Molecular cloning and functional characterization of the Aluminum-activated malate transporter gene MdALMT14

The salinity of soil severely restricts the rate of land use and crop productivity. Plants have developed complex mechanisms, including osmotic adjustment, to resist salt stress. Here, we report that the MdALMT14 gene in the apple is a homolog of the Arabidopsis malate acid transporter gene AtALMT14. The expression of MdALMT14 was induced by salt treatment. The ectopic expression of MdALMT14 in Arabidopsis decreased the malondialdehyde (MDA) content and the relative electronic conductivity under salt conditions. In addition, our results showed that MdALMT14 impacted salt tolerance by promoting the accumulation of malic acid in Arabidopsis. The overexpression of MdALMT14 increased salt tolerance in apple calli. Taken together, these findings provide evidence that the apple Aluminum-activated Malate Transporter MdALMT14 is involved in salt stress tolerance and the regulation of malic acid content. These data provide new ideas for further attempts to improve stress tolerance and fruit quality through cultivation and breeding methods.