水杨酸和草酸对光氧化胁迫下黄瓜叶片光合机构及叶黄素循环的影响

 以500μmol·L - 1的甲基紫精(MV) 溶液涂抹叶片, 研究了光氧化胁迫条件下外源水杨酸(SA) 和草酸(OA) 对黄瓜叶片光合作用、叶绿素荧光参数和叶黄素循环的影响。结果表明, 在胁迫前2 d分别用SA 012 mmol·L - 1和OA 5 mmol·L - 1处理叶片, 减小了光氧化胁迫下净光合速率( Pn) 、蒸腾速率(Tr) 、PSⅡ光合电子传递量子效率(ΦPSⅡ)、叶绿素光化学猝灭系数( qP) 的下降及胞间CO2 浓度(Ci)、非光化学猝灭系数(NPQ) 和叶黄素循环脱环氧化状态(A + Z) / (V +A + Z) 的升高, 而对气孔导度(Gs)和PSⅡ原初光能转换效率(Fv/Fm) 影响很小。SA和OA处理可使光氧化胁迫下叶黄素循环库增加, 提高叶绿素、类胡萝卜素含量。这些结果说明, SA 和OA对光氧化胁迫下黄瓜叶片光合机构的破坏具有保护作用。

Effects of Salicylic Acid and Oxalate on Photosynthetic System and Xanthophyll Cycle in Cucumber Leaves under Photooxidative Stress

Effects of exogenous salicylic acid ( SA) and oxalate (OA) on photosynthesis, chlorophyll fluorescence and xanthophyll cycle in cucumber leaves under photooxidative stress induced bymethyl viologen (MV) were studied. The cucumber leaveswere sp rayed with SA 0.2 mmol·L ^{- 1} and OA 5 mmol·L ^{- 1} solution for 2 days before photooxidative stress by smearing MV 500 μmol·L^-1 on leaf surface. The results showed that both SA and OA pretreatment could inhibit the decreases in photosynthetic rate ( Pn) , transp iration rate (Tr) , quantum yield of PSⅡ (ΦPSⅡ) , chlorophyll photochemical quenching ( qP) and the increases in intercellular CO₂ concentration (Ci) , chlorophyll non-photochemical quenching (NPQ) and (A + Z) / (V +A + Z) ( the de-epoxidation extent of xanthophyll cycle) caused by photooxidative stress, but had little effect on stomatal conductance (Gs) and intrinsic photochemical efficiency of PSⅡ ( Fv/Fm). The decreases in xanthophyll cycle pool size, chlorophyll and carotenoid contents caused by photooxidative stress were also inhibited by SA and OA pretreatment. These results suggested that both SA and OA has the protective role against the damage of photosynthetic system during photooxidative stress.