This study investigates the transcriptional regulation of xylem vessel formation in plants, focusing on the roles of VASCULAR-RELATED NAC-DOMAIN6 (VND6) and VND7. Microarray analysis and promoter analysis revealed that VND6 and VND7 are involved in the transcriptional regulation of xylem vessel formation. Overexpression of VND6 and VND7 in Arabidopsis and poplar led to the transdifferentiation of various cell types into metaxylem and protoxylem-like vessel elements, respectively. Dominant repression of VND6 and VND7 specifically inhibited metaxylem and protoxylem vessel formation in roots, respectively. The findings suggest that VND6 and VND7 act as transcription switches for metaxylem and protoxylem vessel formation, respectively. The study also explored the subcellular location and hormone effects of VND6 and VND7, providing insights into their regulatory mechanisms.This study investigates the transcriptional regulation of xylem vessel formation in plants, focusing on the roles of VASCULAR-RELATED NAC-DOMAIN6 (VND6) and VND7. Microarray analysis and promoter analysis revealed that VND6 and VND7 are involved in the transcriptional regulation of xylem vessel formation. Overexpression of VND6 and VND7 in Arabidopsis and poplar led to the transdifferentiation of various cell types into metaxylem and protoxylem-like vessel elements, respectively. Dominant repression of VND6 and VND7 specifically inhibited metaxylem and protoxylem vessel formation in roots, respectively. The findings suggest that VND6 and VND7 act as transcription switches for metaxylem and protoxylem vessel formation, respectively. The study also explored the subcellular location and hormone effects of VND6 and VND7, providing insights into their regulatory mechanisms.