Varietal differences in continuous light-induced chlorosis and antioxidative enzymatic activities in Cucurbita
2002
"Murakami, K. (Okayama Univ. (Japan). Faculty of Agriculture) | Orita, H. | Masuda, M. "
"The varietal differences in response to continuous light exposure of Cucurbita plants were investigated in relation to antioxidative enzvmatic activity. In cultivars of C. moschata except 'Butternut', chlorosis did not occur. and plants grew vigorously even at 24/0 hr. Chlorosis developed at the 3-leaf stage in C. moschata 'Butternut' and the two cultivars of C. maxima at 24/0 hr. Activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase in the 3rd true leaf were determined in 'Butternut' (C. moschata sensitive to continuous light) and 'Hyuga No.14' (C. moschata to continuous light) at the 3rd leaf stage. In 'Butternut', the activities of SOD and APX at 24/0 hr were 4-and 2-fold higher than those at 12/12 hr, respectively, whereas catalase activity was slightly higher at 24/0 hr. The hydrogen peroxide content in leaves was also higher at 24/0 hr. In 'Hyuga No.14', no differences were noted between the two photoperiodic treatments in these antioxidative enzymatic activities and hydrogen peroxide content. These results indicate that continuous-light induced oxidative stress is associated with leaf injury in 'Butternut'.
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