Asexual Sporulation in the Oomycetes

Hardham, Adrienne R.; Hyde, Geoffrey J.

doi:10.1016/s0065-2296(08)60079-8

Cited by 50 publications

(36 citation statements)

References 120 publications

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“…6,10,25 For this reason, isolates of P. insidiosum have traditionally been identified as such on the basis of morphologic hyphal characteristics (broad, hyaline, rarely septate hyphae that are 4-10 m in diameter and branch at right angles), growth at 37 C, and production of motile biflagellate zoospores (asexual reproductive structures) in water cultures in association with plant material. 1,6,28,41 However, although the production of biflagellate zoospores is helpful in identifying isolates as oomycetes in the order Peronosporales, this characteristic is shared by other Pythium species 13,17 as well as by members of the genera Phytophthora 7 and Lagenidium 2,9 and thus is not specific for P. insidiosum. 1 Because of the difficulties associated with the identification of P. insidiosum based on morphologic features alone, supplemental techniques based on antigenic and molecular characteristics have been developed.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Microbial Culture Techniques for the Isolation of Pythium Insidiosum from Equine Tissues

et al. 2002

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Abstract. The purpose of this study was to evaluate the effects of sample handling, storage, and culture techniques on the isolation of Pythium insidiosum from infected equine tissues. Tissue and kunker samples obtained immediately posteuthanasia from a horse with subcutaneous pythiosis were used to assess the effects of sample type (kunkers vs. tissues), media type (selective vs. nonselective), storage technique, and storage time on P. insidiosum isolation rate. Overall, isolation rates were higher from fresh kunkers (94.6%) and stored kunkers (76.4%) than from fresh tissues (8.3%) or stored tissues (4.6%). Isolation of P. insidiosum also occurred more often on antibiotic-containing media than on nonselective media for both fresh and stored samples. For samples that were stored for 1-3 days prior to culture, P. insidiosum isolation rates were highest for the following techniques: kunkers stored at room temperature and plated on selective media (100%), kunkers stored at 4 C and then plated on either nonselective (91.7%) or selective (95.8%) media, kunkers stored on cold packs and then plated on either nonselective (93.8%) or selective (100%) media, kunkers stored in ampicillin solution and plated on selective media (100%), and kunkers stored in ampicillin/gentocin solution and plated on selective media (87.5%). For samples stored for 4-5 days, P. insidiosum isolation rates were highest for kunkers stored at 4 C and then plated on either nonselective (81.3%) or selective (87.5%) media, kunkers stored in ampicillin solution and then plated on selective media (87.5%), and kunkers stored in ampicillin/gentocin solution and plated on selective media (87.5%). Results of this study suggest that optimal isolation rates of P. insidiosum from infected equine tissues are achieved by culturing fresh kunkers on selective media. For samples that cannot be processed immediately, acceptable handling techniques include storage at room temperature for up to 3 days, refrigeration for up to 5 days, shipping on cold packs, and storage in antibiotic solution, each combined with subsequent inoculation on selective media.

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Section: Discussionmentioning

confidence: 99%

Evaluation of Microbial Culture Techniques for the Isolation of Pythium Insidiosum from Equine Tissues

et al. 2002

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“…An early suggestion that it could be a gel-like material that swells (De Bary, 1887, cited in Money and gained little support because such material was not visualized in living or chemically fixed cells although, more recently, electron-dense material which fills the extracellular space has been revealed in freeze-substituted sporangia of P. cinnamomi and P. palmivora (Hyde et al, 1991). Opinion has instead tended to favor the idea that the osmolyte is a soluble molecule , and possible candidate molecules include ␤-1,3-glucans (mycolaminarins) or glycoproteins of M r 60 -330 kDa released from cleavage vesicles (Hardham and Hyde, 1997). An alternative suggestion arises from the results reported in the present paper: is proline the extracellular osmolyte within the sporangium?…”

Section: Fig 7 (A) Concentrations Of Proline In Vegetative Hyphae (mentioning

confidence: 99%

The Role of Proline in Osmoregulation in Phytophthora nicotianae

Ambikapathy

Marshall

Hocart

et al. 2002

Fungal Genetics and Biology

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“…Sporangia accumulate many organelles absent from hyphae such as large peripheral vesicles, encystment vesicles, kinetosomes, and Xagella (Christen and Hohl 1972;Hardham and Hyde 1997). Several of the early-induced genes encode participants in vesicle movement that may aid in assembling these structures, such as -adaptin, clathrin-associated factors, and katanin p60 (Pi000624, Pi001002, Pi005726, Pi007620, Pi009985).…”

Section: Discussionmentioning

confidence: 99%

“…Most species must grow for several days before sporulation can initiate, indicating that "competence" as well as environmental inputs are required as in many true fungi (Axelrod et al 1973). However, there are fundamental cellular and molecular diVerences between oomycete and fungal spores (Hardham and Hyde 1997;Judelson and Blanco 2005). Oomycete hyphae are aseptate, with hyphal cytoplasm Xowing into sporangiophores and then sporangia without delimitation by specialized intermediary cells such as the foot cells or phialides of true fungi.…”

Section: Introductionmentioning

confidence: 99%

Gene expression changes during asexual sporulation by the late blight agent Phytophthora infestans occur in discrete temporal stages

et al. 2008

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Transcriptional changes during asexual sporangia formation by the late blight pathogen Phytophthora infestans were identified using microarrays representing 15,646 genes and RNA from sporulation time-courses, purified spores, and sporulation-defective strains. Results were confirmed by reverse transcription-polymerase chain reaction analyses of sporulation on artificial media and infected tomato. During sporulation, about 12% of genes were up-regulated compared to vegetative hyphae and 5% were down-regulated. The most prevalent induced genes had functions in signal transduction, flagella assembly, cellular organization, metabolism, and molecular or vesicular transport. Distinct patterns of expression were discerned based on the kinetics of mRNA induction and their persistence in sporangia. For example, most flagella-associated transcripts were induced very early in sporulation and maintained in sporangia, while many participants in metabolism or small molecule transport were also induced early but had low levels in sporangia. Data from this study are a resource for understanding sporogenesis, which is critical to the pathogenic success of P. infestans and other oomycetes.

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Asexual Sporulation in the Oomycetes

Cited by 50 publications

References 120 publications

Evaluation of Microbial Culture Techniques for the Isolation of Pythium Insidiosum from Equine Tissues

Evaluation of Microbial Culture Techniques for the Isolation of Pythium Insidiosum from Equine Tissues

The Role of Proline in Osmoregulation in Phytophthora nicotianae

Gene expression changes during asexual sporulation by the late blight agent Phytophthora infestans occur in discrete temporal stages

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