外源脱落酸缓解二氧化硫对胡杨细胞的毒性

Exogenous abscisic acid alleviates sulfur dioxide-induced toxicity in Populus euphratica cells

二氧化硫(SO_2)是一种常见的大气污染物.前期研究表明,过氧化氢(H_2O_2)和一氧化氮(NO)参与调控SO_2诱导的胡杨细胞毒性.脱落酸(ABA)是一种植物逆境激素,目前关于ABA在植物细胞响应SO_2胁迫中的具体作用并不清楚.因此,本文以胡杨愈伤细胞为材料,采用SO_2衍生物处理,研究外源ABA在植物细胞SO_2毒性缓解中的作用及相关机制.结果发现:2 mmol·L^(-1)SO_2衍生物处理胡杨细胞9 h后,细胞电解质外渗率和细胞死亡率明显增加;外源施用5μmol·L^(-1)ABA可明显缓解SO_2对胡杨细胞的毒性,降低电解质外渗率和细胞死亡率.2 mmol·L^(-1)SO_2衍生物胁迫下,与SO_2单独处理组相比,添加外源ABA能够使胡杨细胞的抗坏血酸过氧化物酶(APX)和过氧化氢酶(CAT)活性分别提高23.9%和48.0%,从而减少胞内H_2O_2水平.此外,SO_2胁迫下,外施ABA后胡杨细胞的Pe Nia1、Pe Nia2基因表达受到明显抑制,细胞硝酸还原酶(NR)活性降低24.1%,胞内NO合成减少.以上结果表明,SO_2胁迫下,外源施加ABA可有效降低胡杨细胞内H_2O_2和NO水平,从而缓解SO_2对胡杨细胞的毒性.

Sulfur dioxide（ SO_2） is a common air pollutant. Previous studies revealed that hydrogen peroxide（H_2O_2） and nitric oxide（NO） regulated SO_2-induced cell toxicity of Populus euphratica. Abscisic acid（ ABA） is a phytohormone involved in plant response to abiotic stress. To date,the role of ABA in cell responses to SO_2 stress is largely unknown. In the present study,using SO_2 derivatives treatment,we investigated the relevant mechanisms of exogenous ABA alleviation of SO_2-induced toxicity in P. euphratica callus cells. The results showed that 2 mmol·L^（-1） SO_2 derivatives treatment（ 9 h）caused significant increase of cell death and electrolyte leakage rate of P. euphratica cells. Exogenous ABA（ 5 μmol·L^（-1）） application could alleviate SO_2-induced toxicity,decreasing the cell death rate and electrolyte leakage rate. Under 2 mmol·L^（-1） SO_2 derivatives exposure,exogenous ABA enhanced the activity of ascorbate peroxidase（ APX） and catalase（ CAT） by 23.9% and 48.0%,compared with SO_2 treatment alone,respectively,contributing to the scavenging of H_2O_2 within P. euphratica cells. Furthermore,exogenous ABA could remarkably inhibit Pe Nia1 and Pe Nia2 gene expression,and decrease nitrate reductase（ NR） activity by 24.1%,thus restricted NO generation within P. euphratica cells. These results suggested that exogenously applied ABA could alleviate SO_2-induced toxicity by reducing H_2O_2 and NO level in P. euphratica cells.