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.

Zinc (Zn) is an essential trace element that plays a crucial role in plant growth and development, but excessive Zn can be stressful or even toxic to plants. The GLTP superfamily is critical for lipid metabolism and membrane stability maintenance, yet its function in plant Zn tolerance remains unclear. In this study, zinc stress treatment experiments were performed using transgenic apple calli, apple seedlings, Arabidopsis thaliana, and Solanum lycopersicum. Under Zn treatment, compared with the wild type (WT), the apple seedlings of the MbACD11 transgenic line exhibited significantly higher plant height and fresh weight, with increases of 5.87% and 93.21% respectively. Meanwhile, their MDA level, relative electrical conductivity, and accumulations of H₂O₂ and O₂⁻ were all significantly reduced, with decreases of 20.47%, 35.47%, 31.50%, and 36.78% respectively. Consistently, these data showed the same trend in calli, Arabidopsis thaliana, and tomato. These results demonstrated that the overexpression of MbACD11 significantly enhanced Zn tolerance in transgenic plants, and also verified that the function of this gene may be conserved across different species. In summary, this study establishes a molecular framework and theoretical basis for improving plant tolerance to Zn stress and paves the way for future mechanistic investigations.