Studies on peanut green mosaic virus infected peanut ( Arachis hypogaea L.) leaves. II. Chlorophyll-protein complexes and polypeptide composition of thylakoid membranes

Abstract

The chlorophyll-protein complexes and the polypeptides of the chloroplast thylakoid membranes from healthy and peanut green mosaic virus infected peanut leaves were examined. CPa, the chlorophyll-protein complex associated with the reaction centre of photosystem II, was markedly reduced in severely infected leaves and this reduction was accompanied by reductions in the light harvesting chlorophyll-protein complexes. The P 700 chlorophyll a-protein complex of photosystem I increased in infected leaves. Polypeptide analysis of the thylakoid membranes from healthy and infected leaves showed a significant reduction in the 47 kD polypeptide in severely infected leaves. The α- and β-subunits of the chloroplast coupling factor and the 23 kD polypeptide were marginally reduced while the 11, 16, 17 and 44 kD polypeptides increased in severely infected leaves. There was a correlation between the reduction in the amount of the 47 kD polypeptide and photosystem II activity in virus infected leaves. The results support the finding that decreased photosynthesis in infected tissue is in part due to decreased levels of chlorophyll a.