烟草叶片发育过程中光合功能衰退与H2O2积累的关系

以烟草（Nicotiana tabacum L．cv NC89）为材料，研究了叶片发育过程中H2O2积累与叶绿体光合功能衰退、抗坏血酸-谷胱甘肽（AsA—GSH）循环的关联。结果表明，光合功能衰退过程中，各光合参数均表现为先缓慢后快速的下降趋势，核酮糖-1，5-二磷酸羧化酶（RuBPCase）活性下降较电子传递活性下降迅速，H2O2含量与叶绿素含量、光合速率、RuBPCase活性、抗坏血酸过氧化物酶（APX）、谷胱甘肽还原酶（GR）活性显著负相关。H2O2的定位染色也证实光合功能衰退与H2O2积累密切相关。APX和GR在光合功能可逆衰退阶段维持较高水平，不可逆衰退阶段下降稍快。烟草叶片光合功能衰退快于AsA—GSH循环运转的下调。

RELATION BETWEEN THE DECLINE OF PHOTOSYNTHETIC FUNCTION AND H2O2 ACCUMULATION IN LEAF LIFE SPAN OF TOBACCO

Correlations among H2O2 accumulation, chloroplast photosynthetic function decline and H2O2-scavenging enzymes of AsA-GSH cycle in leaf life span of tobacco (Nicotiana tabacum L. cv NC89) were studied. Photosynthetic rate displayed elevated phase,active photosynthesis duration and sharp fall phase while the chlorophyll content displayed elevated phase,relative steady phase and sharp fall phase during leaf life span. The decline of photosynthetic parameters was slow first and then sharp,and the decline of ribulose 1,5-bisphosphate carboxylase (RuBPCase) activity was obviously faster than that of photosynthetic electron transport activity during the decline of photosynthetic function. The decline of photosynthetic function was divided into reversible decline and irreversible decline. Ascorbate peroxidase (APX) and Glutathione reductase (GR) remained higher level in reversible decline stage,while declined fast in irreversible decline stage. H2O2 content was significantly negative correlated with chlorophyll content, photosynthetic rate, RuBPCase activity,APX and GR activity during the decline of photosynthetic function in tobacco leaves. Localized staining of H2O2 stated that the decline of photosynthetic function was closely correlative with H2O2 accumulation. The decline of photosynthetic function in tobacco leaves was faster than the decline of AsA-GSH cycle function.