Transcriptome analysis of the snow rot pathogen Pythium iwayamai
J. R. IBARRA CABALLERO (1), N. Tisserat (1). (1) Colorado State University, Fort Collins, CO, U.S.A.
<i>Pythium iwayamai</i> is a psychrophilic pathogen of turfgrasses and small grains. The mechanism by which this oomycete survives and infects plants under snow cover has not been studied in detail. We isolated RNA from <i>P. iwayamai</i> grown at 7 C and 19 C and in the presence and absence of ‘Penncross’ creeping bentgrass. RNA-seq was used to assemble and compare the transcriptomes under the various treatment combinations. These transcriptomes were also compared to those of the non-psychrophilic <i>P. irregulare</i> grown under the same conditions. <i>P. iwayamai</i> differentially expressed some proteins, including proteases and abc transporters at the lower temperature and in the presence of bentgrass. The proteases were not expressed at low temperatures in the absence of the bentgrass. Few glucosidases were differentially expressed and no antifreeze proteins were detected. Transcriptomes of <i>P. irregulare</i> differed from those of <i>P. iwayamai</i> at both temperatures, with more proteases and glucosidases differentialy expressed at the higher temperature. Results suggest that increased protease activity may be an important component of the infection process of <i>P. iwayamai</i> at low temperatures and <i>P. irregulare</i> at higher temperatures.
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