ABA诱导玉米叶质外体H_2O_2积累的机制

The Mechanism of ABA-induced Apoplastic H_2O_2 Accumulation in Maize Leaves

通过组织化学染色和电镜观察并结合酶活性分析表明,ABA可通过诱导玉米(ZeamaysL.)叶片质膜NADPH氧化酶、细胞壁POD及质外体PAO活性的升高,使其质外体产生H2O2;其中质膜NADPH氧化酶起主要作用。

In maize （Zea rnays L.） cells, the sources of apoplast hydrogen peroxide （H2O2） induced by abscisic acid （ABA） has been proposed. Histochemical and cytochemical localization of ABA-induced H2O2 production in leaves of maize was examined, using 3, 3-diaminobenzidine （DAB） and cerium chloride （CeCl3） staining respectively. Pretreatment with two different inhibitors for each enzymes, with diphenylene iodonium （DPI） and imidazole against NADPH oxidase, NaCN and NaN3 against peroxidases （POD）, and quinacrine and guazatine against polyamine oxidases （PAO）, reduced H2O2 accumulation induced by ABA. Among them, NADPH oxidase inhibitors arrested the production of apoplastic H2O2 most strongly （Figs. 1, 2）. Further studies showed that exogenous ABA treatment could enhance the activities of plasma membrane （PM） NADPH oxidase, cell wall POD and apoplast PAO significantly. Moreover, the activity of PM NADPH oxidase kept increasing before 1.5 h, while the other two enzymes began to decrease at 0.5 h within 2 h by ABA treatment （Fig.3）. The results suggest that exogenous ABA treatment can lead to significant increases in H2O2 accumulation in apoplast through up-regulating the activities of the PM NADPH oxidases, cell wall POD and apoplast PAO, of which the first one plays a central role in ABA-induced apoplastic H2O2 accumulation.