外源ALA和Spd对低温弱光下辣椒幼苗光合作用及抗氧化系统的影响

Influence of Exogenous ALA and Spd on Photosynthesis and Antioxidant System of Low Temperature and Poor Light Affected Pepper Seedlings

【目的】探讨外源5-氨基乙酰丙酸(5-aminolevulinic acid,ALA)和亚精胺(Spd)对低温弱光下辣椒幼苗叶片影响及相关生理机理。【方法】以辣椒幼苗为试材,利用人工气候室模拟低温(15℃/5℃)(昼/夜)弱光(20—30μmol.m-2.s-1)逆境,通过叶面喷施0.5 mg.L-1ALA和0.5 mmol.L-1Spd,研究Spd和ALA对辣椒耐低温弱光的影响。【结果】ALA和Spd处理可减缓持续低温弱光下辣椒幼苗光系统II(PSII)最大光化学效率(Fv/Fm)、PSII实际光化学效率(ΦPSII)、光化学猝灭系数qP和PSII反应中心光能捕获效率(Fv'/Fm')的下降,同时显著提高了辣椒幼苗叶片净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr),并且显著提高了叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)抗氧化酶活性,同时减缓辣椒幼苗MDA含量和细胞膜透性的持续增大。可溶性蛋白质和脯氨酸(Pro)含量与耐性呈正相关。【结论】ALA和Spd能够提高低温弱光下辣椒幼苗的耐冷性与激活了辣椒的防御系统及保护了细胞膜系统有关;同时通过提高植株SOD、POD和CAT活性来促进辣椒幼苗活性氧代谢,从而保护细胞光合性能。

The objective of this experiment is to investigate the effect of 5-aminolevulinic acid（ALA） and spermidine（Spd） on the hot pepper（Capsicum annuum L.） and its mechanism with seedling leaves at low temperature and poor light.【Method】 The effect of Spd and ALA on continuing cold resistance of hot pepper was investigated by using hot pepper seedlings as the test materials under low temperature（15℃/5℃）（day/night） and poor light（20-30 μmol.m-2.s-1） adverse circumstances simulated by artificial climate chamber with foliar spray by ALA（0.5 mg.L-1） and Spd（0.5 mmol.L-1）.【Result】 The results showed that the treatment with Spd and ALA alleviated the decline of the maximal photochemical efficiency（Fv/Fm） of photosystem II（PSII）,the actual photochemical efficiency of photosystem II（ΦPSII）,photochemical quenching coefficient（qP） and the efficiency of light energy capture by open PSII reaction centers（Fv′/Fm′） under low temperature and dim light adverse circumstances,also significantly increased the net photosynthetic rate（Pn）,stomatal conductance（Gs）,transpiration rate（Tr） and the activity of superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT）,and alleviated continual enhancement of MDA content and membrane permeability.The content of soluble protein and proline was positively correlated with tolerance.【Conclusion】 The increasing cold resistance of hot pepper with ALA and Spd treatment under critical low temperature and dim light adverse circumstances is related to activated defensive system and protected cell membrane.Additionally,the increasing activity of SOD,POD and CAT also could promote metabolism of active oxygen to protect photosynthesis of cell.