Analysis of the host hormonal signaling involved in Brassica napus - Leptosphaeria maculans pathosystem
C. YANG (1), D. Fernando (1) (1) Department of Plant Science, University of Manitoba, Canada

Canola (Brassica napus cv.) is the number one oilseed crop in Canada. Blackleg, caused by Leptosphaeria maculans, is the most economically important disease of canola which may wipe up to 90% of yield in one growing season. Evidence from previous studies has shown that plant is able to adjust its internal hormone secretion and signaling to defend itself against different types of pathogens and invaders. The objective of this study is to understand the regulation of hormonal signals in quantities and timing patterns in Brassica napus-Leptosphaeria maculans pathosystem. The isolates HCRT75 8-1 (AvrLm4-7 and AvrLm6) and HCRT77 7-2 (AvrLm1, AvrLm4-7 and AvrLm6) were chosen to inoculate on the selected canola cultivars which are Westar (no Rlm genes), Surpass400 (LepR3 and RlmS) and 01-23-2-1 (Rlm7). The inoculations obtained three disease severities (susceptible, intermediate and resistant). Several genes related to salicylic acid and ethylene biosynthesis (e.g. ICS1, ACO1) and signals (e.g. WRKY70, PR1, PR4) were found to be essential to achieve intermediate and resistant phenotypes. The timing patterns of those SA and ET related genes suggested that those signals are active during the biotrophic phase of blackleg. The current qPCR results suggested that the trade-offs of hormonal signaling are different depending on the level of severity. This study helps to extrapolate which type of allocation among hormonal signals in B. napus is most effective to resist to L. maculans.

Abstract Number: P16-482
Session Type: Poster