Functional validation of transcription factors potentially involved in lignin and tricin metabolism in Setaria viridis

• Grant number: 25/06134-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2025
• End date: August 31, 2026
• Field of knowledge: Biological Sciences - Botany - Pant Physiology
• Principal Investigator: Igor Cesarino
• Grantee: Erika Patricia Aires Oliveira
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/06142-8 - Steering the shikimate/phenylpropanoid pathway: from gene function discovery to green factories, AP.BIOEN.JP2

Abstract

Lignin is an essential polymer of the plant cell wall, formed mainly by the monomers p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S), derived from the phenylpropanoid pathway. However, from an industrial point of view, its structural complexity hinders the access to sugars and aromatic compounds present in the cell wall that can be converted into second-generation biofuels and bioproducts. In addition to monolignols, compounds belonging to other classes of the phenolic metabolism have already been identified as authentic lignin monomers in different tissues and/or plant species. In grasses, the flavone tricin was identified as an authentic lignin monomer, influencing the structure and recalcitrance of the cell wall. However, the regulatory mechanisms that control its biosynthesis have not yet been fully elucidated. This project aims to validate 5 transcription factors (TFs) potentially involved in the regulation of tricin biosynthesis in the model grass Setaria viridis. Candidate TFs were selected using the integration of metabolomic and transcriptomic data, based on the analysis of gene coexpression and metabolite accumulation of the tricin biosynthetic pathway. The validation of these TFs will be performed by in vivo DNA-protein interaction analysis in Nicotiana benthamiana, using RUBY as a reporter. These transient expression assays will be performed to evaluate the ability of candidate TFs to activate the promoters of the SvCYP75B4 and SvCYP93G1.2 genes, which are specific to the tricin biosynthetic pathway. The identification of TFs involved in the regulation of tricin biosynthesis in S. viridis will contribute not only to fill a knowledge gap in the phenolic metabolism in grasses, but also to enhance future biotechnological strategies to reduce plant biomass recalcitrance. (AU)