Introgression of osmotin gene for creation of resistance against Alternaira blight by perturbation of cell cycle machinery

Abstract

Pathogenesis related protein, osmotin, when introgressed into Brassica juncea plants, provided tolerance to fungal attack. Osmotin is thought to influence the signal transduction pathway. Possible influence of osmotin gene transfer on the cell cycle and cell death pathways was investigated using transformed B. juncea calli as model system. It was observed that partially purified Alternaria toxin inhibited the growth of non-transformed calli; whereas, transformed calli resisted the effect of toxin, which appears to counteract the inhibitory effects of phytotoxins. The toxin also initiates the programmed cell death (PCD) in the calli. The toxin increased the expression of P 53 and caspase-like proteins in the non-transformed calli and suppressed the expression of cyclin B and CDC proteins. It was further supported by the fragmentation of DNA in response to toxin treatment. However, the transformed calli, when challenged with toxin, suppressed the expression of P 53 , while caspase 1 was not affected. On the basis these results, it can be concluded that osmotin tampers the P 53 -mediated PCD