外源脯氨酸缓解玉米幼苗盐胁迫的效应

Mitigation of salt stress in maize seedlings by exogenous proline application

为探讨施用外源脯氨酸(Pro)对不同耐性玉米(Zea mays)幼苗盐胁迫的缓解效应,以耐盐自交系8723和盐敏感自交系P138为试材,在苗期以180 mmol·L^(-1) NaCl为胁迫条件,施加浓度为250μmol·L^(-1)的外源Pro,研究了盐胁迫下外源Pro对玉米幼苗生长以及相关生理指标的影响。结果表明,外源Pro处理可以有效缓解盐胁迫对玉米幼苗根系和地上部生长的抑制作用,同时提高超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性以及渗透溶质Pro与可溶性糖含量,减少丙二醛含量,稳定细胞膜结构。添加外源Pro后,还可以加强细胞内营养离子平衡性,降低Na^(+)对幼苗的毒害作用。此外,外源Pro对盐敏感品种具有更好地缓解效应。研究结果表明外源Pro可通过调节抗氧化物酶活性、渗透溶质及营养离子平衡能力来缓解盐胁迫对玉米幼苗的伤害作用,从而提高其耐盐性。

The mitigation effect of exogenous proline(Pro) application on salt stress was investigated in maize seedlings with different resistance levels using a salt-tolerant inbred line 8723 and salt-sensitive inbred line P138.The effects of exogenous Pro application on the growth parameters and related physiological indexes of maize seedlings under salt stress were studied under conditions of 180 mmol·L^(-1) NaCl and 250 μmol·L^(-1) exogenous Pro.The results showed that exogenous Pro treatment can effectively alleviate the inhibitory effect of salt stress on roots and shoots growth of maize seedlings,and increase the activities of superoxide dismutase,peroxidase,and catalase,as well as the levels of osmotic solute Pro and soluble sugars,reduce the content of malondialdehyde,and stabilize the structure of cell membranes.Exogenous Pro addition could also strengthen the intracellular ion balance and reduce the toxic effect of Na^(+) on maize seedlings.In addition,exogenous Pro had a better mitigation effect in the salt sensitive variety.The above results indicated that exogenous Pro could alleviate the effect of salt stress damage on maize seedlings by regulating antioxidant enzyme activities and osmotic solute and ion nutrient balances,thereby improving its salt tolerance.