Genome-wide identification and characterization of apple long-chain Acyl-CoA synthetases and expression analysis under different stresses.

Long-chain acyl-CoA synthetases (LACSs) are members of the acyl-activating enzyme superfamily that have important roles in lipid synthesis and storage, fatty acid catabolism, vectorial acylation, and synthesis of cutin and wax. Here, 11 apple MdLACS genes were identified based on the Malus × domestica reference genome, clustered into six groups and mapped to ten chromosomes. Multiple sequence alignment and conserved motifs analyses showed that the sequences of the AtLACS and MdLACS proteins were highly conserved. A cis-element analysis in the promoter regions of the MdLACS genes revealed various elements related to stress responsiveness and plant hormones. Subsequently, expression analysis demonstrated that the MdLACS genes had different expression profiles in different tissues in response to various abiotic stresses. To further study the function of MdLACS genes in apple, MdLACS1 was isolated to identify its basic function, which the function of MdLACS1 in response to apple abiotic stress resistance was determined by the transgenic method. The results showed the MdLACS1 enhanced tolerance to polyethylene glycol, salt, and abscisic acid in the apple callus, suggesting that MdLACS1 is an important regulator in response to abiotic stresses. Finally, the functional interoperability network among the MdLACS proteins was predicted and analyzed, which could the understanding of the possible interactions among proteins and genes regulatory networks concerned with wax biosynthesis and regulatory mechanisms in response to abiotic stresses in apple.