Genome-wide Identification and Characteristics Analysis of Melon ( Cucumis melo L.) MYB Transcription Factors and Their Responses to Autotoxicity and Saline-alkali Stress

MYB transcription factors, one of the largest gene families in plants, play an important role in plant stress response. In this paper, MYBs of melon were identified and classified by genome wide analysis, and their physicochemical properties, structural characteristics and phylogenetic relationships were analyzed. The response of melon MYB to autotoxicity and saline-alkali stress was analyzed by using transcriptome sequencing database and RT-qPCR. A total of 178 MYB s was identified from melon genome database, which can be divided into four subfamilies, of which 81 belong to 1R-MYB subfamily and 95 belong to R2R3-MYB subfamily. 2R-MYB subfamily is more conservative than 1R-MYB subfamily. Most MYB were located in the nucleus. Only a few members were located in chloroplast, cytoplasm, plastid and mitochondria. MYBs were distributed on all 12 chromosomes of melon, with 27 on chromosome 4 and 6 on chromosome 10. All of the 12 chromosomes contained duplicated MYB genes, whereas chromosomes 4 contained the highest number, 10. Tandem and fragment duplication play an important role in the evolution of melon MYB genes. The Cis-acting element of melon MYB contain three types of response elements: defense and stress response elements (DSREs), light response elements (LREs) and hormone response elements (HREs). 60 melon MYBs were differentially expressed under autotoxicity, 6 were involved in saline alkali response, CmMYB2R40 and CmMYB2R54 were both responsive to autotoxicity and saline-alkali stress. MYBs , which involved in the response of melon autotoxicity and saline-alkali stress, were closely related to osmotic regulation, stomatal on–off, and autotoxicity chemicals synthesis. The results of this paper will contribute to the comprehensive understanding of the characteristics of MYBs in melon and its potential role in stress resistance.