Interactions among severity of spot blotch disease of wheat caused by Bipolaris sorokiniana, nitrogen supply and WRKY transcription factor functions
Saddam Baba: Newcastle University
<div>Spot blotch caused by <em>Bipolaris sorokiniana</em> is a serious disease of wheat grown in warm climates. WRKY transcription factors (WRKYTFs) have been reported to be involved in plant responses to pathogens and to nutrient stress. We have found that in wheat, nutrient stress affects spot blotch severity, and nutrient stress and infection cause interacting changes in WRKYTF gene expression<em>.</em> Here we report on time dependence of pathogen development and WRKYTF gene expression in leaves of two Iraqi wheat cultivars, Rasheed (more susceptible to spot blotch) and Latifia (more resistant), and on pathogen development in wheat TILLING lines in which the WRKYGQK sequence characteristic of WKRYTFs is mutated. Seedlings of the two Iraqi wheats were supplied with 7.5 mM nitrogen and TILLING lines with 0.75 mM, 3.75 mM or 7.5 mM nitrogen. Fourteen-day-old seedlings were inoculated with <em>B. sorokiniana</em>. Pathogen development was assessed by binding of FITC-conjugated wheat germ agglutinin and RT-qPCR. The two methods gave consistent results. Fungal growth decreased as nitrogen input was reduced. Expression of different WRKYTF genes increased over time in Latifia, but decreased in Rasheed at 96 h after infection. Fungal growth was altered in TILLING lines. In one line there was higher fungal growth when N supply was reduced, the opposite pattern to wild-type plants. The results demonstrate that wheat WKRYTFs influence pathogen development and its interaction with nitrogen supply.</div>
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