, Volume 30, Issue 5, pp 1149-1157
Date: 14 Mar 2012

Cloning and Characterization of MxVHA-c, a Vacuolar H+-ATPase Subunit C Gene Related to Fe Efficiency from Malus xiaojinensis

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The vacuolar H+-ATPase plays a crucial role in secondary transport and in plant response to environmental stress. In this study, a vacuolar H+-ATPase (MxVHA-c) gene, consisting of an ORF of 498 base pairs and 165 amino acid residues, has been cloned from the iron-efficient genotype of Malus xiaojinensis. Subsequently, this gene has been targeted to the tonoplast using transient expression analysis. Quantitative real-time (qRT) PCR results reveal that the MxVHA-c gene is expressed in both roots and leaves of Fe-deficient plants; however, it is sensitive to iron stress in roots. This suggests that MxVHA-c expression in roots may mediate iron-dependent responses. MxVHA-c expression is up-regulated following exogenous treatment with abscisic acid (ABA) and down-regulated following treatment with CaCl2. Overexpression of the MxVHA-c gene in yeast strains has revealed that MxVHA-c transiently alleviated cadmium toxicity via the Cd2+/H+ antiport protein. H+-ATPase activity is slightly increased in yeast overexpressing the MxVHA-c gene compared to that in yeast transformed with an empty vector. In addition, this transgenic yeast strain can grow in a liquid medium containing 40 μM ferrozine. These findings may provide useful information in elucidating molecular mechanisms that mediate resistance to iron deficiency.

Qian Zhang and Yi Wang contributed equally to this work.