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

Abstract

An Arabidopsis NAC domain transcription factor VND-INTERACTING2 (VNI2) was 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. VNI2 inhibits transcriptional activation activity of VND7 by forming a protein complex. Here, to obtain insights into how VNI2 regulates VND7, we tried to identify the amino acid region of VNI2 required for inhibition of VND7. VNI2 has an amino acid sequence similar to the ETHYLENE-RESPONSIVE ELEMENT BINDING FACTOR (ERF)-associated amphiphilic repression (EAR) motif, conserved in transcriptional repressors, at the C-terminus. A transient expression assay showed that the EAR-like motif of VNI2 was not required for inhibition of VND7. The C-terminal deletion series of VNI2 revealed that 10 amino acid residues, highly conserved in the VNI2 orthologs contributed to effective repression of the transcriptional activation activity of VND7. Observation of transgenic plants ectopically expressing VNI2 showed that the identified 10 amino acid sequence strongly affected xylem vessel formation and plant growth. These data indicated that the 10 amino acid sequence of VNI2 has an important role in its transcriptional repression activity and negative regulation of xylem vessel formation.

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

“…In addition, other NAC domain transcription factors, VND‐INTERACTING1 (VNI1), VNI2, and ANAC103, were isolated as interacting proteins with VND7 (Yamaguchi et al, 2015 ; Yamaguchi, Ohtani, et al, 2010 ). Further analyses showed that VNI2 inhibits the transcriptional activation activities of VND7 by forming protein complexes, negatively regulating xylem vessel formation (Ailizati et al, 2022 ; Yamaguchi, Ohtani, et al, 2010 ).…”