Innate immunity in a forest tree: RLP-RLK complex mediates resistance to Septoria stem canker in Populus trichocarpa
J. LEBOLDUS (1), W. Muchero (2), J. Chen (2), J. Chang (3), A. Weisberg (3), K. Dunnell (3), G. Tuskan (2), R. Brueggeman (4) (1) Oregon State University, U.S.A.; (2) Oak Ridge National Laboratory, U.S.A.; (3) Oregon State University, U.S.A.; (4) North Dakota State University, U.S.A.

Populus species and their hybrids are ecologically important in riparian ecosystems and have tremendous potential as a biofuel feedstock. Populus plantations are severely affected by the fungal pathogen that causes Septoria stem canker. A genome-wide association mapping studied was done using 1,081 unrelated P. trichocarpa genotypes sampled across the species range. Each individual was tested in replicated greenhouse experiments for their canker severity in response to S. musiva . Associations between the phenotype and 8.2 million single nucleotide polymorphisms were assessed using the EMMAX package. Notably, the two top associations involved predicted pattern recognition receptors, two paralogous leucine-rich receptor-like proteins (RLPs) [P =1.56E-38; P =2.78E-14]. A SnpEff analysis revealed high-impact mutations in the RLPs, potentially resulting in loss-of-function leading to susceptibility. The third most significant associations involved an L-type lectin receptor-like kinase (L-RLK) [P = 2.15E-16]. The differences in expressions of these genes between a resistant and susceptible genotype were also analyzed across a 0-, 24- and 72-hour time-course experiment. In the resistant genotype the two RLPs and the L-RLK exhibited major transcriptional changes with expression peaking at the 24-hour time-point. These data are consistent with the hypothesis that resistance to Septoria stem canker in P. trichocarpa is mediated by an RLP-RLK complex.

Abstract Number: P17-554
Session Type: Poster