Genome-Wide Characterization of Genes in Yam () Reveals Their Potential Roles in Tuber Expansion and the Gibberellin Response.

Yam ( spp.) provides various nutritional and medicinal benefits, including a high starch content, dietary fiber, essential micronutrients, and bioactive compounds. The molecular mechanisms underlying tuber expansion have not yet been clarified. Rapid alkalinization factor () genes, which mediate various processes in plants, are thought to contribute to the regulation of tuber growth; however, their role in yam development, especially in gibberellin (GA)-mediated processes, remains unclear. Here, we characterized seven genes in the yam genome. Analysis of gene duplication demonstrated that the expansion of genes was primarily driven by whole-genome duplication or segmental duplication. Phylogenetic analysis revealed that genes were concentrated in specific clusters, indicating that their functions are relatively conserved. was specifically expressed in the roots, and , , , and were highly expressed in flowers. , , , , , and were shown to play a role in tuber expansion. Subsequent qRT-PCR validation of four selected genes confirmed the regulation of , , , and by GA and PP333 (paclobutrazol, a GA biosynthesis inhibitor). Yeast one-hybrid assays further showed that the promoter region interacted with the GA-signaling protein, DrDELLA1. Our findings provide novel insights into the regulatory network controlling yam tuber expansion, especially through the interaction between and GA signaling pathways. Our results clarify the molecular mechanisms involved in tuber growth and propose a promising strategy for improving yam production through genetic manipulation of the GA-RALF signaling pathway.