Morpho-Pathological and Global Transcriptomic Analysis Reveals the Robust Nonhost Resistance Responses in Chickpea Interaction with .

Alternaria blight, caused by , causes considerable yield loss in crops. While several blight-resistant varieties have been developed using resistance sources from host germplasm, none of them are entirely successful in imparting durable resistance. This has prompted the exploration of novel gene pools of nonhost plant species. Nonhost resistance (NHR) is a durable form of resistance, comprising pre- and postinvasion layers of defense. We aimed to identify the molecular basis of NHR to and identify the layers of NHR operating in a nonhost, chickpea (). To elucidate the layers of NHR operating against , we compared the histopathology and infection patterns of in and . Delayed conidial germination, impeded hyphal growth, suppressed appressorium formation, and limited hyphal penetration occurred in the nonhost plant compared with the host plant, implying the involvement of the preinvasion layer of NHR in Next, we investigated the molecular basis of robust NHR, in challenged with , by microarray-based global transcriptome profiling. Genes involved in stomatal closure, cuticular wax biosynthesis, cell-wall modification, and secondary metabolite production (contributing to preinvasion NHR) as well as reactive oxygen species (ROS) and cell death (contributing to postinvasion NHR) were found to be upregulated. Consistent with transcriptomic analysis, the morpho-pathological analysis revealed stomatal closure, ROS accumulation, and localized cell death in as the defense strategies against Thus, we identified NHR-contributing genes with potential applications in blight resistance gene transfer to .