Regulatory roles of R2R3-MYB genes in plant growth, development and stress adaptation: insights into seed dormancy and germination.

Authors

Angel J Matilla, Javier Fuertes-Aguilar

Published in

Planta. Volume 264. Issue 2. Jul 04, 2026. Epub Jul 04, 2026.

Abstract

GAMYBsand TT2 are R2R3-MYB TFs involved in seed dormancy and germination, with GAMYBs mediating GA signaling and TT2 regulating seed-coat proanthocyanidins. The MYB (v-myb avian myeloblastosis viral oncogene homolog) transcription factors (TFs) constitute one of the most diverse and evolutionarily conserved families of plant regulatory proteins, contributing to vegetative reproduction, anthocyanine (ANC) and triterpenoids biosynthesis, abiotic stress responses, immunity process and plant diversification. MYB proteins are ancient regulators, originating approximately one billion years ago in early eukaryotes and subsequently diversifying in plants and animals. The expansion of MYB genes in plants underlies their key role in generating phenotypic variation. Among the existing MYB TFs, the R2R3-MYB subfamily has undergone extensive expansion and diversification in land plants, conferring broad regulatory versatility across developmental, metabolic, and stress-response processes. Collectively, R2R3-MYB TFs are closely linked to phytohormone signalling and play a central role in fine-tuning of plant response networks. Additionally, R2R3-MYB and GAMYB TFs play central and multifaceted roles in regulating seed development, seed-coat pigmentation, dormancy, and germination. Members of the R2R3-MYB, such as MYB56, MYB62, MYB96, and MYB30, and GAMYB-related TFs highlighted here, integrate hormonal cues (ABA, GA, JAs, and NO) with transcriptional networks governing flavonoid biosynthesis, seed size determination, reserve mobilization, and seed-coat architecture. Through transcriptional and post-translational regulation, these TFs balance dormancy maintenance and germination competence. The regulatory roles of R2R3-MYB and GAMYB TFs during the final phase of the seed life cycle (SLC) are reviewed, as this topic has received little attention to date. Notably, this review synthesizes recent advances on the structural, evolutionary, and functional roles of GAMYB and TT2 TFs, including a phylogenetic analysis that highlights lineage-specific gene ascription, conserved clades, and evolutionary relationships within the R2R3-MYB family. Finally, perspectives and challenges are summarized to inform future studies on these important TFs in seed dormancy and germination.

PMID:
42401753
Bibliographic data and abstract were imported from PubMed on 05 Jul 2026.

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