Abstract:

Objective The class Ⅲ peroxidase (POD) gene family is involved in various biotic and abiotic stresses in plants. This study aimed to identify the CmPOD family genes and analyze their expression in leaf tissues under low-temperature stress to explore their response to cold stress. Method The thin-skinned melon variety ‘Tongtianmi 4’ was used as the material. Bioinformatics methods were employed to identify the melon POD gene family, and a systematic analysis was conducted on their physicochemical properties, phylogenetic tree, gene structure, and cis-acting elements. Protein structure prediction and expression analysis under low-temperature stress were performed for selected CmPOD genes. Result A total of 77 members of the CmPOD gene family were identified and named CmPOD1-1 to CmPOD12-7. The amino acid residue number ranged from 121 to 416 aa, and the pI value ranged from 4.53 to 9.50. Subcellular localization was mainly predicted in chloroplasts and the extracellular matrix. The CmPOD genes were unevenly distributed across 12 chromosomes, with 15 members each on Chr01 and Chr11. Phylogenetic analysis divided the CmPOD gene family into 13 subfamilies. The promoter regions were rich in stress-responsive cis-elements such as MYB, MYC, ABRE, and LTR. RT-qPCR results showed that after treatment at 4 ℃ for 24 h and 48 h, genes including CmPOD11-13, CmPOD12-6, and CmPOD11-14 were upregulated in leaves, while CmPOD7-3 was downregulated. Conclusion Seventy-seven members of the POD gene family were identified in melon, and their expression levels varied under low-temperature stress. It is speculated that the CmPOD gene family is involved in the response of melon to low-temperature stress.

Key words: melon, POD gene family, low-temperature stress, expression analysis, bioinformatics analysis