Transcriptome and metabolome analysis reveals the potential mechanism of tuber dynamic development in yam (Dioscorea polystachya Turcz.)

Yam (Dioscorea spp.) is a multispecies and multipurpose tuber crop. To clarify the mechanism of tuber development, we performed a time-course phenotypic, cytological, physiological, metabolomic, and transcriptomic analysis of yam tubers. The results showed that the tuber weight increased with the accumulation of starch, and sucrose metabolism was also active during tuber development. Meanwhile, abscisic acid (ABA) levels were positively correlated with tuber weight, while gibberellin (GA) was negatively. Metabonomic analysis showed that 400 metabolites accumulated during tuber development, which played an important role in the regulation of tuber growth and development, flavor and medicinal ingredients. A total of 743 differentially expressed genes (DEGs) were assigned to 21 KEGG pathways such as starch and sucrose metabolism, plant hormone signal transduction pathway and flavonoid pathway by comparative transcriptome. Comprehensive transcriptome and metabolome analysis revealed the DEGs and differentially accumulated metabolites (DAMs) of plant hormone signal transduction pathway, starch and sucrose metabolism, and flavonoid synthesis pathway. In conclusion, the DAMs and DEGs involved in plant hormone signal transduction pathway, starch and sucrose metabolism pathway and flavonoid metabolism pathway play an important role in the regulation of tuber development. This study provides theoretical basis and practical guidance in molecular breeding and quality improvement of yam.