Genome-Wide Identification, Evolutionary Analysis, and Functional Studies of Genes in Melon ( L.).

The antioxidative enzyme ascorbate peroxidase (APX) exerts a critically important function through scavenging reactive oxygen species (ROS), alleviating oxidative damage in plants, and enhancing their tolerance to salinity. Here, we identified 28 genes that display an uneven distribution pattern throughout the 12 chromosomes of the melon genome by carrying out a bioinformatics analysis. Phylogenetic analyses revealed that the gene family comprised seven different clades, with each clade of genes exhibiting comparable motifs and structures. We cloned 28 genes to infer their encoded protein sequences; we then compared these sequences with proteins encoded by rice APX proteins (OsAPX2), APX proteins (PutAPX) and with pea APX proteins. We found that the , , and genes in Clade I were closely related, and their structures were highly conserved. () was found to promote resistance to 150 mM NaCl salt stress, according to quantitative real-time fluorescence PCR. Transcriptome data revealed that was differentially expressed among tissues, and the observed differences in expression were significant. Virus-induced gene silencing of significantly decreased salinity tolerance, and exhibited differential expression in the leaf, stem, and root tissues of melon plants. This finding demonstrates that exerts a key function in melon's tolerance to salt stress. Generally, could be a target in molecular breeding efforts aimed at improving the salt tolerance of melon; further studies of could unveil novel physiological mechanisms through which antioxidant enzymes mitigate the deleterious effects of ROS stress.