ULTRAVIOLET-B (280-320 NM) ENHANCED RADIATION-INDUCED CHANGES IN CHLOROPHYLL-PROTEIN COMPLEXES AND POLYPEPTIDE COMPOSITION OF CHLOROPLASTS IN VIGNA-UNGUICULATA SEEDLINGS GROWN AT VARIOUS TEMPERATURES

The changes in pigment-protein composition of chloroplasts in Vigna un guiculata (L.) Walp seedlings grown under control and ultraviolet-B (U V-B) enhanced radiation at various temperatures were studied. The chlo rophyll-protein (CP) complexes isolated from seedlings after 60 h of c ontinuous UV-B enhanced radiation treatment showed temperature-depende nt changes in their levels. At 10 degrees C, well marked CP1, CP2a, CP 47, CP2 and free pigment bands were seen in UV-B treated seedlings whi le control seedlings had no detectable green bands. UV-B enhanced radi ation decreased the level of CP1, CP2a and CP2 complexes which was mor e pronounced at 20 and 30 degrees C than at 40 degrees C. The analysis of chloroplast polypeptides revealed a drastic decrease in the levels of 55, 47, 33, 25, 23, 22 and 17 kDa polypeptides in UV-B treated see dlings at 20 and 30 degrees C, and marginal decrease in the levels of 47, 43 and 16 kDa polypeptides at 40 degrees C. In contrast to this, a t 10 degrees C large increase in many polypeptides was noticed in UV-B treated seedlings.