水孔蛋白协助玉米副卫细胞中H_2O_2的跨膜转运

Aquaporin facilitates transmembrane diffusion of H_2O_2 in maize subsidiary cells

【目的】探索玉米气孔副卫细胞中H_2O_2的来源,以阐明禾本科植物气孔运动过程中保卫细胞和副卫细胞协同调节的机理。【方法】采用细胞化学方法对H_2O_2进行亚细胞荧光定位,以Tubulin和GAPDH为内参基因,利用qPCR技术,对玉米水孔蛋白基因ZmPIP2;4、ZmPIP2;5和ZmPIP2;6表达量进行分析,从而确定水孔蛋白协助玉米副卫细胞中H_2O_2的跨膜转运。【结果】光暗处理组,加水孔蛋白抑制剂AgNO_3与不加AgNO_3副卫细胞中的H_2O_2积累相反;外源H_2O_2引起副卫细胞中H_2O_2积累,先加入水孔蛋白抑制剂AgNO_3再加外源H_2O_2处理后副卫细胞中H_2O_2不积累;短细胞发生后,副卫细胞中的H_2O_2开始积累,同时ZmPIP2;5基因的相对表达量上调;随着水分胁迫程度增加,ZmPIP2;4、ZmPIP2;5、ZmPIP2;6基因的相对表达量随短细胞发生上调。【结论】水孔蛋白具有转运H_2O_2的功能,玉米叶片下表皮副卫细胞中的H_2O_2是外源的,其积累和清除可能与水孔蛋白ZmPIP2;5的转运有关。

[Objective] This study researched the sources of H2O2 in maize subsidiary cells to clarify the co-regulation mechanism of guard cells and subsidiary cells in grassy stomatal movement. [Method] This study researched the cell localization of H2O2 by cytochemical fluorescent probe and analyzed the gene ex- pression of ZrnPIP2 ;4, ZmPIP2 ; 5, ZmPIP2 ; 6 by qPCR technology, with Tubulin and GAPDH as refer- ence genes. Then the fact of aquaporin facilitates transmembrane diffusion of H2O2 in maize subsidiary cells was confirmed. [Result] Under light and dark treatments, the accumulation of H2O2 in subsidiary cells was opposite to the control group supplemented with aquaporin inhibitor AgNO3. Exogenous H2O2 caused H2O2 accumulation in subsidiary cells,but aquaporin inhibitor AgNO3 added before the addition of exoge- nous H2O2 did not cause H2O2 accumulation. After short cells appeared, H2O2 started to accumulate in sub- sidiary cells,at the same time the gene expression of ZmPIP2;5 was upregulated. After short cells ap- peared,the expressions of ZmPIP2 ; 4, ZmPIP2 ; 5 and ZmPIP2 ; 6 were upregulated when increased soil water shortages. [Conclusion] Aquaporin can transport He O2 in leaf epidermis of maize and H2O2 in sub- sidiary cells was exogenous, whose accumulation and elimination were possibly mediated by aquaporinZmPIP2 ; 5.