Alternaria brassicae interactions with the model Brassicaceae member Arabidopsis thaliana closely resembles those with Mustard (Brassica juncea)

Alternaria leaf blight, a disease of oilseed Brassicas is caused by a necrotrophic phytopathogenic fungus Alternaria brassicae. The details of its pathogenesis and defence responses elicited in the host upon infection have not been thoroughly investigated. Here, Arabidopsis accession Gre-0 was identified to be highly susceptible to A. brassicae. A comparative histopathological analysis for disease progression and plant responses to A. brassicae in Arabidopsis and Brassica juncea revealed significant similarities between the two compatible pathosystems. Interestingly, in both the compatible hosts, ROS accumulation, cell death and callose deposition correlated with the development of the disease. Based on our results we propose that Arabidopsis-Alternaria brassicae can be an apt model pathosystem since it emulates the dynamics of the pathogen interaction with its natural host- Brassicas. The existing genetic diversity in Arabidopsis can be a starting point to screen for variation in responses to Alternaria leaf blight. Furthermore, several tools available for Arabidopsis can facilitate the dissection of genetic and molecular basis of resistance.