Heterologous expression of TuCAX1a and TuCAX1b enhances Ca and Zn translocation in Arabidopsis.

TuCAX1a and TuCAX1b improved Ca and Zn translocation and TuCAX1b enhanced Ca, Zn, Mn and Fe content when exposed to Cd; Cd translocation was inhibited under Ca and Zn. Cation/H antiporters (CAXs) are involved in the translocation of Ca and various metal ions in higher plants. In the present study, TuCAX1a and TuCAX1b, two cation/H antiporters, were isolated from the diploid wheat Triticum urartu, and their metal cation translocation functions investigated. TuCAX1a and TuCAX1b showed abundant tissue-specific expression in the internode and beard, respectively, and their expression levels were increased in shoots exposed to Cd, Zn and Ca. Plant phenotype analysis showed that overexpression of TuCAX1a and TuCAX1b could improve the tolerance of Arabidopsis to exogenous Ca and Zn. In the plant shoots and roots, the contents of Ca and Zn were higher than wild-type plants under Ca and Zn treatments, indicating that TuCAX1a and TuCAX1b can enhance Ca and Zn translocation. Ca, Zn, Mn and Fe contents showed higher accumulation in TuCAX1b-transgenic Arabidopsis shoots than in wild-type plants exposed to Cd, and the translocation of Cd was inhibited under Ca and Zn. Overall, the present study provides a novel genetic resource for improving the uptake of microelements and reducing accumulation of toxic heavy metals in wheat.