高光照引起烟草叶片衰老过程中过氧化氢的代谢与相关酶活性变化规律

High light accelerated tobacco leaf senescence:changes in H_2O_2 metabolism and enzyme activities

对高光照调控烟草叶片衰老过程中的过氧化氢代谢及相关酶活性进行研究,发现高光照(PFD 630μmol.m-2.s-1)相比正常光照(PFD 270μmol.m-2.s-1)加速了叶片衰老并伴随有较高的蛋白和叶绿素的降解率,同时过氧化氢的积累量增加。高光照导致过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性叶片在完全伸展前有明显的降低,同时却引起超氧化物歧化酶(SOD)活性升高。烟草叶片的过氧化物酶(POD)活性在高光照情况下持续升高到最老的叶片才开始下降。上述结果表明,在高光照加速的烟草叶片衰老过程中,当叶片完全伸展后,叶片的过氧化氢的代谢受到CAT、APX和SOD活性变化的共同影响。

The possible role of H202 metabolism in high light-regulated senescence of tobacco （Nicotiana rustica L. , Gansu yellow flower） leaves was investigated. High light （PFD 630 μmol·m^-2, s^-l） accelerated leaf se- nescence with higher protein and chlorophyll decrease rates but at the same time caused more H202 accumulation than that of normal light （PFD 270 μmol·m^-2. s^-l）. High light treatment resulted in distinct lower catalase and a- scorbate peroxidase activities and higher superoxide dismutase activities than that of normal light after leaf reached full expansion. Leaf peroxidase activities kept rising under high light until the oldest leaf. The results obtained sug- gest that the accelerated leaf senescence by high light is closely related to the changed H2 02 metabolism by catalase and ascorbate peroxidase and superoxide dismutase after leaf reached full expansion.