NO体外供体硝普钠诱导蚕豆气孔保卫细胞死亡机理研究

Sodium Nitroprusside Induces Guard Cell Death in Vicia faba

为分析NO在植物细胞死亡过程中的作用,以蚕豆表皮条和NO体外供体硝普钠(SNP)及NO信号途径抑制剂为材料,采用表皮条生物法,探讨SNP对蚕豆叶面保卫细胞的毒性机理。结果表明:(1)0.5～9mmol·L-1的SNP可使蚕豆气孔保卫细胞活性降低,部分细胞死亡,且随着SNP浓度的增高细胞死亡率增高。(2)凋亡抑制剂Z-Asp-CH2-DCB或TLCK可显著降低SNP诱发的保卫细胞死亡率。(3)抗坏血酸(AsA)、过氧化氢酶(CAT)、Ca2+螯合剂EGTA或Ca2+通道抑制剂LaCl3与SNP共同作用时,细胞死亡率显著降低。(4)NO清除剂c-PTIO、MAPK激酶抑制剂PD98059和鸟苷酸环化酶抑制剂ODQ亦能有效阻止SNP诱发的细胞死亡。研究发现,较高浓度的SNP可诱导蚕豆保卫细胞程序性死亡,SNP诱发植物细胞死亡与胁迫组保卫细胞内NO、ROS和Ca2+水平升高有关,cGMP和MAPK参与了SNP诱发的细胞死亡。

In order to understand the role of nitric oxide （NO） in plant cell death,we investigated the toxic mechanism of SNP on Vicia faba guard cell by using epidemal strips assays together with nitric oxide do- nor sodium nitroprusside （SNP） and some inhibitors of the NO signaling pathways. The experimental re- sults showed that：（1）SNP treatment significantly decreased cell viability and induced cell death at concen- trations from 0.5 to 9 mmol·L^- 1. （2） Two types of specific caspase inhibitors, Z-Asp-2,6 -dichlorobenzoy- loxymethylketone （Z-Asp-CH2-DCB） and Na-tosyl-Lys-chloromethyl keton （TLCK）,significantly blocked SNP-induced cell death. （3）Antioxidants ascorbic acid （AsA） and catalase （CAT） also inhibited SNP-in- duced guard cell death. Both Ca^2＋ chelating agent ethylene glycol bis （2-aminoethyl） tetraacetic acid （EGTA） and Ca^2＋ channel blocker LaCl3 decreased the cell death rate caused by SNP. （4）Application of NO scavenger c-PTIO,and inhibitors of mitogen-activated protein kinase （MAPK） （PD98059） or guanylate cyelase （ODQ） significantly inhibited SNP-induced cell death. The results of the present study showed that SNP caused programmed cell death in Vicia guard cells. Intracellular NO,ROS and Ca^2＋ as well as MAPK and cGMP molecules participated in the process of SNP-induced programmed cell death.