ARF4 acting upstream of LBD16 promotes adventitious root formation in peach

Although class A auxin response factors(ARFs) are known to regulate adventitious root(AR) development through the canonical SCFTIR1-Aux/IAA-ARF signaling pathway, the regulatory role of class B ARFs in AR development remains largely unclear. Therefore, this research focused on the role of class B ARF transcription factors in peach(Prunus persica ‘Shengli') adventitious root formation. Here, we report the role of a class B ARF gene Pp ARF4 in adventitious root formation in peach. Comparative transcriptome and q RT-PCR analyses showed that the transcription of Pp ARF4 was significantly up-regulated in auxin-treated stem explants. Y2H assay showed that Pp ARF4 had no interaction with Pp IAAs(AUXIN/INDOLE ACETIC ACIDs). Pp ARF4 could bind the promoters of lateral root development gene Pp LBD16 and auxin transport gene Pp PIN1 to activate their transcription. Ectopic overexpression of Pp ARF4 and Pp LBD16 in Arabidopsis promoted AR development. Additionally,Pp ARF4 could act as a negative regulator of flavone synthesis and thus prevent the explants from browning. The results not only provide novel insights into the functions of ARFs in regulating plant growth and development, but will also be useful for fulfilling asexual propagation by stem cuttings in peach.