Increased Proteins in Diseased Leaves of Rice Plants in the Early Stage of Infection by Helminthosporium oryzae

Abstract

In the present paper, some biochemical characteristics of the protein fractions of which increased in leaves inoculated with Helminthosporium oryzae are discussed.
1. Neither spore germination nor the elongation of germ tubes was inhibited by the protein fraction increased in the inoculated leaves.
2. Catalase activity was increased markedly in the protein fraction eluted with 1.0M tris buffer (pH 7.2), while no β-amylase activity was detected in the protein fraction.
Unexpectedly the protein fraction inhibited β-amylase activity.
The β-amylase inhibition by the proteins was discussed in relation to the mechanism of starch accumulation which was found usually in the surrounding area of diseased spot.
3. The amino acid contents of protein fraction eluted with 0.5M tris buffer (pH 7.2) were analysed by using amino acid auto-analyser. The protein fraction obtained from diseased leaves contained more aspartic acid and less glutamic acid than that from healthy leaves.