Engineering the sugarcane cell wall to increase saccharification

• Grant number: 21/06567-9
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: January 01, 2022
• End date: February 28, 2025
• Field of knowledge: Biological Sciences - Genetics - Plant Genetics
• Principal Investigator: Marcelo Menossi Teixeira
• Grantee: Willian de Souza Bernardes
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 14/50884-5 - INCT 2014: National Institute of Science and Technology of Bioethanol, AP.TEM

Abstract

Sugarcane biomass is rich in complex carbohydrates that can be extracted and used to produce second-generation ethanol (2G). However, due to a complex interaction between xylans, lignin and cellulose, physical and chemical pretreatments must be used, increasing production costs and generating residues that inhibit saccharification and fermentation. The knowledge on the sugarcane cell wall is essential to develop biotechnological strategies to reduce this recalcitrance. Xylan is the main polymer adhered to cellulose microfibrils, also interacting directly with lignin. These interactions are mediated by arabinofuranose (Araf), glucuronic acid (GlcA), which are added to the xylan backbone during its biosynthesis, by xylan arabinosyltransferases (XAT) and xylan glucuronyltransferases (GUX), respectively. Sugarcane has seven genes encoding XAT homologs to those found in wheat and rice. We will silence selected sugarcane XAT genes aiming to improve the saccharification of its biomass. The biomass of Arabidopsis silenced for AtGUX1 and AtGUX2 genes is more susceptible to enzymatic hydrolysis even without pretreatments, requiring less enzymes during saccharification. We found that sugarcane silenced for ScGUX2 (homolog to AtGUX2) has increased saccharification. In view of these findings, the present project proposes to produce silenced sugarcane plants for ScXATs, ScGUX1 (homolog to AtGUX1) and a double silencing of ScGUX1 and 2 to evaluate how the cell wall and levels of saccharification are affected. In the long run, this work has the potential to develop a high-yielding sugarcane cultivar in the production of 2G ethanol.