Effects of enhanced UV-B radiation on protein metabolism of bean leaves

Bean ( Phaseolus vulgaris L.) seedlings were groan in a greenhouse condition under UV-B (280 similar to 320 nm) radiation and an W-B-free control condition. At early stage of bean growth, UV-B radiation(UV-B-BE:16 kJ . m(2) . d(-1)) increased the synthetic rate of protein in bean leaves. UV-B radiation decreased the synthetic rate of protein and the content of soluble protein, increased the activities of caseolytic enzymes and the content of total amino acids in bean leaves at later growth stage. The results of SDS-PAGE indicated that UV-B radiation increased the contents of polypeptide in a range of 99 kD,88 kD,76 kD,42 kD,35 kD and 33 kD at the early stage, and increased that of 10 similar to 14 kD,29 kD,33 kD and 35 kD at later growth stage. It is suggested that the increase of these polypeptides is an adaptation response of plants to the enhanced UV-B radiation.