Reduction of Rubisco amount by UV-B radiation is related to increased H2O2 content in leaves of mung bean seedlings.
To understand the role of H(2)O(2) in the damaging effect of UV-B radiation on ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) content, the time courses of changes in Rubisco and H(2)O(2) contents under UV-B treatment were measured in the primary leaves of two mung bean cultivars (Phaseolus raditus L. cv. Zhonglv-1 and Qindou-20). A 0.4 W/m(2) UV-B treatment caused a drop of the former to about 1/3 and a 30%-40% rise in H(2)O(2) content in a week in both cultivars but with Qindou-20 showing stronger responses. Such higher rate of increase in proteolytic activity under UV-B treatment implies that UV-B lowers Rubisco by activating proteolytic enzymes which hydrolizes Rubisco. Scavenging of H(2)O(2) by exogenously added ascorbic acid (AsA) significantly inhibited the UV-B-induced decrease in Rubisco amount and increases in H(2)O(2) level and proteolytic activity. It is shown that H(2)O(2) participates in the UV-B-induced reduction of Rubisco amount. It is suggested that H(2)O(2) stimulates the degradation of Rubisco by activation of proteolytic systems.
He
Jun-Min
JM
Center of Bioinformation, School of Life Sciences and Technology, Xi'an Jiaotong University, Xi'an 710049, China. hejunmin1965@163.com
She
Xiao-Ping
XP
Meng
Zhao-Ni
ZN
Zhao
Wen-Ming
WM
D001205:Ascorbic Acid / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000032:analysis*; D027805:Phaseolus / Q000737:chemistry / Q000528:radiation effects*; D018515:Plant Leaves / Q000737:chemistry*; D012273:Ribulose-Bisphosphate Carboxylase / Q000032:analysis*; D036226:Seedlings / Q000737:chemistry*; D014466:Ultraviolet Rays
D006861:Hydrogen Peroxide; D012273:Ribulose-Bisphosphate Carboxylase; D001205:Ascorbic Acid