Analysis of a Modern Hybrid and an Ancient Sugarcane Implicates a Complex Interplay of Factors in Affecting Recalcitrance to Cellulosic Ethanol Production

• Published in: PloS one Vol. 10; no. 8; p. e0134964
• Main Authors: Guzzo de Carli Poelking, Viviane, Giordano, Andrea, Ricci-Silva, Maria Esther, Rhys Williams, Thomas Christopher, Alves Peçanha, Diego, Contin Ventrella, Marília, Rencoret, Jorge, Ralph, John, Pereira Barbosa, Márcio Henrique, Loureiro, Marcelo
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07-08-2015; Public Library of Science (PLoS)
• Subjects: Acids; Alternative energy sources; BASIC BIOLOGICAL SCIENCES; Biochemistry; Biomass; Biomass energy; Biosynthesis; Biotechnology - methods; Carbohydrate Metabolism; Cell Wall - metabolism; Cell walls; Cellulose; Cellulose - metabolism; Cellulose esters; Composition; Correlation analysis; Developmental stages; Esterification; esters; Ethanol; Ethanol - metabolism; Fermentation; G ratio; Genotype; Genotypes; Grasses; Hybridization, Genetic; Hydrolysis; internodes; Lignin; Lignin - metabolism; Magnetic Resonance Spectroscopy; phenols; plant cell walls; Plant morphology; Plant Stems - growth & development; Saccharification; Saccharum - anatomy & histology; Saccharum - genetics; Saccharum - growth & development; Saccharum officinarum; Saccharum spontaneum; Sugarcane; Uronic Acids - metabolism; Xylans - metabolism; United States; Brazil; New York; United States > US; Wisconsin
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0134964

Abundant evidence exists to support a role for lignin as an important element in biomass recalcitrance. However, several independent studies have also shown that factors apart from lignin are also relevant and overall, the relative importance of different recalcitrance traits remains in dispute. In this study we used two genetically distant sugarcane genotypes, and performed a correlational study with the variation in anatomical parameters, cell wall composition, and recalcitrance factors between these genotypes. In addition we also tracked alterations in these characteristics in internodes at different stages of development. Significant differences in the development of the culm between the genotypes were associated with clear differential distributions of lignin content and composition that were not correlated with saccharification and fermentation yield. Given the strong influence of the environment on lignin content and composition, we hypothesized that sampling within a single plant could allow us to more easily interpret recalcitrance and changes in lignin biosynthesis than analysing variations between different genotypes with extensive changes in plant morphology and culm anatomy. The syringyl/guaiacyl (S/G) ratio was higher in the oldest internode of the modern genotype, but S/G ratio was not correlated with enzymatic hydrolysis yield nor fermentation efficiency. Curiously we observed a strong positive correlation between ferulate ester level and cellulose conversion efficiency. Together, these data support the hypothesis that biomass enzymatic hydrolysis recalcitrance is governed by a quantitative heritage rather than a single trait.