SO_2诱导拟南芥保卫细胞凋亡

以拟南芥叶片下表皮为材料,研究了SO_2体内衍生物-亚硫酸钠和亚硫酸氢钠混合液(3:1,mmol·L~(-1)/mmol·L~(-1))对气孔保卫细胞的致死效应.结果表明,浓度1.0～5.0 mmol·L~(-1)的SO_2衍生物处理表皮3 h可引起保卫细胞死亡,死细胞出现核固缩、核断裂、凋亡小体等典型的核凋亡特征,且胁迫组细胞内活性氧和钙离子水平升高.蛋白酶抑制剂Z-Asp-CH_2-DCB和TLCK能减少SO_2衍生物诱导的细胞凋亡;过氧化氢酶(CAT)、抗坏血酸(AsA),及Ca~(2+)螯合剂乙二醇双四乙酸(EGTA)和Ca~(2+)通道抑制剂LaCl_3均可使SO_2衍生物诱发的细胞死亡率降低.0.1 mmol·L~(-1)的AsA或EGTA能降低胁迫组胞内的活性氧和Ca~(2+)水平,与死亡率降低相伴发生.以上结果表明,一定浓度的SO_2可诱导拟南芥保卫细胞凋亡,胁迫可能通过诱导活性氧产生、胞外钙内流,造成胞内Ca~(2+)浓度升高,引发细胞程序性死亡.

SO_2 Induces Programmed Cell Death in Arabidopsis Guard Cells

The effect of SO_2 derivatives on guard cell death was investigated in Arabidopsis thaliana. The cell death (PCD) occurred after epidermal strips exposed to SO_2 derivatives for 3 h,while reactive oxygen species (ROS) and Ca~(2+) levels increased within guard cells. However,the percentage of the cell death de-and Ca~(2+) levels increased by SO_2 exposure. Benzyoxycarbonyl-Asp-2, 6-dichlorobenzoyloxymethylketone(Z-Asp-CH_2-DCB) and N-tosyl-L-lysine chloromethylketone (TLCK) decreased cell death at concentrationthaliana via reactive oxygen species (ROS) production. ROS activates plasma membrane Ca~(2+) channels,leads to Ca~(2+) influx and an increase of intracelluar Ca~(2+) level,and induces finally cell death.