The MYB gene family is significant in plants, playing a role in numerous plant development processes, including metabolism, hormone signal transduction, cell identity, and biotic and abiotic stresses. Due to the recent availability of the Melastoma candidum genome, this is the first time that the MYB gene family has been identified in this species. This study identified 421 MYB gene members in the M. candidum genome using the HMMER search and BLASTp method. These MYBs were further divided into 10 sub-types, including R2R3, R-R, CPC-like, CCA1-like, TBP-like, R1R2R3, I-box, atypical MYB, MYB-CC, and MYB-like. Domain and conservation analyses revealed that each type of MYB was characterized by a different number and combination of SANTs/myb DNA-binding domains. Collinearity analysis revealed several gene duplication events within the MYB gene family. The Ka to Ks ratio suggested that most of the MYB genes underwent purifying selection during the evolution process. Phylogenetic analysis among three species confirmed our findings and displayed the evolutionary relationship of MYB genes in different species. RNA-seq of three developmental stages of flowers and WGCNA analysis identified McMYB113h, McMYB21b, and McGLK1c as playing a pivotal role during flower development in M. candidum. Finally, we conducted qRT-PCR experiments for 20 flower-development-related MYBs across 9 tissues to illustrate their expression patterns in M. candidum. This study establishes a foundation for exploring MYB gene resources and their potential applications in related industries of M. candidum.

The genus Chaenomeles has long been considered as an important ornamental, herbal and cash plant and widely cultivated in East Asian. Traditional researches of Chaenomeles mainly focus on evolutionary relationships on phenotypic level. In this study, we conducted RNA-seq for 10 Chaenomeles germplasms supplemented with one related species Docynia delavayi (D. delavay) by Illumina HiSeq2500 platform. After de novo assemblies, we have generated unigenes for each germplasm with numbers from 40 084 to 48 487. By pairwise comparison of the orthologous sequences, 9 659 othologus within the 11 germplasms were obtained, with 6 154 othologous genes identified as single-copy genes. The phylogenetic tree was visualized to reveal evolutionary relationship for these 11 germplasms. GO and KEGG analyses were performed for these common single-copy genes to compare the functional similarities and differences. Selective pressure analysis based on 6 154 common single-copy genes reveals that 45 genes were under positive pressure selection. Most of them involved in plant disease defense system building process. 292 genes containing simple sequence repeats (SSRs) were used to develop SSR markers and compare their function in secondary metabolism pathways. Finally, 10 primers were chosen as SSR markers candidates for Chaenomeles germplasms by comprehensive screening. Our research provides new methodology and reference for future related research in Chaemomeles and is also useful for improvement, breeding and selection project in other related species.