An Arabidopsis NAC domain transcriptional activator VND7 negatively regulates <i>VNI2</i> expression

Abstract

A NAC domain transcription factor, VND-INTERACTING2 (VNI2) is originally isolated as an interacting protein with another NAC domain transcription factor, VASCULAR-RELATED NAC-DOMAIN7 (VND7), a master regulator of xylem vessel element differentiation. VND7 directly or indirectly induces expression of a number of genes associated with xylem vessel element differentiation, while VNI2 inhibits the transcriptional activation activities of VND7 by forming a protein complex. VNI2 is expressed at an earlier stage of xylem vessel element differentiation than VND7.Here, to investigate whether VND7 also affects VNI2, a transient expression assay was performed. We demonstrated that VND7 downregulated VNI2 expression. Other transcription factors involved in xylem vessel formation did not show the negative regulation of VNI2 expression. Rather, MYB83, a downstream target of VND7, upregulated VNI2 expression. By using the deletion series of the VNI2 promoter, a 400 bp region was identified as being responsible for downregulation by VND7. These data suggested that VND7 and VNI2 mutually regulate each other, and VNI2 expression is both positively and negatively regulated in the transcriptional cascade.

NAC domain transcription factors VNI2 and ATAF2 form protein complexes and regulate leaf senescence

“…Recently, we have shown that VND7 negatively regulates VNI2 expression (Ailizati et al, 2021 ). By contrast, ATAF2 upregulates VNI2 gene expression (Nagahage et al, 2020 ).…”

VND-INTERACTING2 effectively inhibits transcriptional activities of VASCULAR-RELATED NAC-DOMAIN7 through a conserved sequence

“…It is also interesting to note the relationship among VNI2 and XND1. Recently, we have shown that VND7 downregulates VNI2 gene expression (Ailizati et al 2021). Thus, it is possible that the NAC domain transcription factors may mutually regulate each other during xylem vessel element differentiation.…”

“…The effector, reporter, and reference plasmids were used to transfect protoplasts obtained from 3 to 4-week-old Arabidopsis leaves, according to a previously reported PEG transformation method (Sakamoto et al 2016). Luciferase activity was measured as described by Ailizati et al (2021). More than four biological replicates were used, and the experiment was repeated at least more than two times.…”

Current Understanding of the Genetics and Molecular Mechanisms Regulating Wood Formation in Plants

“…Expression of C-terminal truncated VND-INTERACTING2 ( VNI2 ) under the control of the VND7 promoter resulted in inhibition of xylem vessel development in Arabidopsis roots and aerial organs [ 68 ]. Recently, the authors of [ 69 ] demonstrated that VND7 downregulated VNI2 expression and that MYB83, a downstream target of VND7, upregulated VNI2 expression.…”