Altered protein synthesis during in situ oat leaf senescence

Quantitative and qualitative changes in protein synthesis during in situ senescence of oat ( Avena saliva L. cv. Victory) leaf have been examined. The rate of protein synthesis shows a transitory increase during early stages of senescence. This increase is not accompanied by a corresponding increase in amino acid uptake and is smaller when expressed on a dry weight rather than a protein basis. Total protein, total RNA and poly(A)⁺-RNA decline rapidly during senescence. Analysis of protein populations with 2-D SDS-PAGE shows that while some proteins decline sharply during leaf senescence, the synthesis of several others is induced or enhanced. Synthesis of new proteins shown in this study may explain the reported requriement for protein synthesis in leaf senescence.