B. napus-Leptosphaeria maculans interaction: Perception and downstream signalling
H. BORHAN (1), P. Haddadi (2), L. Ma (2) (1) AAFC, Canada; (2) Agriculture and Agri-Food Canada, Saskatoon Research and Development Centre, Canada

Blackleg, caused by the ascomycete fungus Leptosphaeria maculans (Lm), is a common disease in most canola/ rapeseed (Brassica napus) producing countries. After germination of L. maculans spores on cotyledons and leaves of young seedlings, hyphae enter and grow between the mesophyll cells. In the absence of race specific resistance (R) genes, the pathogen continues to grow causing tissue collapse and the development of lesions on cotyledons, leaves and at the base of the stem. Our recent report on isolation of two B. napus R genes, LepR3 and Rlm2, both encoding receptor like proteins (RLPs), revealed the role of cell surface receptors in recognition of Lm for the first time. LepR3 and Rlm2-mediated recognition of their corresponding Lm effectors, AvrLm1 and AvrLm2 respectively, requires SOBIR1 and BAK1 receptor like kinases (RLK). Extensive RNA-seq analysis of infected cotyledon, petiole and stem tissues has provided insight into the spatiotemporal gene regulation of both the host and pathogen as well as the biotrophy/necrotrophy life stages of Lm. In addition, genotype- and R gene-specific defence response against Lm was studied by conducting deep RNA-seq on B. napus introgression lines containing single race-specific R genes in a common susceptible background. Gene expression dynamics revealed the molecular patterns underlying variation in defense response pathways of different R genes and the interplay between PTI and ETI.

Abstract Number: P11-345
Session Type: Poster