The Ibmyb52/Ibarf11l-Ibdrm1 Module Negatively Regulates the Root Development of Sweetpotato

Abstract

The formation and development of sweetpotato (Ipomoea batatas (L.) Lam) storage roots directly affect its yield and quality. This process involves multidimensional interaction of genetic regulation, hormone signal transduction, environmental response, and cultivation management. Natural auxin indole-3-acetic acid (IAA) is closely associated with the formation and tuber roots development of sweetpotato. Previously, we select the IbDRM1 gene that was strongly upregulated in its progeny crossing with “Meiguohong” named “Xu18-192” (X192) exhibits significant delay in root expansion but 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 roots development of sweetpotato, causing decreased yield. Meanwhile, the IAA content was reduced throughout the growth period while the RNA interference (Ri) lines was opposite. Furthermore, RT-qPCR analysis demonstrated that the expressions of the key genes involved in the IAA signaling pathway and roots development were down-regulated in overexpressing (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%. Correspondingly, the roots development of the IbMYB52 OE plants was also significantly inhibited. The auxin response factor IbARF11L interacts with IbMYB52 to enhance the transcription of IbDRM1 gene. This study elucidates the molecular mechanism by which the IbMYB52/IbARF11L-IbDRM1 module negatively regulates the roots development of sweetpotato, offering potential key genes for genetic breeding to improve roots development.

Keywords: Sweetpotato, IbDRM1, Roots development, IbMYB52, IbARF11L, Auxin