SO_2诱导拟南芥气孔保卫细胞致死效应研究

SO_2 Induces Guard Cells Death in Arabidopsis thaliana

以拟南芥叶片下表皮为材料,研究了SO2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作用。结果表明,浓度0.5～4.5mmol·L-1的SO2衍生物处理表皮3h可引起保卫细胞死亡,细胞死亡率呈浓度依赖性增高。抗坏血酸(AsA)或过氧化氢酶(CAT)与SO2衍生物共同作用时,保卫细胞死亡率显著降低。Ca2+螯合剂乙二醇双四乙酸(EGTA)或Ca2+通道抑制剂LaCl3与SO2衍生物共同作用时,保卫细胞死亡率亦显著降低。研究发现,一定浓度的SO2可诱导拟南芥保卫细胞死亡,胁迫可能通过诱导活性氧、激活质膜钙通道,造成胞外Ca2+内流,引发细胞死亡。

The effects of SO2 derivatives on guard cells death were investigated in model plant Arabidopsis thaliana. The isolated epidermal strips were treated with various chemicals under white light for 3 h, stained with FDA, and examined with a fluorescence microscope. Randomly selected views on the tested epidermal strips were monitored to determine the number of viable cells and the total number of scored cells. SO2 derivatives, a mixture of sodium sulfite and sodium hisulfite （3：1, mmol·L^-1/mmol·L^-1）, significantly induced cell death at con- centrations from 0.5 to 4.5 mmol·L^-1. However, the percentage of the cell death decreased when the strips exposed to SO2 derivatives combined with ascorbic acid （AsA, 0.1, 1.0 mmol·L^-1） or catalase （CAT, 200 U·mL^-1）. The cell death percentage also decreased after the strips exposure to SO2 derivatives combined with EGTA （Ca^2＋ chelator, 0.1, 1.0 mmol·L^-1） or LaCl3 （Ca^2＋ channel blocker, 0.1mmol·L^-1）. The results of the present study indicated that SO2 caused cell death in A. thaliana via reactive oxygen species （ROS） production. ROS activated plasma membrane Ca^2＋ channels, led to Ca^2＋ influx and an increase of intracelluar Ca^2＋ level, and induced finally cell death.