外源钙对盐胁迫下不同衰老类型小麦幼苗生长生理的缓解效应

Alleviative effect of exogenous calcium ions on growth physiology of different senescence types of wheat seedlings under salt stress

【目的】探讨延迟衰老型小麦Triticum aestivum与早衰型小麦的耐盐性,确定钙缓解小麦盐胁迫的最佳浓度及其机制。【方法】选用小麦加倍单倍体群体(DH)中的早衰株系DH70和延迟衰老株系DH106作为材料,以预实验所筛选的300 mmol·L^(-1)盐溶液对小麦进行胁迫,比较2个株系之间的耐盐性,再以不同浓度(5、10、20、40、60 mmol·L^(-1))氯化钙(CaCl_(2))溶液对盐胁迫下的小麦进行处理,确定CaCl_(2)溶液缓解盐胁迫的最佳浓度。【结果】①300 mmol·L^(-1)盐溶液胁迫显著抑制了小麦种子的萌发和幼苗的生长,且延迟衰老型小麦DH106表现出更好的耐盐性(P<0.05)。②施加不同浓度CaCl_(2)溶液均一定程度上缓解了盐害,使2个株系小麦的发芽率、苗长、根长和鲜质量等指标较300 mmol·L^(-1)盐胁迫处理均显著增加(P<0.05),超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性较盐胁迫处理显著提高(P<0.05),而丙二醛(MDA)质量摩尔浓度较盐胁迫处理显著下降(P<0.05),并且以40 mmol·L^(-1) CaCl_(2)处理缓解效果最佳。③在40 mmol·L^(-1) CaCl_(2)处理下,早衰株系DH70的SOD、POD活性分别提高了58.0%、43.5%,MDA质量摩尔浓度下降了33.0%,延迟衰老株系DH106的SOD、POD活性分别提高了52.9%、42.3%,MDA质量摩尔浓度下降了21.1%。【结论】盐胁迫显著抑制了小麦的正常生长发育,且延迟衰老型小麦表现出较好的耐盐性。外源施加CaCl_(2)可提高小麦抗氧化酶活性、降低MDA质量摩尔浓度,增强小麦耐盐能力,并且以浓度为40 mmol·L^(-1)处理效果最佳。

[Objective]This study,with an exploration of the salt tolerance of delayed aging wheat(Triticum aestivum)and premature aging wheat,is aimed to determine the optimal concentration and mechanism of calcium to alleviate salt stress in wheat.[Method]First,with the premature senescence strain DH70 and delayed senescence strain DH106 in the wheat doubled haploid(DH)population selected as materials,the wheat was subjected to stress with a 300 mmol·L^(−1) salt solution selected from the preliminary experiment before a comparison was made of the salt tolerance between the two materials.Then,different concentrations(5,10,20,40,60 mmol·L^(−1))of calcium chloride solution were used to treat wheat under salt stress before the optimal concentration of calcium chloride solution to alleviate salt stress was determined.[Result](1)The stress of 300 mmol·L^(−1) salt solution significantly inhibited the germination of wheat seeds and the growth of seedlings, and the delayed aging type of wheat DH106 showed better salt tolerance (P<0.05). (2)The application of different concentrations of CaCl_(2) solution alleviated the salt injury to a certain extent, so that the germination rate, seedling length, root length and fresh weight of the two materials of wheat were significantly increased compared with those with 300 mmol·L^(−1) salt stress treatment (P< 0.05) and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were significantly increased compared with those after salt treatment (P<0.05), while the content of malondialdehyde (MDA) was significantly decreased compared with that after salt treatment (P<0.05), with the best relief effect achieved with 40 mmol·L^(−1) CaCl_(2) treatment. (3)Under the treatment of 40 mmol·L^(−1) CaCl_(2), the SOD and POD activities of the premature aging strain DH70 increased by 58.0% and 43.5%, respectively, while the MDA content decreased by 33.0% and the SOD and POD activities of the delayed aging strain DH106 increased by 52.9% and 42.3%, respectively, whereas the MDA content decreased by 21.1%. [Conclusion] Salt stress significantly inhibited the normal growth and development of wheat, and delayed senescence type wheat showed good salt tolerance exogenous application of CaCl_(2) can increase wheat antioxidant enzyme activity, reduce MDA content, and enhance wheat salt tolerance. And the best treatment effect is achieved with a concentration of 40 mmol·L^(−1) CaCl_(2).