Abstract
We have been analyzing mechanisms of vascular development in plants using Zinnia in vitro culture system for transdifferentiation from mesophyll cells to tracheary elements. Using the cDNA microarray, we found many genes with up-regulated expression in the middle phase of transdifferentiation, among which the gene (Z567) encoding a NAC-domain protein was included. In this study, we carried out functional analysis of Arabidopsis genes with the similarity to Z567. We searched the Arabidopsis genome and selected 7 Arabidopsis genes, VND (Vascular related NAC-Domain protein) 1 to 7, respectively. Promoter analysis in Arabidopsis roots revealed that VND1 to VND4 were expressed in the vascular bundle and VND5 and VND7 were expressed in immature vessels. Furthermore, we found that overexpression of VND7 resulted in ectopic xylem vessel formation from cortex cells in root. These results strongly suggest that VND7 gene is a positive regulator of vessel formation in plants.
