Submitted to: Biennial Conference on Molecular and Cellular Biology of the Soybean
Publication Type: Abstract Only
Publication Acceptance Date: July 20, 2010
Publication Date: August 8, 2010
Citation: Upchurch, R.G., Ramirez, M.E. 2010. Pathogen growth in soybean seeds: relationships with fatty acid composition and defense gene expression. Biennial Conference on Molecular and Cellular Biology of the Soybean, August 8-11, 2010. Technical Abstract: Temperature during seed development strongly modulates the oleate: linoleate content (O: L) in seeds of the soybean line N0304-303-3. We found that increased oleate in seeds grown at warmer temperatures was associated with higher expression of the stearoyl acyl carrier protein desaturase alleles GmSACPD-A/B in addition to the previously reported thermally induced decrease in enzymatic activity of the omega-6 desaturases GmFAD2-1A and 2-1B. We used temperature manipulation to produce seeds with differing O: L in order to examine the effect of seed fatty acid content on the growth of the fungal pathogens Cercospora kikuchii and Diaporthe phaseolorum var. meridionalis using inoculated detached seeds. Seeds with higher oleate were found to support increased growth of C. kikuchii, while seeds with higher linoleate supported increased growth of D. phaseolorum. Gene expression analysis showed that seeds produced at either a warm or a cool relative to normal temperature had, prior to inoculation, down-regulated pathogenesis-related PR1, PR3, PR4, and PR10 gene expression. Taken together, our data suggests that the oleate: linoleate content and defense gene expression (if synonymous with protein expression) are likely key factors controlling the initial growth of these pathogens in inoculated immature soybean seeds.