PrDA1-1 and its interacting proteins PrTCP1/PrTCP9 in flare tree peony affect yield by regulating seed weight and number

Tree peony is an emerging woody oilseed crop that has the potential to help meet the growing demand for edible oil and biofuel, and breeding high-yield varieties is the key to increasing production. The DA1 gene regulates seed weight and number and effectively improves crop yield; however, its function in tree peonies has not yet been reported. In this study, three PrDA1 genes were first identified in the whole genome of ‘Jing Hong’ flare tree peony (Paeonia rockii). PrDA1-1, which contains three types of conserved structural domains UIM (ubiquitin-interacting motif), LIM (Lin11, Isl- 1, and Mec-3), and DA-like, is homologous to AtDA1. PrDA1-1 was strongly expressed during both the early and late stages of seed development, and its constitutive expression in Arabidopsis reduced seed number but increased seed weight, which ultimately led to a decrease in yield. PrDA1-1 interacted with PrTCP1/PrTCP9 in yeast and plants, and the constitutive expression of PrTCP1/PrTCP9 in Arabidopsis increased seed weight and number, which resulted in high yield. We showed that PrDA1-1 and PrTCP1/PrTCP9 regulate seed weight and number to affect yield; these new genetic resources will help improve the seed yield of tree peonies..