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Going deep into the phenylpropanoid metabolism in C4 grasses using Setaria viridis as model species

Grant number: 19/25587-0
Support type:Regular Research Grants
Duration: February 01, 2021 - January 31, 2024
Field of knowledge:Biological Sciences - Botany - Pant Physiology
Cooperation agreement: Max Planck Society for the Advancement of Science
Principal researcher:Igor Cesarino
Grantee:Igor Cesarino
Principal researcher abroad: Alisdair R. Fernie
Institution abroad: Max Planck Society, Potsdam, Germany
Home Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Plant biomass, which is mostly composed of polysaccharide-rich secondary cell walls, constitutes a promising source of fermentable sugars for the production of biofuels and biomaterials. However, the presence of the phenolic polymer lignin largely precludes the release of monosaccharides during enzymatic hydrolysis of these cell wall polysaccharides in the biorefinery. Therefore, unraveling the molecular mechanisms underlying the phenylpropanoid metabolism and, thus, lignin metabolism is essential for unlocking the economic potential of lignocellulosic biomass. In the context of the bioeconomy, C4 grasses emerge as prominent lignocellulosic feedstocks due to their high biomass yield ensured by C4 photosynthesis. However, our understanding of many aspects of the lignin metabolism, such as regulation, biosynthesis and polymerization, remains fragmentary, especially when compared to eudicot species. Moreover, several grass-specific features of the phenylpropanoid metabolism cannot be extrapolated from data obtained with eudicot model plants. In this project, we aim to broaden our knowledge on the phenylpropanoid and lignin metabolisms in C4 grasses by applying a systems biology approach using Setaria viridis as model species. First, a deep systems characterization of different S. viridis tissues will be performed using metabolomics (employing mass spectrometry-based techniques) and transcriptomics (employing RNAseq) to generate comprehensive molecular data to build a Setaria viridis eFP (electronic fluorescent pictographs) browser. This tool allows the visualization of molecular data (e.g. gene expression patterns, metabolite accumulation) in different plant tissues in a user-friendly interface, which might be very useful for the scientific community to initially infer gene functions. Secondly, top candidate genes that are co-expressed with lignin biosynthetic genes in large-scale transcriptomics databases of grasses (previously generated in the scope of a Fapesp Young Investigator Awards Project, Processo n° 2015/02527-1) will be functionally characterized in S. viridis. These genes have been already selected and their initial characterization has been performed. These genes will be further misregulated in plant and the resulting transgenic lines will be deeply characterized for i) biomass parameters, ii) metabolite profiling, iii) lignin deposition, iv) global gene expression; and v) saccharification yield. Therefore, the misregulation of such genes will be used as a strategy to both elucidate novel aspects of the phenylpropanoid/lignin metabolism in C4 grasses and to validate novel biotechnological strategies to improve biomass processing in the biorefinery. (AU)