# Expanded functional roles of R2R3-MYB (S6) transcription factors in balancing phenylpropanoid and phenolamide pathways in Solanaceae

## TL;DR

This study explores how two related R2R3-MYB genes in plants influence pigmentation and vascular development by regulating specific biochemical pathways.

## Contribution

The study reveals distinct functional roles of AN1 and AN2 R2R3-MYB genes in regulating phenylpropanoid and phenolamide pathways in Solanaceae.

## Key findings

- AN1 and AN2 differentially affect plant pigmentation and vascular tissue structure.
- Both genes promote phenolamide accumulation, but AN1 more strongly regulates the phenylpropanoid pathway.
- AN2 may play a role in vascular development, suggested by GUS promoter localization.

## Abstract

Events of duplication and neo/subfunctionalization have significantly expanded the functional roles of R2R3 myeloblastosis (MYB) transcription factors in plants. In a previous study, we demonstrated that two paralogous R2R3 MYBs from Solanum tuberosum and S. commersonii, AN1 and AN2, respectively, induce anthocyanin pigmentation to varying extents when transiently overexpressed. However, questions related to the distinct functions of these genes remained unanswered. In this study, we further investigated these genes by comparing transgenic tobacco plants that constitutively overexpress AN1 and AN2. We observed differences between AN1 and AN2 that not only influenced plant pigmentation but also impacted the structural features of vascular tissues. Both genes promoted the accumulation of phenolamides; however, AN1 showed a stronger capacity to regulate the phenylpropanoid pathway. In addition, our results suggest a potential role for AN2 in regulating additional biological processes potentially involved in vascular development, as indicated by the GUS promoter localization study. Collectively, these results shed new light on the potentially ancestral functions of these R2R3 MYB genes, extending their known impact beyond anthocyanin biosynthesis.