The Apple Lipoxygenase MdLOX3 Regulates Salt Tolerance and ABA Sensitivity

Various abiotic stresses, particularly salinization, restrict plant growth and yield around the world. Lipoxygenases play essential functions in coping with various stresses. In the present study, we found an apple (Malus domestica) homolog of Arabidopsis lipoxygenase3, named MdLOX3. MdLOX3 has a typical conserved lipoxygenase domain. MdLOX3 was expressed in all tissues of apple and was highly expressed in the root and flesh tissues by a qRT-PCR analysis. In addition, the promoter of MdLOX3 consists of multiple response elements. Various abiotic stresses and ABA treatment can induce the expression of MdLOX3. The overexpression of MdLOX3 in apple calli enhanced the ability to tolerate salt stress, and the heterotopic expression of MdLOX3 in Arabidopsis elevated salt stress tolerance via enhancing the ability of scavenging ROS. Furthermore, the overexpression of MdLOX3 in transgenic plants significantly reduced the sensitivity to ABA. Through the above, this work demonstrated that MdLOX3 played an active position in salt resistance and decreased the sensitivity to ABA, providing a theoretical reference for studying the role of MdLOX3 in abiotic stresses in apple.