H_2S对镉胁迫下白菜幼苗根系渗透胁迫的调节作用

Regulation of H_2S on Cd-induced osmotic stress in roots of Chinese cabbage seedling

以水培白菜幼苗为材料,研究了气体信号分子H_2S对重金属镉胁迫下白菜幼苗根系细胞膜透性和渗透调节物质的影响。结果表明,在2.5 mmol·L^(-1)和5 mmol·L^(-1)CdCl_2胁迫下,随处理时间的增加,白菜根系的膜脂过氧化产物丙二醛含量增加,白菜幼苗根细胞的相对电导率增大,细胞膜透性增大;H_2S的外源供体NaHS(1、5、10μmol·L^(-1))预处理,均使镉胁迫引起的白菜根细胞相对电导率显著下降并提高根部的相对含水量;5μmol·L^(-1)NaHS预处理可增加镉胁迫下白菜幼苗根部可溶性糖和脯氨酸的含量,可溶性蛋白和甜菜碱含量则无明显变化,1μmol·L^(-1)羟胺(H_2S生成抑制剂)处理降低了镉胁迫下可溶性糖和脯氨酸含量。因此,H_2S可以通过调节白菜幼苗根的渗透调节物质可溶性糖和脯氨酸的合成来降低镉对根系的伤害。

Hydrogen sulfide has showed the potential to enhance the resistance of plants to environmental stresses. In this study, regulation of gas transmitter H2S on the cell membrane permeability and the osmoticum in roots of Chinese cabbage seedings under Cd stresses was investigated. Cadmium stresses caused lipid peroxidation excessive accumulation in a time-and concentration-dependent manner, leading to higher relative conductivity and greater membrane permeability in cabbage root cells. Pretreatments with 1, 5, and 10μmol·L^-1 NaHS, donor of H2S, significantly reduced the relative conductivity increased by Cd stresses and increased water content in the roots. Under Cd stresses, the content of soluble sugar and proline was improved by the fumigation with NaHS, but was reduced by H2S synthesis inhibitor HA pretreatment. The present finding indicate that H2S alleviates Cd toxicity mainly through promoting the synthesis of soluble sugar and proline and then balancing the Cd-induced osmotic stress in cabbage seedling roots.