Overexpression of MxWRKY53 increased iron and high salinity stress tolerance in Arabidopsis thaliana

Abiotic stresses, such as iron deficiency and high salinity, affect apple growth and development. WRKY transcription factors (TFs) are widely involved in the responses of plants to adverse stresses. In the present study, a new WRKY gene was isolated from Malus xiaojinensis and designated as MxWRKY53. Subcellular localization showed that MxWRKY53 was localized to the nucleus. The expression level of MxWRKY53 was highly affected by salt, low Fe, and high Fe stresses in M. xiaojinensis seedlings. When MxWRKY53 was introduced into Arabidopsis thaliana, it greatly enhanced the salt and Fe tolerance. When dealt with high and low Fe stresses, the overexpression of MxWRKY53 in transgenic A. thaliana resulted in higher levels of root length, fresh weight, and contents of chlorophyll and Fe than wild type (WT). Increased expression of MxWRKY53 in transformed A. thaliana also contributed to higher contents of chlorophyll and proline, and higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), while malondialdehyde (MDA) content was lower, especially in response to salt stress. Therefore, these results show that MxWRKY53 plays a positive role in the process of plant resistance to salt, low Fe, and high Fe stresses.