Abstract:

Brassica chinensis L. were foliarly applied with glycinebetaine (GB), as this species is unable to synthesis GB and sensitive to osmotic stress such as salt. The exogenous GB was easily absorbed and transported by the leaf of B. chinensis . Its application (0-20 mmol/L) enhanced the plant tolerance to salt stress. The treatment of 15 mmol/L GB significantly decreased the Na+ accumulation in leaf and root under NaCl stress. This difference in accumulating Na+ and K+ is caused by higher selectivity of root absorption. Furthermore, GB increased H+-ATPase activity of root plasma membrane evidently. This result strongly suggested that in root the decreased Na+ accumulation was caused by the GB accumulation that enhanced the extrusion of Na+ from the cell in some way through plasma membrane transporter, e.g. Na+/H+ antiport driven by H+-ATPase. The GB application was also found to stabilize the plasma membrane, to decrease the loss of chlorophyll, and to stimulate the osmosis induced proline response under salt stress.

甘氨酸甜菜碱增强青菜抗盐性的作用
许雯 孙梅好 朱亚芳 苏维埃*

（中国科学院上海植物生理研究所，上海2000032）

摘要：通过对青菜 (BrassicachinensisL .)叶面喷施甜菜碱 ,发现其易于为叶片所吸收并运至其他部位。一定浓度范围内的甜菜碱可明显增强青菜对盐胁迫的抗性。甜菜碱可显著降低盐胁迫下叶和根中Na+的累积 ,这种降低主要是根系对Na+、K+的选择性吸收能力增强所致。盐胁迫下甜菜碱导致根系质膜H+ ATPase活性提高了 45.1 % ,据此推测甜菜碱降低植株中Na+的累积很可能部分由于促进根系质膜的主动排Na+过程。另外 ,甜菜碱对抗盐性的增强还体现在对叶片质膜和叶绿素的稳定作用和对脯氨酸合成的促进。

关键词： 甜菜碱；青菜；盐胁迫；脯氨酸NA+累积；盐胁迫；质膜H+-ATPase

Key words: glycinebetaine, Brassica chinensis , proline, Na+ accumulation, salt stress, plasma membrane, H+-ATPase