The HD‐Zip I transcription factor MdHB7‐like confers tolerance to salinity in transgenic apple (Malus domestica).

Salinity is a major environmental constraint that substantially limits global agricultural productivity. HD‐Zip I transcription factors are involved in plant responses to salt stress, but little is known about the HD‐Zip I genes in apple (Malus domestica). Here, we characterized the function of an apple HD‐Zip I gene (MdHB7‐like) and report that its expression is induced by salt stress. To further explore its role in salt stress, we created MdHB7‐like overexpressing and RNAi transgenic apple plants. The overexpression of MdHB7‐like improved the photosynthetic performance and reduced ROS and Na+ accumulation under salt stress. Plants that overexpressed MdHB7‐like also showed increased accumulation of proline and soluble sugars, which may have played an important role in their salt stress tolerance. RNAi suppression of MdHB7‐like had the opposite effects. Together, our results demonstrate that MdHB7‐like is an important regulator of salt tolerance in apple. Our results provide new insights for future research on the mechanisms by which MdHB7‐like promotes salt tolerance and provide a potential target for molecular breeding in apple. [ABSTRACT FROM AUTHOR]