Induced expression of oryzain α gene encoding a cysteine proteinase under stress conditions

Oryzain alpha-A, a cysteine proteinase gene was cloned from rice (Oryza sativa L. cv. Aichi-asahi) leaves infected with Magnaporthe grisea. The protein sequence deduced for oryzain alpha-A shares high identity with that of oryzain alpha, a gene expressed in germinating rice seed. Oryzain alpha-A gene expression was induced by the blast fungus, Magnaporthe grisea, and the transcript level was even higher in the compatible interaction with rice than in the incompatible interaction. Expression of oryzain alpha-A was also inducible by wounding, ultraviolet radiation, and treatment with salicylic acid and abscisic acid, with no expression induced by methyl jasmonate. The function of oryzain alpha-A in cell death in rice is discussed.