Elicitation of defense related enzymes and resistance by L-methionine in pearl millet against downy mildew disease caused by Sclerospora graminicola

Abstract

Induction of resistance to downy mildew in pearl millet was studied after treatment with L-methionine. The disease severity was drastically reduced in the seedlings after treatment with L-methionine. Northern hybridization was used to study the transcript (mRNA) accumulation of defense response genes upon treatment with L-methionine in pearl millet seedlings and the mechanism during the induction of resistance. The gene activation patterns in the highly resistant cultivar IP18294 were compared with those exhibited by the susceptible cultivar 7042S at various time intervals to determine if differences in timing or levels of transcript accumulation could be correlated with the differences in the susceptibility of pearl millet to the downy mildew pathogen, Sclerospora graminicola. The mRNA levels of genes for Pr-1a, β-1,3-glucanase, chitinase, peroxidase, lipoxygenases and chalcone synthase showed an increase after inoculation with S. graminicola. Significant gene activation was observed in the susceptible cultivar 7042S after treatment with L-methionine followed by challenge inoculation with the downy mildew pathogen which was comparable to the resistant cultivar.