Cr^3＋胁迫对苦草叶片活性氧清除系统和叶细胞超微结构的影响

研究了不同浓度Cr^3＋胁迫对苦草[Vallisneria natarts（Lour．）Hara]叶片活性氧清除系统及细胞超微结构的影响。结果表明，随Cr^3＋浓度的提高（0．5-15．0mg·L^-1），苦草叶片中O2^-·和MDA含量、SOD和POD及CAT活性均呈现先上升后显著下降的变化趋势，且在10．0和15．0mg·L^-1 Cr^3＋胁迫条件下显著低于对照（P〈0．05）。在1．0mg·L^-1Cr^3＋胁迫条件下，O2^-·的含量达到最高（0．96 OD·g^-2）；在2．0mg·L^-1Cr^3＋胁迫条件下，MDA含量和SOD、POD及CAT活性最高。随Cr^3＋胁迫浓度的提高，苦草叶片细胞超微结构受损程度逐渐加深，导致核仁和高尔基体消失；线粒体脊突膨胀，线粒体膜受损并出现囊泡状结构；叶绿体变形、类囊体膨胀受损并最终导致叶绿体破损。表明高浓度Cr^3＋胁迫对苦草叶片细胞产生了不可逆的伤害。

Effects of Cr3+ stress on scavenging system of active oxygen and cell ultrastructure of Vallisneria natans leaf

Effects of Cr^3＋ stress with different concentrations on the scavenging system of active oxygen and cell uhrastructure of Vallisneria natans （Lour.） Hara leaf were investigated. The results showed that the contents of O2^-·and MDA and the activities of SOD, POD and CAT presented a trend of increasing firstly and then decreasing with increasing of Cr^3＋ concentration （0.5 -15.0 mg · L^-1） ,and in 10.0 and 15.0 mg · L^-1 Cr^3＋ stress conditions, these indexes were obviously lower than that of the control （P 〈 0.05）. The O2^-·content was the highest（0.96 OD · g^-1 ）in 1.0 mg · L^-1 Cr^3＋ stress condition, but the MDA content and the activities of SOD, POD and CAT reached the highest in 2.0 mg · L^-1 Cr^3 ＋ stress condition. With increasing of Cr^3 ＋ concentration, the injury degree of cell uhrastructure of V. natans leaf became more severe, and resulted in the nucleolus and golgi apparatus disappeared; the cristae of mitochondria swollen and mitochondria membrane damaged and then presented vacuolar mitochondria; the chloroplast deformed, the thylakoids swollen and eventually lead to chloroplasts break. It is concluded that the Cr^3＋ stress with high concentration has an irreversible injury to V. natans leaf cell.