Studies on the sterility mosaic disease of pigeon pea. III. Nitrogen metabolism of infected plants

Abstract

A decrease in the chloroplastic protein and a slight increase in the cytoplasmic protein were seen in the diseased leaves. There was no appreciable quantitative difference in the amino-acid contents of proteins of healthy and diseased plants. The total nitrogen content of diseased leaves showed a progressive increase over healthy during the day starting from the morning till evening. The free amino-acids of diseased leaves showed variations both in quality and quantity. Alanine, asparagine, arginine and aspartic acid were found to be in higher concentrations in diseased leaves, the increase being proportional to the severity of disease symptoms. The presence of two unidentified amino-acids was detected only in diseased leaves. The amino-acids, alanine, asparagine, aspartic acid and arginine which were in very high concentrations in diseased leaves at 6 a.m. were observed to be either completely absent or present only in very small amounts at 6 p.m. A decrease in the C/N ratio resulted due to virus infection. This reduction could be attributed to the reduction in the carbohydrate content and increase in nitrogen content of diseased leaves.