外源ALA对NaCl胁迫下酸枣幼苗光合特性与膜脂过氧化的影响

【目的】研究NaCl胁迫下外源ALA对酸枣幼苗叶绿素含量、光合特性及膜脂过氧化的影响,筛选缓解NaCl胁迫的最佳ALA处理浓度。【方法】以酸枣幼苗为试材,测定幼苗叶片在150 mmol/L NaCl胁迫下喷施不同浓度的外源ALA(50、75、100和150 mg/L)后第3 d和第6 d的叶绿素含量、光合特性、抗氧化酶活性及MDA含量的影响。【结果】150 mmol/L NaCl胁迫下酸枣幼苗叶片的叶绿素含量、光合特性及抗氧化酶活性均显著下降。喷施外源ALA可以显著提高NaCl胁迫下酸枣叶片叶绿素含量光合指标和抗氧化酶的活性,降低Ci和MDA含量。其中,以ALA处理后第3 d的T3处理的效果最佳,叶绿素a、总叶绿素含量、Pn、Gs、Tr、SOD、POD和CAT分别增加了67.50%、72.74%、85.71%、135%、87.06％、20.79%、69.59%、和61.25%;Ci和MDA分别降低了22.53%和24.71%。【结论】NaCl胁迫对酸枣造成了明显的损害,抑制其光合作用,破坏了抗氧化酶系统;喷施外源ALA能够通过提高叶绿素含量,增强抗氧化酶活性,促进叶片的光合作用,缓解NaCl胁迫对酸枣幼苗的伤害,提高酸枣的耐盐性;Chl a、Chl、SOD和CAT可以作为评价喷施不同浓度ALA对NaCl胁迫缓解效果的主要指标;不同浓度的外源ALA均能有效缓解NaCl胁迫对酸枣幼苗的伤害,并以100 mg/L ALA处理在第3 d缓解效果最佳。

Effects of Exogenous ALA on Photosynthesis and Membrane Peroxidation in the Leaves of Jujube Seedlings under NaCl Treatment

【Objective】 To investigate the effects of exogenous 5-aminolevulinic acid (ALA) on chlorophyll content, photosynthetic characteristics and membrane lipid peroxidation of jujube seedlings under NaCl stress in the hope of screening out the optimal ALA treatment concentration for NaCl stress after comprehensive evaluation. 【Method】 With jujube seedlings as test materials, different concentrations of exogenous 5-aminolevulinic acid (ALA, 50, 75, 100 and 150 mg/L were sprayed on seedling leaves under 150 mmoL/L NaCl stress to study the effects of chlorophyll content, photosynthetic characteristics, antioxidant enzyme activities and MDA content on the third and sixth days after. 【Result】 The chlorophyll content, photosynthetic characteristics and antioxidant enzyme activities of leaves of jujube seedlings decreased significantly under the stress of 150 mol/L NaCl. Spraying exogenous ALA could significantly increase the photosynthetic index and antioxidant enzyme activity of chlorophyll content in leaves of jujube under NaCl stress, and reduce the content of Ci and MDA. Among them, T3 treatment on the third day after ALA treatment had the best effect, chlorophyll a, total chlorophyll content, Pn, Gs, Tr, SOD, POD and CAT increased by 67.50%, 72.74%, 85.71%, 135%, respectively. 87.06%, 20.79%, 69.59%, and 61.25%; Ci and MDA decreased by 22.53% and 24.71%, respectively. 【Conclusion】 NaCl stress caused obvious damage to jujube, inhibited photosynthesis and destroyed antioxidant enzyme system. Spraying exogenous ALA could promote leaf photosynthesis by increasing chlorophyll content and enhancing antioxidant enzyme activity. The injury of jujube seedlings was alleviated by NaCl stress, and the salt tolerance of jujube seedlings was improved. Principal component analysis showed that Chl a, Chl, SOD and CAT could be used as the main indexes to evaluate the effects of spraying different concentrations of ALA on NaCl stress. The comprehensive evaluation showed that different concentrations of exogenous ALA could effectively alleviate the damage of jujube seedlings induced by NaCl stress, and the best effect was achieved on the third day with 100 mg/L ALA treatment.