The Resistance of Narrow-Leafed Lupin to Is Based on the Rapid Activation of Defense Response Genes.

Narrow-leafed lupin ( L.) is a grain legume crop that is advantageous in animal nutrition due to its high protein content; however, livestock grazing on stubble may develop a lupinosis disease that is related to toxins produced by a pathogenic fungus, . Two major unlinked alleles, and , confer resistance to this fungus. Besides the introduction of these alleles into modern cultivars, the molecular mechanisms underlying resistance remained unsolved. In this study, resistant and susceptible lines were subjected to differential gene expression profiling in response to inoculation, spanning the progress of the infection from the early to latent phases. High-throughput sequencing of stem transcriptome and PCR quantification of selected genes were performed. Gene Ontology term analysis revealed that an early (24 h) response in the resistant germplasm encompassed activation of genes controlling reactive oxygen species and oxylipin biosynthesis, whereas in the susceptible germplasm, it comprised induction of xyloglucan endotransglucosylases/hydrolases. During the first five days of the infection, the number of genes with significantly altered expressions was about 2.6 times higher in resistant lines than in the susceptible line. Global transcriptome reprogramming involving the activation of defense response genes occurred in lines conferring and resistance alleles about 4-8 days earlier than in the susceptible germplasm.