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TECHNICAL SESSION: Fungal and oomycete pathogens: New approaches to disease resistance

Cold Shock – Uncovering transcriptional changes driving a model for stress-related disease resistance
Bill Weldon - Cornell University. David Gadoury- Cornell University, Michael Osier- Rochester Institute of Technology, Alisson Kovaleski- USDA-GGRU, Cal Palumbo- Rochester Institute of Technology, Lance Cadle-Davidson- USDA Grape Genetics Research Unit

Acute cold Stress-Induced Disease Resistance (SIDR) was first described in the grape powdery mildew (Erysiphe necator) pathosystem, and later in powdery mildews of hop and arabidopsis. Exposure of Vitis vinifera to brief cold events (e.g. 4hrs at 4C) induced a transient, quantitative increase in host resistance that peaked 24 hours after the cold event and dissipated within 48 hours. We paired this time course phenotyping of E. necator inoculated leaf discs with 3’ RNA sequencing to investigate transcriptional changes driving the transient cold SIDR response on V. vinifera ‘Chardonnay’. Through k-means clustering, pathways analysis in VitisPathways, and molecular network visualization using VitisNet 12X, the data most strongly supported a transient down-regulation of photosynthetic activity as the transcriptional driver of the cold SIDR response. Pathways associated with photosynthesis, including electron transport and antennae proteins were highly down-regulated. Moreover, gene precursors to proteins of photosystem I and II were down-regulated at the peak resistance point, 24hrs after cold exposure, as were most gene precursors to light harvesting complexes I and II. Cold SIDR has been shown to cause stalling of powdery mildew epidemics in both grapevine and hops. Thus, these results provide gene targets in cold SIDR associated transcriptional pathways that could affect disease management in diverse powdery mildew pathosystems.