Identification and analysis of the expansin gene family in yam

Expansins are a group of proteins that loosen plant cell walls and cellulose materials and are involved in regulating plant cell growth and diverse developmental processes. However, a systematic study of the Dioscorea opposita expansin (DoEXP) gene family has not yet been conducted. In this study, we used publicly available genomic data from yam to identify members of the DoEXP gene family and analyse its physicochemical properties, phylogeny and expression pattern using bioinformatics software. Thirty EXP genes were identified from the yam genome and can be classified into four subfamilies, DoEXPA, DoEXPB, DoEXLA, and DoEXLB, which are distributed across 14 chromosomes. All EXP proteins contain two conserved structural domains (DPBB_1 and expansin_C) and have highly similar motif compositions and exon-intron structures. Examination of the promoter regions of these genes revealed the presence of cis-acting elements associated with growth and development, phytohormone signaling, and abiotic stress. The collinearity analysis revealed that segmental duplication is the primary cause of the expansion of the DoEXP gene family. Gene Ontology (GO) enrichment analysis revealed that DoEXP genes (DoEXPs) are significantly associated with root elongation and cell differentiation processes. Utilizing quantitative real-time polymerase chain reaction (qPCR), the expression patterns of nine selected DoEXPs were validated. The results of this study are helpful for understanding the molecular functions of expansin proteins in yam tuber expansion and provide a theoretical basis for revealing the molecular regulatory mechanism of yam tuber growth and development.