distinct phenology and an unique sequence of capsule colour changes. In the two Bryum species, gametangium ontogeny, followed by fertilization, takes place in the spring but the embryos remain dormant until the autumn whereas these stages are autumnal in Grimmia pulvinata, Schistidium crassipilum and Tortula muralis with sporophyte development following immediately. Most stages in sporophyte ontogeny occur over the winter months. The time from embryo formation to spore release ranges from over fifteen months in the two Bryum species down to eight months in Schistidium. In all but this last species there is a delay of up to several months between sporophyte maturation and spore release. In Bryum, hygroscopic movements of the annular cells following heavy rain eventually leads to lid shedding. Over the three years of this study the reproductive cycles were generally the same except that damp weather in the autumn promoted capsule expansion in Grimmia and Schistidium and warm dry weather in the spring hastened capsule maturation in Bryum. Whatever the weather conditions, the stomata of the two Bryum species, Grimmia and Tortula were always open suggesting a primary role in capsule desiccation leading to spore discharge rather than the regulation of gaseous exchange.

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Shaw, Jonathan A., Richard E. Andrus, and Blanka Shaw. "Sphagnum beringiense sp. nov. (Bryophyta) from Arctic Alaska, Based on Morphological and Molecular Data." Systematic Botany 33, no. 3 (July 1, 2008): 469–77. http://dx.doi.org/10.1600/036364408785679842.

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A new species of Sphagnum section Subsecunda, S. beringiense, is described from arctic Alaska from the vicinity of Barrow along the northern coast. The species is distinguished morphologically by the light, yellow-green color of the gametophytes, multistratose stem cortex with 2–4 layers of enlarged thin-walled cells, round, medium-size (ca. 5 μm diameter) outer branch leaf pores, scattered inner branch leaf pores, typically few outer stem leaf pores, and abundant, round to elliptic inner stem leaf pores. Two unique plastid DNA haplotypes occur among Barrow area plants of S. beringiense, and these differ by a minimum of three nucleotide substitutions from those of other Alaskan Sphagnum species in the section Subsecunda. Microsatellite markers show that S. beringiense is genetically variable despite the fact that all plants were sampled from within an area of a few km2 and neither gametangia nor sporophytes have been observed. A key to the six Alaskan species of Sphagnum section Subsecunda is provided.

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Whittier, Dean P. "Induced apogamy in Tmesipteris (Psilotaceae)." Canadian Journal of Botany 82, no. 6 (June 1, 2004): 721–25. http://dx.doi.org/10.1139/b04-049.

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Gametophytes of Tmesipteris lanceolata Dang., which are mycorrhizal in nature, were grown in axenic culture. If cultured in the light on a nutrient medium containing minerals and 0.5% glucose, they did not become photosynthetic; however, about 15% of them produced apogamous sporophytes with stems and microphylls. The gametophytesporophyte junction had a direct connection between the gametophyte and sporophyte tissues and lacked a foot, which is typical for apogamy. Gametangia were limited to the gametophyte portions of these gametophytesporophyte growths, and the vascular tissue was present only in the sporophyte regions. The apogamous aerial stems had the normal anatomy for a sporophyte, with vascular tissue, epidermal cells, stomata, and chlorenchyma. The origin of the apogamous sporophytes was different from the origin in fern gametophytes. The Tmesipteris sporophytes arose terminally from the gametophyte apices. It appears that the apical meristem of the gametophyte is converted to a shoot apical meristem to form the apogamous aerial shoot.Key words: Tmesipteris, Psilotaceae, apogamy, sporophyte, gametophyte.

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Krings, Michael, James F. White, Nora Dotzler, and Carla J. Harper. "A Putative Zygomycetous Fungus with Mantled Zygosporangia and Apposed Gametangia from the Lower Coal Measures (Carboniferous) of Great Britain." International Journal of Plant Sciences 174, no. 3 (March 2013): 269–77. http://dx.doi.org/10.1086/668247.

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Katsaros, Chr, G. Kreimer, and M. Melkonian. "Localization of Tubulin and a Centrin-Homologue in Vegetative Cells and Developing Gametangia ofEctocarpus siliculosus(Dillw.) Lyngb. (Phaeophyceae, Ectocarpales)." Botanica Acta 104, no. 2 (April 1991): 87–92. http://dx.doi.org/10.1111/j.1438-8677.1991.tb00201.x.

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Kuroiwa, T., S. Kawano, M. Watanabe, and T. Hori. "Preferential digestion of chloroplast DNA in male gametangia during the late stage of gametogenesis in the anisogamous algaBryopsis maxima." Protoplasma 163, no. 2-3 (June 1991): 102–13. http://dx.doi.org/10.1007/bf01323334.

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BRISCOE, LAURA R. E., NYREE J. C. ZEREGA, H. THORSTEN LUMBSCH, MICHAEL STECH, EKAPHAN KRAICHAK, MATTHEW J. VON KONRAT, JOHN J. ENGEL, and NORMAN J. WICKETT. "Molecular, morphological, and biogeographic perspectives on the classification of Acrobolboideae (Acrobolbaceae, Marchantiophyta)." Phytotaxa 319, no. 1 (August 29, 2017): 56. http://dx.doi.org/10.11646/phytotaxa.319.1.2.

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The liverwort subfamily Acrobolboideae has historically contained the three genera: Acrobolbus, Marspidium, and Tylimanthus. Generic delimitations in this subfamily have been historically inferred from morphological characters, specifically the location of gametangia. Taxonomists have had difficulty separating the genera, with some combining Tylimanthus and Acrobolbus, whereas others merged Marsupidium and Tylimanthus. We used five chloroplast loci to reconstruct a phylogeny of the group, revealing all three genera are polyphyletic as currently described. An assessment of key morphological characters used to separate genera in the subfamily resulted in several observations: characters used to circumscribe Acrobolbus were homoplasious; characters used to circumscribe each genus (e.g., the placement of female reproductive organs) do not reflect phylogenetic relationships; and the evolutionary trajectories of some characters (i.e., the number of antheridia, male reproductive organs, per male bract) correspond directly with previous evolutionary hypotheses for the family, but do not follow historical taxonomic inferences. Irrespective of generic concepts, several well–supported clades within the phylogeny have a strong biogeographic structure. Using these lines of evidence, we recognize Acrobolbus as a single genus in Acrobolboideae.

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Horinouchi, Yusuke, and Tatsuya Togashi. "Within-clutch variability in gamete size arises from the size variation in gametangia in the marine green alga Monostroma angicava." Plant Reproduction 31, no. 2 (February 1, 2018): 193–200. http://dx.doi.org/10.1007/s00497-018-0323-8.

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Boutet, Xavier, Frédéric Laurent, and Anne Chandelier. "Influence of the medium-solidifying agent, the nutrient, and the genotype on the production of gametangia by Phytophthora ramorum in vitro." Mycological Research 113, no. 1 (January 2009): 110–16. http://dx.doi.org/10.1016/j.mycres.2008.09.001.

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Brooks, Fred, Fabio Rindi, Yasuo Suto, Shuji Ohtani, and Mark Green. "The Trentepohliales (Ulvophyceae, Chlorophyta): An Unusual Algal Order and its Novel Plant Pathogen—Cephaleuros." Plant Disease 99, no. 6 (June 2015): 740–53. http://dx.doi.org/10.1094/pdis-01-15-0029-fe.

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Most plant pathologists know certain algae can be used as gelling agents in culture media. Pathologists practicing in tropical or subtropical environments also know that some algae damage plants. The five genera in the order Trentepohliales (Chlorophyta) are unique and fascinating. Among other characteristics, they are subaerial, bright orange to red in color, and one genus, Cephaleuros, is a plant pathogen while another, Stomatochroon, is a space parasite. Cephaleuros causes algal spot and includes 17 accepted species. Of these, 13 develop between the cuticle and the epidermis of their hosts and four grow intercellularly. The latter are especially damaging, causing chlorosis and branch dieback. Zoospores and gametes germinate on plant surfaces during the rainy season and probably penetrate through breaks in the host cuticle. Their filamentous growth forms thalli that produce sporangiophores and spherical gametangia the following year. Several species of Cephaleuros have a broad host range and though their damage is usually superficial, it can be economically important on certain crops. Plant stress is the greatest predisposing factor to this algal disease. Management includes providing plants with sufficient moisture and nutrients, modifying cultural and harvesting practices, and planting resistant cultivars when available.

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Van Onsem, Stijn, and Ludwig Triest. "Trading offspring for survival: high duckweed cover decreases reproductive potential and stimulates elongation in the submerged macrophyte Chara globularis Thuillier." Hydrobiologia 848, no. 11 (May 9, 2021): 2667–80. http://dx.doi.org/10.1007/s10750-021-04577-y.

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AbstractCompact blankets of free-floating plants generate stressful aquatic environments. The response of submerged macrophytes remains largely elusive. Will they rush toward the light or rather speed up reproductive efforts and escape using propagules—the macrophyte equivalent of lifeboats? We studied the effects of complete duckweed (Lemna minor) cover on growth and reproductive fitness of macroalga Chara globularis in a pond mesocosm experiment. C. globularis growing in Lemna-covered plots lost biomass and developed longer internodes, indicating an elongative reflex to escape stress. Densities of reproductive organs per biomass unit evolved positively in open plots and negatively in covered plots, suggesting a trade-off between reproductive effort and vegetative elongation. Reproductive potential correlated significantly with incident radiation. Lemna cover, however, did not affect oospore rain—at least within the limited time span of propagule trapping. C. globularis thus displayed an ability to modify phenology in response to floating plant stress, allocating resources to internodes instead of gametangia. Nevertheless, duckweed dominance clearly suppressed the overall reproductive performance of C. globularis. The regenerative capacity of many submerged macrophytes will likely suffer from increased floating plant dominance due to global warming—unless efforts are made to reduce nutrient levels in vulnerable waterbodies.

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Soulié-Märsche, Ingeborg. "Extant Gyrogonite Populations of Chara zeylanica and Chara haitensis: Implications for Taxonomy and Palaeoecology." Australian Journal of Botany 47, no. 3 (1999): 371. http://dx.doi.org/10.1071/bt97131.

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Chara zeylanica (Klein ex Willdenow) R.D.Wood is known to develop populations which display either four- or eight-scutate antheridia. Despite only minor differences in the vegetative features, plants with these two types of male gametangia proved to be reproductively isolated and C. haitensis Turpin was validated as the correct name for the octoscutate plants (Proctor et al. 1971). Here we provide data for the calcified female reproductive organs (gyrogonites) of both species in order to determine whether they can be distinguished or not. Ten populations from both field collections and culture material were studied. The morphological characteristics of the gyrogonites were determined on the basis of measurements of 100 specimens for each population. The gyrogonites of four- and eight-scutate plants proved to be significantly different and thus enhanced separation at species level. Ecology, biogeography and the possible phylogenetic relationships of the taxa are discussed. Unlike C. zeylanica, which displays worldwide distribution within the tropical belt, the modern distribution of C. haitensis seems hitherto restricted to the American continent. Within this area, C. zeylanica grows preferentially in permanent lakes whereas C. haitensis is only found in temporary water bodies. Given these different ecological requirements, the fossil record of both taxa, determined from their specific gyrogonite morphology, can provide information about the nature of ancient lake-ecosystems particularly useful for Quaternary studies in the Americas.

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Casanova, Michelle T. "Lamprothamnium in Australia (Characeae, Charophyceae)." Australian Systematic Botany 26, no. 4 (2013): 268. http://dx.doi.org/10.1071/sb13026.

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Charophytes in the genus Lamprothamnium exhibit a large amount of diversity, particularly in the examples from Australia, although little of that variation has been recognised at species level in the past. The Australian members of the genus are revised here on the basis of extensive new collections, examination of specimens in herbaria and comprehensive review of the literature and available type material. The existing species Lamprothamnium macropogon (A.Braun) Ophel, L. inflatum (Fil. & G.O.Allen ex Fil.) A.García & Karol and L. heraldii A.García & Casanova are retained, eight new species are described (L. australicum Casanova, L. beilbyae Casanova, L. capitatum Casanova, L. compactum Casanova, L. coorongense Casanova, L. diminutum Casanova, L. macroanthum Casanova and L. stipitatum Casanova) and two taxa variously treated at infraspecific rank in Lychnothamnus are transferred to Lamprothamnium at species rank (L. cockajemmyense Casanova, L. tasmanicum (A.Braun) Casanova). Neither L. papulosum (Wallr.) J.Groves nor L. succinctum (A.Braun) R.D.Wood are confirmed for Australia after examination of the type material of these species. Species are distinguished by the arrangement of the gametangia, morphology of the fertile whorls and characteristics of the oospores. Four of these species are dioecious and nine are monoecious, which supports published conjectures concerning the biogeography of charophyte species (Proctor (1980): J. Phycol. 16, 218–233, doi:10.1111/j.1529-8817.1980.tb03023.x).

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Casanova, Michelle T. "Corrigendum to: Lamprothamnium in Australia (Characeae, Charophyceae)." Australian Systematic Botany 26, no. 6 (2013): 475. http://dx.doi.org/10.1071/sb13026_co.

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Charophytes in the genus Lamprothamnium exhibit a large amount of diversity, particularly in the examples from Australia, although little of that variation has been recognised at species level in the past. The Australian members of the genus are revised here on the basis of extensive new collections, examination of specimens in herbaria and comprehensive review of the literature and available type material. The existing species Lamprothamnium macropogon (A.Braun) Ophel, L. inflatum (Fil. & G.O.Allen ex Fil.) A.García & Karol and L. heraldii A.García & Casanova are retained, eight new species are described (L. australicum Casanova, L. beilbyae Casanova, L. capitatum Casanova, L. compactum Casanova, L. coorongense Casanova, L. diminutum Casanova, L. macroanthum Casanova and L. stipitatum Casanova) and two taxa variously treated at infraspecific rank in Lychnothamnus are transferred to Lamprothamnium at species rank (L. cockajemmyense Casanova, L. tasmanicum (A.Braun) Casanova). Neither L. papulosum (Wallr.) J.Groves nor L. succinctum (A.Braun) R.D.Wood are confirmed for Australia after examination of the type material of these species. Species are distinguished by the arrangement of the gametangia, morphology of the fertile whorls and characteristics of the oospores. Four of these species are dioecious and nine are monoecious, which supports published conjectures concerning the biogeography of charophyte species (Proctor (1980): J. Phycol. 16, 218–233, doi:10.1111/j.1529-8817.1980.tb03023.x).

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Bakonyi, J., and T. Érsek. "First Report of the A2 Mating Type of Phytophthora infestans on Potato in Hungary." Plant Disease 81, no. 9 (September 1997): 1094. http://dx.doi.org/10.1094/pdis.1997.81.9.1094d.

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Severe symptoms of potato late blight were observed in July 1996 on potato (Solanum tuberosum L.) cv. Desirée grown on a farm in western Hungary. Isolation was made directly from diseased leaf tissues onto selective pea-agar medium. A recovered isolate, H2a, was identified as Phytophthora infestans (Mont.) de Bary on the basis of Koch's postulates and morphological characteristics of the fungus. Pairing of H2a with isolates of known mating types, A1 and A2 from Germany, revealed that it represents the A2 mating type. After a 2-week incubation on pea-agar medium at 20°C, oospores formed in abundance in the region of contact between the colonies of H2a and the A1 mating type isolate. After extended incubation scattered formation of gametangia was observed when isolate H2a had been paired with itself or with the A2 mating type isolate. The same phenomenon of presumed self fertilization also took place when single, zoospore-derived colonies of H2a were combined with one another or with the known A2 isolate. Of an incomplete set of potato differentials, leaves of potato genotypes r, R2, R3, R4, R1.2.3.4, R7, R8, and R11 were all susceptible to infection with a zoospore suspension of the isolate H2a. The complex virulence phenotype of H2a, its tolerance to metalaxyl in agar cultures and on leaf disks (EC50 >100 mg liter-1), and its A2 mating type behavior collectively suggest that H2a represents a genotype that recently has been introduced into Hungary.

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Park, Sang Hee, Jung Sung Kim, and Hyoung Tae Kim. "A Small Number of Gametophytes with Gametangia and Stunted Sporophytes of Antrophyum obovatum Baker (Pteridaceae): The Suppression of Functional Sporophyte Production by Prezygotic and Postzygotic Sterility." Plants 10, no. 1 (January 18, 2021): 170. http://dx.doi.org/10.3390/plants10010170.

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Ferns have conspicuous sporophytes as the dominant phase in their life cycle; however, the gametophytes are completely separated from the sporophytes and supply their own nutrition, unlike in bryophytes and seed plants. Among the gametophytes, some maintain their populations in the gametophyte phase without progressing to sporophyte production and are known as independent gametophytes. Independent gametophytes of Antrophyum obovatum Baker were recently reported in one population on Jeju Island, Korea. In the present study, we surveyed more places to find new independent gametophyte populations of A. obovatum using the rbcL gene sequence-based DNA barcoding technique. We identified two new sites inhabited by independent gametophytes. Archegonia and juvenile sporophytes were independently observed in each location under slightly different environmental conditions. Consequently, in the case of this species, functional sporophyte production is likely suppressed by prezygotic and postzygotic sterility, depending on microenvironmental factors.

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Derviş, Sibel, Şahimerdan Türkölmez, Osman Çiftçi, Göksel Özer, Çiğdem Ulubaş Serçe, and Murat Dikilitas. "Phytopythium litorale: A Novel Killer Pathogen of Plane (Platanus orientalis) Causing Canker Stain and Root and Collar Rot." Plant Disease 104, no. 10 (October 2020): 2642–48. http://dx.doi.org/10.1094/pdis-01-20-0141-re.

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Decline symptoms associated with lethal stem and branch canker stain along with root and collar rots were observed on 5- to 7-year-old roadside oriental plane trees (Platanus orientalis) in Diyarbakır, Turkey. Above-ground symptoms included leaf necrosis, leaf curling, extensive bluish or blackish staining of shoots, branches, stem bark, and wood surfaces, as well as stem cankers and exfoliation of branch bark scales. A general decline of the trees was distinctly visible from a distance. A Phytophthora/Pythium-like oomycete species with globose to ovoid, often papillate and internally proliferating sporangia was consistently isolated from the fine and coarse roots and stained branch parts and shoots. The pathogen was identified as Phytopythium litorale based on several morphological features. Partial DNA sequences of three loci, including nuclear rDNA internal transcribed spacer (ITS) and the large ribosomal subunit (LSU), and mitochondrial cytochrome c oxidase subunit II (coxII) confirmed the morphological identification. All P. litorale isolates were homothallic, developing gametangia, ornamented oogonia with elongate to lobate antheridia. Pathogenicity of P. litorale was tested by inoculation on excised shoots and by root inoculation on seedlings. P. litorale produced large lesions and blights on shoots in just 5 days and killed 100% of the seedlings in a month. This paper presents the first confirmed report of P. litorale as an important pathogen on a plant species causing branch and stem cankers, and root and collar rot, in and on P. orientalis, resulting in a rapid decline of trees and suggesting a threat to plane.

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Gorrer, Daniel Alejandro, Pedro Cayetano Berrueta, Juan Pablo Ramos Giacosa, Gabriela Elena Giudice, and Marìa Luján Luna. "Morfogénesis de la fase sexual de los helechos epífitos Microgramma mortoniana y Pleopeltis macrocarpa (Polypodiaceae) reserva Natural Punta Lara, Buenos Aires, Argentina." Revista de Biología Tropical 66, no. 3 (July 4, 2018): 1078. http://dx.doi.org/10.15517/rbt.v66i3.31775.

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The Punta Lara Natural Reserve is located on the riverside of the La Plata River in the province of Buenos Aires, Argentina. It is the Southern most relict in the world of subtropical riparian forest. The epiphytic ferns studied in this work belong to the Polypodiaceae family: Microgramma mortoniana and Pleopeltis macrocarpa. Plant communities are subject to high levels of anthropization and introduction of exotic species. The goals of this work are to provide information on the morphogenesis of epiphytic gametophytes and to extend knowledge of their life cycles, contributing to their conservation. Sowing was carried out in Dyer medium. In both species the spores are monolete, ellipsoidal, yellowish and with verrucate sculpture. The equatorial diameter is 60-61 μm, the polar diameter is 39-42 μm. The germination is the Vittaria type; in M. mortoniana occurs at 20 days, while in P. macrocarpa occurs at six days. The filaments are uniseriate of 3-6 cells in length. The gametophyte development is Drynaria type. The cordated form is given after 40 days. In M. mortoniana, buds originated after 40 days. In P. macrocarpa, after 120 days, clathrate trichomes scale-like appear mainly on the margins of the gametophyte. The gametangia are typical of leptosporangiate ferns. The sporophyte of M. mortoniana emerged after 120 days and that of P. macrocarpa arose after 500 days, its blades are simple, spatulate and unicellular and multicellular branching hairs were observed. The germination pattern, gametophyte development, the presence of a lipid globule in the prothalic cell and the formation of unicellular capitated hairs are relevant characters that could be considered for systematic group. The delay in the formation of sporophytes through sexual reproduction, allows us to infer that the success of their establishment in situ would be given by the vegetative reproduction through creeping rhizomes and buds of gametophytes.

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Proctor, Vernon W. "Charophytivory, Playas y Papalotes, a Local Paradigm of Global Relevance." Australian Journal of Botany 47, no. 3 (1999): 399. http://dx.doi.org/10.1071/bt97088.

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The Llano Estacado region of western Texas and adjacent New Mexico has one of the most species-rich charophyte floras known for North America, but upon closer inspection this flora is seen to consist of two, strictly non-overlapping segments, one of 12 taxa, the other of nine. The larger group of species is confined to a vast series of shallow, ephemerally inundated depressions known as playas. These normally fill with run-off rainwater in late May or early June, remain flooded through early to mid-September before eventually drying to the curling polygon stage near the end of September. Approximately 8 months later the cycle is repeated. The remaining nine charophytes are confined to permanently inundated sites, the most common of which are livestock-watering windmill complexes, known as papalotes. Rarely, if ever, are members of the playa-12 encountered in papalotes or members of the papalote-9 in playas. The underlying bases for this ‘two flora’ dichotomy stem from the contrasting amphipod populations engendered by the two habitat types. Most freshwater amphipods (scuds), including the common North American herbivore Hyalella azteca (Saussure), cannot withstand complete desiccation which, accordingly, prevents its colonisation of playas. By contrast, scuds often reach exceptionally high densities in the associated concrete or metal tanques of papalotes, since such specialised habitats are usually free of vertebrate predators, e.g. birds, fish, turtles, salamanders. Scud- resistant charophytes are larger and slower to develop gametangia, features inimical to success in short- lived playas. By contrast, precocious charophyte opportunists–typical of playa floras–cannot withstand the grazing pressures of papalote (or papalote-like) environments. While charophytivory is assumed to be of worldwide occurrence and significance, it has been clearly demonstrated only in the unique juxtaposition of ‘playas y papalotes’.

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Watts, Jacob L., Robbin C. Moran, and James E. Watkins. "Hymenasplenium volubile: documentation of its gametophytes and the first record of a hemiepiphyte in the Aspleniaceae." Annals of Botany 124, no. 5 (October 9, 2019): 829–35. http://dx.doi.org/10.1093/aob/mcz124.

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Abstract Background and Aims Through careful field examination of the growth habit of the gametophytes and sporophytes of Hymenasplenium volubile across an ontogenetic series, we aim to understand better the evolution of epiphytism in this poorly understood group of ferns Methods We made field observations of H. volubile sporophytes and gametophytes, and brought specimens back to the lab for microscopic analysis. In the field, sporophytes at each ontogenetic stage were photographed to document the species’ growth habit. We used an existing phylogeny to optimize growth form of New World Hymenasplenium. Key Results Young sporophytes were at first fully epiphytic and produced one or two long feeding roots that extend to the soil where they branch profusely. The feeding roots remain in contact with the soil throughout the life of the plant. Thus, H. volubile is a hemiepiphyte. While immature, gametophytes are appressed to the tree trunk, but, as their gametangia mature, their lower margin lifts upward, imparting a shelf-like appearance to the thallus. The thallus attaches to the substrate by branched rhizoids produced along the margin of the thallus in contact with the substrate. Conclusions Hemiepiphytes are a key link in the evolution of epiphytic ferns and may act as a bridge between the forest floor and the canopy. Our finding is the first report of hemiepiphytism in Aspleniaceae, a large lineage with many epiphytic and terrestrial taxa. This work serves as an important model to understand the evolution of epiphytism in this group specifically and in ferns in general. The majority of our understanding of fern gametophyte biology is derived from laboratory studies. Our efforts represent a fundamental contribution to understanding fern gametophyte ecology in a field setting.

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Genau, Anne C., Zhanghai Li, Karen S. Renzaglia, Noe Fernandez Pozo, Fabien Nogué, Fabian B. Haas, Per K. I. Wilhelmsson, et al. "HAG1 and SWI3A/B control of male germ line development in P. patens suggests conservation of epigenetic reproductive control across land plants." Plant Reproduction 34, no. 2 (April 11, 2021): 149–73. http://dx.doi.org/10.1007/s00497-021-00409-0.

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Abstract Key message Bryophytes as models to study the male germ line: loss-of-function mutants of epigenetic regulators HAG1 and SWI3a/b demonstrate conserved function in sexual reproduction. Abstract With the water-to-land transition, land plants evolved a peculiar haplodiplontic life cycle in which both the haploid gametophyte and the diploid sporophyte are multicellular. The switch between these phases was coined alternation of generations. Several key regulators that control the bauplan of either generation are already known. Analyses of such regulators in flowering plants are difficult due to the highly reduced gametophytic generation, and the fact that loss of function of such genes often is embryo lethal in homozygous plants. Here we set out to determine gene function and conservation via studies in bryophytes. Bryophytes are sister to vascular plants and hence allow evolutionary inferences. Moreover, embryo lethal mutants can be grown and vegetatively propagated due to the dominance of the bryophyte gametophytic generation. We determined candidates by selecting single copy orthologs that are involved in transcriptional control, and of which flowering plant mutants show defects during sexual reproduction, with a focus on the under-studied male germ line. We selected two orthologs, SWI3a/b and HAG1, and analyzed loss-of-function mutants in the moss P. patens. In both mutants, due to lack of fertile spermatozoids, fertilization and hence the switch to the diploid generation do not occur. Pphag1 additionally shows arrested male and impaired female gametangia development. We analyzed HAG1 in the dioecious liverwort M. polymorpha and found that in Mphag1 the development of gametangiophores is impaired. Taken together, we find that involvement of both regulators in sexual reproduction is conserved since the earliest divergence of land plants.

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Dick, MW. "A technique for teaching: Gametangial production in Mucor." Bulletin of the British Mycological Society 19, no. 2 (October 1985): 134–35. http://dx.doi.org/10.1016/s0007-1528(85)80016-x.

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Lee, Lauren, Todd N. Rosenstiel, and Sarah M. Eppley. "Variation of photoperiod response in moss gametangial formation." Bryologist 113, no. 3 (September 2010): 673–78. http://dx.doi.org/10.1639/0007-2745-113.3.673.

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Raida, Olena, Olha Burova, and Igor Olshanskyi. "New finding of Vaucheria aversa Hassall (Ochrophyta, Xanthophyceae) in Ukraine." Biolohichni systemy 12, no. 1 (June 25, 2020): 105–10. http://dx.doi.org/10.31861/biosystems2020.01.105.

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Vaucheria aversa (Xanthophyta) was recorded for the first time in Ukraine in Sula River, Hydrological Reserve «Artopolot», Poltava Region. It was found in benthos in spring (May 2020) in silty-sandy soil in shallow water. The material was collected and processed according to a common methodology. Sterile samples before the appearance of the gametengians were kept in natural water in petri dishes in well-lit places. This method of «coarse culture», in most cases, allowed to get gametangia within two weeks. The species identification was done with fertile filaments only. 4% formaldehyde solution was used for material fixation. Taxonomic identification of samples was done using a comparative and morphological methods, which includes analysis of morphological variability and verification of the consistency of the studied material with the diagnosis. Thalli of V. aversa are direct, branched, bisexual, 80–90 μm wide. Antheridia are cylindrical, tubular shape, pressed to the filament or slightly raised above it, 119–130 × 41–43 μm. Oogonia erect, sessile, ovoid to subspherical, sometimes placed in pairs, with a curved beak at the front, 190–230 × 140–163 μm. According to morphological characteristics this species is similar to another one from section Tubligerae Walz – V. fontinalis (Linnaeus) T.A. Christensen. Their distinctive and common features are as follows. Filaments of V. fontinalis are narrower (up to 75 μm) than V. aversa (up to 131 μm). Both species are characterized by oogonia grouped together in a row. Antheridia present in quantity 1 or 2 on both sides of oogonia. But the species are very different in size and shape of oogonia: in V. aversa they are sessile, located one at a time or less often two, extended near the base, sharply narrowed at the apex. The beak is directed straight or obliquely up, bent to the side of the oogonia body. In V. fontinalis oogonia are placed in one row, most often in the amount of 1-6, the beak tapers gradually. Anteridia are cylindrical, on short pedicel. V. aversa grew as a part of polyspecies complex of green algae together with representatives of such genera as Cladophora Kützing, Spirogyra Link and Mougeotia C. Agardh. V. aversa is widely distributed in continental water bodies of Europe, Asia and North America, Australia and New Zealand, but is firstly recorded in Ukraine.

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Werres, Sabine, and Daphné De Merlier. "First Detection of Phytophthora ramorum Mating Type A2 in Europe." Plant Disease 87, no. 10 (October 2003): 1266. http://dx.doi.org/10.1094/pdis.2003.87.10.1266c.

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Since its original isolation in 1993, Phytophthora ramorum has become an important pathogen. Initially, it was determined to be the causal agent of a twig blight of Rhododendron spp. in Germany and the Netherlands (3). Around the same period, symptoms and mortality on oak (Quercus spp.) and tanoak (Lithocarpus densiflorus) were associated with P. ramorum in California (2), where the disease was named sudden oak death. Subsequently, P. ramorum has been detected on a wide range of forest trees and shrub species in the United States. In Europe, the pathogen has spread to many countries, primarily on nursery plants of Rhododendron and Viburnum spp., and recently, on Camellia japonica, Kalmia latifolia, Pieris formosa var. forrestii, P. japonica, Leucothoe sp., Syringa vulgaris, and Taxus baccata. P. ramorum has not been observed in European forests. P. ramorum is heterothallic, and initial in vitro mating studies on agar media suggested that only the A1 mating type occurred in Europe, while only the A2 mating type was present in the United States (4). However, an isolate collected in 2002 in Belgium (1) appears to be the A2 mating type. This isolate (CBS 110901, Centraal Bureau voor Schimmelcultures, Baarn, the Netherlands) originated from an imported V. bodnantense plant at an ornamental nursery. A hyphal tip culture (BBA 26/02) of this isolate produced no oogonia on carrot piece agar after 6 weeks in pairing tests with other Phytophthora species of mating type A2. When paired with mating type A1 of P. cambivora, P. cinnamomi, P. cryptogea, and P. drechsleri, however, oogonia were observed in all pairings within 6 weeks. The number of oogonia was low in all pairings but was highest in pairings with P. cryptogea. No oospores were produced after 6 weeks between P. ramorum isolates BBA 26/02 and BBA 9/95 (from the holotype, mating type A1), but gametangia were observed when these isolates were paired on Rhododendron sp. twigs. Normal oogonia were produced on the outgrowing mycelium when pieces from these twigs were placed on carrot piece agar. The shape and size of the oogonia produced on carrot piece agar after pairing with P. cryptogea and on Rhododendron sp. twigs after pairing with P. ramorum BBA 9/95 were similar (24 to 34 μm, mean 29.6 μm and 25 to 33 μm, mean 30.6 μm, respectively). To our knowledge, this is the first observation of P. ramorum mating type A2 in Europe. References: (1) D. De Merlier et al. Plant Dis. 87:203, 2003. (2) D. M. Rizzo et al. Plant Dis. 86:205, 2002. (3) S. Werres et al. Mycol. Res. 105:1166, 2001. (4) S. Werres and B. Zielke. J. Plant Dis. Prot. 110:129, 2003.

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Luongo, L., M. Galli, S. Vitale, A. Haegi, and A. Belisario. "First Report of Phytophthora tropicalis on Rhododendron in Italy." Plant Disease 97, no. 10 (October 2013): 1385. http://dx.doi.org/10.1094/pdis-04-13-0445-pdn.

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Abstract:

The genus Rhododendron comprises over 1,000 species, which represent many important ornamental shrubs. Microbial isolations were made from Rhododendron catawbiense plants showing symptoms of wilt, dieback, and death of shoots obtained from two nurseries in the Latium region in the late summer of 2012. A Phytophthora species was consistently recovered by plating small pieces of stem and collar tissues, cut from the margin of lesions, on P5ARPH selective medium. Pure cultures were obtained by single-hyphal transfers and they grew in a rosaceous pattern on potato dextrose agar (PDA) at an optimum temperature of 28 to 30°C. Sporangia formation was induced on pepper seeds (3). Sporangia were ellipsoid, fusiform or obpyriform, papillate, occasionally bipapillate, caducous, with a long pedicel (up to 100 μm), and mean dimensions of 45 × 25 μm with a mean length/width ratio of 1.8. Chlamydospores ranged from 25 to 32 μm in diameter. Isolates were considered heterothallic because they did not produce gametangia in vitro or in planta. On the basis of morphological features, the isolates were identified as Phytophthora tropicalis Aragaki & Uchida. Identity was confirmed by sequence comparison in GenBank with 99% homology both for internal transcribed spacer (ITS) and mitochondrial partial COI for cytochrome oxidase subunit 1. The sequences of two isolates AB211 and AB212 were deposited in the European Nucleotide Archive (ENA) with accession nos. HF937577 and HF937578 for ITS, and HF937579 and HF937580 for COI, respectively. Pathogenicity tests were conducted in the greenhouse on a total of six 1-year-old shoots cut from R. catawbiense plants with two inoculation points each. Mycelial plugs cut from the margins of actively growing 8-day-old cultures on PDA were inserted through the epidermis to the phloem. Controls were treated as described above except for inoculation with sterile PDA plugs. Inoculated shoots were incubated in test tubes with sterile water for 1 week in the dark at 26 ± 2°C. Lesions were evident at the inoculation points. P. tropicalis was consistently reisolated from the margin of symptomatic tissues. Control shoots remained symptomless. In Italy, P. tropicalis has been reported on several ornamental species (1) and on apricot trees (4) indicating a broad host range. On the same host it has been reported in Virginia, United States (2). To the best of our knowledge, this is the first report of Phytophthora damage on Rhododendron caused by P. tropicalis in Italy. References: (1) S. O. Cacciola et al. Plant Dis. 90: 680, 2006. (2) C. X. Hong et al. Plant Dis. 90: 525, 2006. (3) E. Ilieva et al. Eur. J. Plant Path. 101: 623, 1995. (4) A. Pane et al. Plant Dis. 93: 844, 2009.

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Journal articles on the topic 'Gametangia'

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