A novel approach to detect fungal and wheat genes involved in leaf rust disease by expression associations during various race-specific interactions
G. BAKKEREN (1), H. Khalil (1), X. Wang (2), R. Linning (1), D. Joly (3), D. Cram (4), N. Thiessen (5), G. Taylor (5), B. McCallum (2), B. Saville (6) (1) Agriculture & Agri-Food Canada, Summerland Research & Development Centre, Canada; (2) Agriculture & Agri-Food Canada, Morden Research & Development Centre, Canada; (3) Department of Biology, Université de Moncton, Canada; (4) National Research Council Canada, Canada; (5) Genome Sciences Centre, Canada; (6) Trent University, Canada

Often, NGS transcriptome analyses focus on either hosts or pathogens. Here we compared global gene expression dynamics of both wheat leaf rust fungus Puccinia triticina (Pt) and wheat Triticum aestivum (Ta) host genes during four genetically defined interactions. Four Pt races, BBBD (representing the race 1 reference genome sequence), MBDS, SBDG and FBDJ, were inoculated on susceptible cv. Thatcher and two near-isogenic lines carrying the leaf rust resistance genes Lr2a and Lr3, representing various infection types (ITs): highly susceptible (IT3 or 4), intermediate resistant (IT2), and highly resistant triggering necrosis (IT1). Sampling of all interactions allowed association of ITs with gene expression by Illumina-based RNAseq. Relative expression levels of both Pt and Ta genes were calculated using the BBBD reference genome and the draft Ta genome (IWGSC). In-depth analysis of Pt candidate effector protein genes revealed sequential waves of their expression across time. Focusing on highly expressed effectors, we identified Pt genes whose expression varied significantly among various ITs. By correlating these expression patterns with those of the host, we detected wheat genes likely affected by and hence possible interacting with those effectors. Fluorescent chimers of five Pt effectors, whose transcript levels were highly associated with wheat transcripts across various interactions, were targeted to different plant organelles in a heterologous N. benthamiana system.

Abstract Number: P11-344
Session Type: Poster