Vacuolar-type H+-ATPase (V-ATPase), a multisubunit proton pump located on the endomembrane, plays an important role in plant growth. The Arabidopsis thaliana V-ATPase d subunit (VHA-d) consists of two isoforms; AtVHA-d1 and AtVHA-d2. In this study, the function of AtVHA-d2 was investigated. Histochemical analysis revealed that the expression of AtVHA-d1 and AtVHA-d2 was generally highly overlapping in multiple tissues at different developmental stages of Arabidopsis. Subcellular localization revealed that AtVHA-d2 was mainly localized to the vacuole. AtVHA-d2 expression was significantly induced by oxidative stress. Analysis of phenotypic and H2O2 content showed that the atvha-d2 mutant was sensitive to oxidative stress. The noninvasive microtest monitoring demonstrated that the net H+ influx in the atvha-d2 roots was weaker than that in the wild-type under normal conditions. However, oxidative stress resulted in the H+ efflux in atvha-d2 roots, which was significantly different from that in the wild-type. RNA-seq combined with qPCR analysis showed that the expression of several members of the plasma membrane H+-ATPase gene (AtAHA) family in atvha-d2 was significantly different from that in the wild-type. Overall, our results indicate that AtVHA-d2 plays a role in Arabidopsis in response to oxidative stress by affecting H+ flux and AtAHA gene expression.
Keywords: Arabidopsis; H+ flux; V-ATPase d subunit; oxidative stress; plasma membrane H+-ATPase; sensitive.