过氧化氢参与烟草叶片衰老调节的研究（简报）

叶片衰老是一个复杂的过程．多年来人们对叶片衰老的机制开展了大量的研究。许多研究证明叶片中H2O2的迅速积累与叶片的衰老密切相关^1-3]，然而，H2O2的积累是衰老的结果还是作为信号启动衰老？H2O2作为植物细胞的信号分子，调控一系列重要的生理生化过程，如系统获得抗性（SAR）、细胞衰老与程序化死亡（PCD）、气孔关闭、根的生长、细胞壁的发育等^4]。H2O2参与脱落酸（A—BA）、甲基茉莉酸（MJ）诱导的水稻叶片衰老，且H2O2产生早于叶片衰老^2,5]。

HYDROGEN PEROXIDE IS INVOLVED IN REGULATION OF TOBACCO LEAF SENESCENCE

Effects of various exogenous hydrogen peroxide （H2O2） concentrations on leaf senescence of tobacco （Nicotiana tabacum L. ） were studied. The results showed that 0.1 and 1 mmol/L H2O2 had little effects on the leaf senescence of tobacco, the contents of chlorophyll and soluble protein were decreased in varying degrees by 10, 100 mmol/L H2O2 treatment, the decreased chlorophyll and soluble protein contents were significantly correlated with increased endogenous H2O2 content. SDS-PAGE of soluble protein and localized staining of H2O2 showed consistency with respective content. Chloroplast ultrastructure were observed in the mesophyll cells of tobacco and there was a little change by 10 mmol/L H2O2 treatment, and a remarkable breakdown of granal stacks and disorganized thylakoid membranes were revealed by 100, 200 mmol/L H2O2 treatment. RT-PCR analysis showed the expression level of senescence associated genes SAG12 was low by 10mmol/L H2O2 treatment and increased by 100 mmol/L H2O2 treatment. These results strongly suggested the tobacco leaf senescence was induced by 10 mmol/L H2O2 and accelerated the progression by high concentration （100, 200 mmol/L） H2O2 stress.