干旱胁迫下外源ALA对烤烟幼苗光合特性和抗氧化能力的影响

Effects of Exogenous ALA (5-aminolevulinic acid) on Photosynthesys and Antioxidant System of Flue-cured Tobacco Seedlings under Drought Stress

为进一步探究外源5-氨基乙酰丙酸(ALA)对干旱胁迫下烟草幼苗抗旱能力的作用机理,以烤烟品种豫烟10号幼苗为试验材料,采用营养液培养的方法,研究叶面喷施不同浓度的(0~80 mg/L)外源ALA对干旱胁迫下烤烟幼苗烤烟光合特性和抗氧化能力的影响。结果表明干旱胁迫下烤烟叶片细胞活性氧和硫代巴比妥酸(TBARS)含量增加,叶绿体遭到破坏,光合速率降低,植物生长受到抑制。干旱胁迫下外源ALA能够显著降低烤烟叶片活性氧水平,提高抗氧化酶活性,以喷施20 mg/L ALA效果最为显著。其中与PEG处理相比,净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)分别提高96.19%、96.79%和132.43%,抗氧化物酶(SOD、POD、CAT、APX)活性分别提高49.05%,61.97%,64.17%和70.08%。喷施适宜浓度的外源ALA可有效提高烤烟叶片光合特性和抗氧化能力,缓解活性氧伤害,从而增强烤烟幼苗对干旱胁迫的适应能力。

To further investigate the function of exogenous ALA in strengthening the ability of tobacco seedlings to resist drought,the effects of different concentrations(0-80 mg/L)of exogenous ALA on photosynthetic characteristics and antioxidant activities of flue-cured tobacco(Nicotiana tabacum L.)seedlings of Yuyan 10 were studied using the method of hydroponic nutrient solution with polyethylene glycol(PEG-6000)simulating drought stress artificially.The results showed that chlorophyll contents and photosynthetic characteristics of flue-cured tobacco seedlings were significantly inhibited under drought stress.Exogenous ALA could increase chlorophyll contents,photosynthetic characteristics,the activities of antioxidant enzymes,decrease the level of active oxygen metabolism and growth inhibition of flue-cured tobacco seedlings.And 20 mg/L ALA was considered to be the optimal concentration,with 33.09%,45.04%,31.27%higher net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs),and 49.05%,61.97%,64.17%,70.08%higher activities of SOD,POD,CAT and APX.In conclusion,spraying exogenous ALA with appropriate concentration could effectively enhance the antioxidant capacity and photosynthetic pigment,relieve oxidative damage,thus enhance the flue-cured tobacco seedling’s ability to adapt to drought stress.