The IbMYB52/IbARF11L-IbDRM1 module negatively regulates the root development of sweetpotato

The formation and development of sweetpotato (Ipomoea batatas (L.) Lam) storage roots directly affect its yield and quality. This process involves a multidimensional interaction of genetic regulation, signal transduction of hormones, environmental response, and cultivation management are all interconnected. The natural auxin indole-3-acetic acid (IAA) plays a crucial role in the formation and root development of sweetpotatoes. Previously, we selected the IbDRM1 gene that was strongly upregulated in its progeny crossing with "Meiguohong" named "Xu18-192" (X192) exhibits a significant delay in root expansion but the lower expression in sweetpotato variety "Xuzishu8" (XZ8) exhibits normal roots development. IbDRM1 contains a conserved Auxin-repressed domain and is significantly induced by IAA. Compared with the wild-type (WT), overexpression of the IbDRM1 gene inhibits root development and reduces sweetpotato yield, accompanied by decreased IAA content throughout the growth period, whereas RNA interference (Ri) lines exhibit opposite effects. Furthermore, RT-qPCR analysis revealed that the expression levels of key genes involved in the IAA signaling pathway and root development were reduced in overexpression (OE) plants. Further analysis revealed that IbMYB52 could directly bind to the IbDRM1 promoter and promote its expression. The IAA content of IbMYB52 OE plants increased by 14.04 %-23.53 %. Similarly, root development in IbMYB52 OE plants was notably inhibited. The auxin response factor IbARF11L interacts with IbMYB52 to enhance the transcription of IbDRM1. This study elucidates the molecular mechanism by which the IbMYB52/IbARF11L-IbDRM1 module negatively regulates the root development of sweetpotato, offering potential key genes for genetic breeding to improve root development.