Determination of lignin content in stems of different varieties of sugarcane

Abstract

The recalcitrance of the cell wall is associated with the presence of lignin in plant tissues, hindering and making more costly the use of biomass for second generation ethanol production. This is a major obstacle in the sucro-energetic industry, since the high concentration of lignin in the cell wall is directly related to the speed and extraction intensity of the substrate for production as well as in the degradation of biomass.Previous studies from our group with four varieties of sugarcane (RB72454, RB855156, RB867515 and RB92579) indicated differences in soluble sugar content, which may be related to the production of first generation ethanol. Beyond it was also found differences in the metabolic profile among the varieties as well as in portions of the evaluated stem parts. Among the differences are the levels of shikimic acid, a precursor for synthesis of phenolic compounds and, ultimately, the lignin.Following the studies on comparative characterization of varieties of sugarcane with higher potential in the sugarcane industry, is of great importance the biochemical investigation of these varieties aiming at both first and second generation ethanol.Considering the recalcitrance of the cell wall by the presence of lignin can be an obstacle in production of second generation ethanol, we will test the following assumptions: i) the variations found in the shikimic acid concentration in the different varieties and sugarcane portions reflect changes in lignin content; ii) changes in the metabolic profile are correlated to changes in lignin levels.This work is part of the JP FAPESP project entitled "Change in carbon balance in grasses in order to increase sugar production" (2012 / 23838-7), which aims at the understanding of mechanisms of control of the respiratory metabolism and carbon flux in plants. Although the idea has not been considered initially, this project will contribute to a systemic vision of carbon use in sugarcane.