NaCl胁迫对不同耐盐性玉米自交系萌动种子和幼苗离子稳态的影响

Ion homeostasis in germinating seeds and seedlings of three maize inbred lines under salt stress

盐胁迫影响植物组织的离子分布,不同品种间存在差异。以玉米耐盐自交系81162和8723及盐敏感自交系P138为材料,研究了不同浓度(0、60、140、220 mmol/L)Na Cl胁迫下萌动期种子和幼苗的不同部位中Na+、K+、Ca2+含量以及K+/Na+和Ca2+/Na+比值的变化,旨在探讨不同自交系耐盐性差异的原因。结果表明,在萌动种子中,3个玉米自交系中的Na+积累量表现为种皮>胚>胚乳,K+累积表现为胚>种皮>胚乳;幼苗中,Na+积累表现为根>茎>叶。随着Na Cl浓度的增加,3个玉米自交系萌动种子和幼苗中的Na+含量逐渐升高,但是萌动种子中耐盐自交系81162和8723的Na+增加幅度小于盐敏感自交系P138,Na+含量小于盐敏感自交系P138;幼苗中耐盐自交系81162和8723的Na+增加幅度大于盐敏感自交系P138,幼苗根中Na+含量大于盐敏感自交系P138;茎叶中的Na+含量小于盐敏感自交系P138。随着Na Cl浓度的增加,萌动种子和幼苗中的K+和Ca2+含量逐渐降低。K+离子在耐盐自交系81162和8723萌动种子和幼苗中的降低幅度小于盐敏感自交系P138;Ca2+离子在耐盐自交系81162和8723幼苗中的降低幅度小于盐敏感自交系P138;而在萌动种子中3个自交系Ca2+的流失差异不大。耐盐自交系81162和8723萌动种子和幼苗中K+含量都大于盐敏感自交系P138。耐盐自交系81162和8723的萌动种子和幼苗根中Ca2+含量都大于盐敏感自交系P138;幼苗叶片中则小于盐敏感自交系P138。萌动种子和幼苗中K+/Na+和Ca2+/Na+均随着Na Cl浓度的升高而降低,K+/Na+比值表现为耐盐自交系81162和8723大于盐敏感自交系P138。耐盐自交系81162和8723通过调节离子平衡维持萌动种子和幼苗中较高的K+/Na+比值从而提高耐盐性。

Salt stress affects ion distribution in plant tissues. These salt-induced changes in ion distribution differ among plant varieties. In this study,we analyzed salt-tolerant inbred lines（ 8723 and 81162） and a salt-sensitive inbred line（ P138） of maize under varying degrees of salt stress（ 0,60,140,220 mmol /L Na Cl） to explore the reasons for differences in salt resistance among the inbred lines. We measured the concentrations of Na＋,K＋,and Ca2＋in the testa,embryo,endosperm,root,stem,and leaf tissues,and determined the ratios of K＋/ Na＋and Ca2＋/ Na＋in germinating seeds and seedlings. In germinating seeds,the Na＋concentration was highest in the testa,followed by the embryo,and then the endosperm; the K＋concentration was highest in the embryo,followed by the testa,and then the endosperm. In seedlings,the highest level of Na＋was in the root,followed by the stem,and then the leaves; the highest levels of K＋were in the root and stem,followed by the leaves. With increasing Na Cl concentrations in the salt treatment,the Na＋content increased gradually in germinating seeds and seedlings of the three maize lines. In germinating seeds,the range of the increase in Na＋content was smaller in the salt-tolerant lines 8723 and 81162 than in the salt-sensitive line P138,and the salt-tolerant lines accumulated less Na＋than did the salt-sensitive line. In seedlings,the range of the increase in Na＋content was larger in the salt-tolerant lines 8723 and 81162 than in the salt-sensitive line P138,and the salt-tolerant lines accumulated higher levels of Na＋in the roots and lower levels of Na＋in the stem and leaves. As the Na Cl concentration in the salt treatment increased,the K＋and Ca2＋contents decreased gradually in germinating seeds and seedlings of the three maize lines. In germinating seeds and in seedlings,the salt-tolerant lines 8723 and 81162 showed smaller ranges of decreased K＋contents and contained higher concentrations of K＋compared with the salt-sensitive line P138. In seedlings,the salt-tolerant lines 8723 and 81162 showed smaller ranges of decreased Ca2＋contents compared with the salt-sensitive line P138. However,in germinating seeds,there was no significant difference in the range of decreased Ca2＋content among the three maize lines. With increasing Na Cl concentrations in the salt treatment,the ratios of K＋/ Na＋and Ca2＋/ Na＋decreased in germinating seeds and seedlings. The K＋/ Na＋ratio was higher in the salt-tolerant lines 8723 and 81162 than in the salt-sensitive line P138.Germinating seeds and seedlings of the salt-tolerant lines 81162 and 8723 retained higher K＋/ Na＋ratios by adjusting ion homeostasis to improve salt resistance.