拟南芥金属蛋白酶FtSH4通过生长素与活性氧调控叶片衰老

植物金属蛋白酶Ft SH基因家族在拟南芥(Arabidopsis thaliana)中有12个成员,目前各基因的功能还不清楚。该文利用细胞生物学和遗传学方法初步分析了拟南芥FtSH4在叶片衰老中的功能。ftsh4-4突变体叶片中H_2O_2含量及细胞死亡率增加,叶绿素含量降低;此外,突变体中过氧化物酶基因表达上调,过氧化物酶活性增加,出现早衰表型。外源抗氧化剂As A、内源和外源生长素能够通过降低ftsh4-4体内H_2O_2含量、过氧化物酶基因的表达及过氧化物酶活性,恢复ftsh4-4叶片的衰老表型。ftsh4-4突变体中生长素响应因子基因ARF2和ARF7上调表达,外源生长素和抗氧化剂能够降低ARF2和ARF7的表达,并且ARF2突变能够降低ftsh4-4的H_2O_2含量并恢复其早衰表型。以上结果表明,FtSH4基因通过生长素与活性氧在调控植物叶片衰老中起重要作用。

Arabidopsis Metalloprotease FtSH4 Regulates Leaf Senescence Through Auxin and Reactive Oxygen Species

The plant metalloproteinases FtSH gene family has 12 members in Arabidopsis, and their functions are still unclear. In the present study, we analyzed the function of FtSH4 on leaf senescence using cell biology and genetics methods. The ftsh4-4 mutant displayed a premature leaf senescence phenotype with increased H₂O₂ content and cell death rate, decreased chlorophyll content, increased peroxidase gene expression and peroxidase activity. The ftsh4-4 leaf senescence phenotype could be rescued by applying the exogenous antioxidant AsA and endogenous or exogenous auxin by decreasing H₂O₂ content, peroxidase gene expression level and peroxidase activity. The expression of auxin response factor genes ARF2 and ARF7 was increased in the ftsh4-4 mutant and was reduced by exogenous auxin or AsA. Moreover, H₂O₂ content and the senescence phenotype of ftsh4-4 could be rescued by the arf2-8 mutant. These results indicate that FtSH4 gene plays an important role in the regulation of leaf senescence through auxin and reactive oxygen species.