Genetic architecture underlying response to the fungal pathogenDothistroma septosporumin lodgepole pine, jack pine, and their hybrids

Abstract

AbstractIn recent decades,Dothistromaneedle blight (DNB), a pine tree disease caused by the fungal pathogenDothistroma septosporum, has severely damaged lodgepole pine (Pinus contortaDougl. ex Loud. var.latifolia) in British Columbia, Canada. The pathogen has already shown signs of host shift eastward to lodgepole × jack hybrid pine populations, and possibly into pure jack pine (Pinus banksianaLamb.). However, we have little knowledge about mechanisms of resistance toD. septosporum, especially the underlying genetic basis in pines. In this study, we conducted controlled inoculations to induce infection byD. septosporumand performed a genome-wide case-control association study with pooled sequencing (pool-seq) data to dissect the genetic architecture underlying response in lodgepole pine, jack pine, and their hybrids. We identified candidate genes associated withD. septosporumresponse in lodgepole pine and in lodgepole × jack hybrid pine populations. We also assessed genetic structure in hybrid populations and inferred that introgression may affect the distribution of genetic variation involved inD. septosporumresponse in the study populations. These results can be used to develop genomic tools to evaluate DNB risk, guide forest management strategies, and potentially select for resistant genotypes.