外源甜菜碱对桑树抗盐生理的影响及其作用机理的研究

为探讨提高桑树抗逆境反应的新途径,对桑树扦插幼苗叶面喷施甘氨酸甜菜碱,调查外源甜菜碱对桑树生长发育及抗盐生理的影响,测定不同处理条件下桑树体内的甜菜碱含量。试验结果表明:在盐胁迫条件下,叶面施用甜菜碱可以提高叶片中叶绿素、可溶性糖及脯氨酸的含量,并保持叶片适当含水率和K+/Na+离子平衡,减轻盐胁迫对桑树枝叶生长的抑制作用。盐胁迫或叶面喷施甜菜碱均可显著诱导桑叶和根部内源甜菜碱的合成与积累,表明桑树属于甜菜碱积累型植物,外源甜菜碱对桑树抗盐性的增强效应可能与甜菜碱积累及相关生理过程有关。

Studies on Physiological Effects of Exogenous Betaine on the Salt Tolerance and Their Mechanisms in Mulberry

To explore the new approaches to enhance the stress tolerance of mulberry,the effects of exogenous glycinebetaine on the growth,development and the physiological responses to salt stress were investigated after the glycinebetaine was foliarly sprayed to mulberry cuttings.The contents of glycinebetaine in mulberry cuttings with different treatments were measured by nuclear magnetic resonance method.The results showed that foliar application of betaine increased the contents of chlorophyll,soluble sugar and proline in leaves,maintained the appropriate water content and K~(+)/Na~(+)ion equilibrium,and alleviated inhibition of stems and leaves by salt stress.Both salt stress and foliar application of betaine could induce the synthesis and accumulation of endogenous glycinebetaine in leaves and roots.Therefore,it is suggested that mulberry is a kind of plants accumulating glycinebetaine,and the enhancement of exogenous betaine to salt tolerance of mulberry may be attributed to the accumulation of glycinebetaine and related physiological processes.