硒对油菜根尖镉胁迫的缓解作用

为研究镉胁迫对油菜根尖的毒性效应及硒的添加对该毒性效应的缓解作用,采用MS(Murashige and Skoog)培养基培养的方式,研究了0.2 mg·L-1硒对1 mg·L-1镉胁迫下油菜幼苗根系生长、根系构型、根尖膜系统完整性、亚细胞超微结构及细胞凋亡程度的影响.结果表明:镉胁迫下,硒的添加在一定程度上恢复了根系的生长,维持了根系的构型,使得总根长、总表面积和分叉数分别增加了33.28%、18.81%和21.66%;硒对根系形态的恢复作用主要表现在对直径小于1.0 mm的根系的恢复,直径小于1.0 mm的根系总根长提高了44.73%,总表面积提高了37.35%,总体积提高了32.88%;硒能够缓解镉对根尖细胞膜系统完整性的破坏;降低膜脂质过氧化程度,减少自由基的生成量,使得根尖O·-2含量降低了67.47%;并能维系细胞的形态和细胞器的结构完整性.然而,0.2 mg·L-1的硒并未显著降低根尖死亡细胞的数量,仅降低了晚期凋亡细胞的比例.

Alleviation of cadmium stress on root tip of rape seedlings by selenium

To investigate the alleviation effects of selenium (Se) on the cadmium (Cd) toxicity in rape root tips, we investigated the effects of 0.2 mg · L^-1 Se on root growth, root morphological characteristics, integrity of membrane, ultrastructure, and programmed cell death (PCD) in the roots tips of rape seedlings. MS (Murashige and Skoog) experiments showed that addition of 0.2 mg · L^-1 exogenous Se significantly alleviates the inhibitory effect of 1 mg · L^-1 Cd stress on the growth of rape seedlings. Total length, total surface and forks number of root were promoted by 33.28%, 18.81% and 21.66% respectively. The roots with diameter below 1 mm were restored and the total root length increased by 44.73%. Damage of the membrane system caused by Cd deceased, and levels of lipid peroxides and superoxide free radicals (O₂^·-) induced by Cd also decreased. The membrane permeability and ultrastructure of root tip were considerably recovered due to the application of Se. However, supplementation of the medium with Se did not reduce the number of cell death in root tip, but reduced the ratio of late period apoptotic cell. Meanwhile, there was no significant role of selenium on the integrity of DNA and other cytogenetic material.