Induction of defense genes in Brassicajuncea against Alternaria brassicae

摘要

Brassica juncea is the second most important oil crop in India, next to groundnut only. But unfortunately, up to 35-42% yield losses are reported each year because of fungal disease caused by Alternaria brassicae. The absence of sources of resistance against this pathogen among sexually compatible relatives emphasizes the need of adopting biotechnological strategies to improve the resistance ofB. juncea. Therefore our project is aimed at isolating and characterizing important defense-associated genes in this species and study their regulation in order to generate fungus-resistant Brassica. Here, we report on the differential regulation of different antifungal genes, namely, PR1, PR2 (glucanase), PR3 (chitinase), PR4, PR5 and defensin by distinct signaling pathways that are mediated by salicylic acid (SA) or jasmonic acid (JA) in B. juncea. We shall also present our work in producing defense-induced cDNA libraries in B. juncea and the isolation of above mentioned defense genes and their characterization. In addition, we have also isolated a regulatory defense gene NPR1 which is an activator of transcriptional factors.Its characterization and relevance will be discussed. We have also isolated a gene coding a protein that interacts with the R-gene product. This gene product probably plays significant roles in the infection signal transduction pathway(s).