Climate change affects cell‐wall structure and hydrolytic performance of a perennial grass as an energy crop

Abstract

Perennial grasses, such as Panicum maximum, are important alternatives to dedicated energy crops for bioethanol production. This study investigates whether future climate conditions could influence P. maximum cell-wall structure and hydrolytic performance. To analyze interactions with environmental factors in field conditions, a combined Free-air Temperature and CO 2 Controlled Enhancement (Trop-T-FACE) facility was used to investigate the isolated and combined effect of elevated atmospheric CO 2 concentration (eC) (600 μmol.mol −1 ) and elevated temperature (eT) by 2 °C more than the ambient temperature, on cell-wall composition, cellulose crystallinity, accessibility, and hydrolysis yields. The elevated temperature treatments (eT and eT + eC) exhibited the most pronounced effects on the P. maximum cell wall. Warming reduced the starch content and the crystallinity index (CI) of cellulose and increased the cellulose content. Fluorescent protein-tagged carbohydrate-binding modules analysis demonstrated that warming improved total cellulose surface exposure/accessibility in eT and eT + eC

Challenges of Biomass Utilization for Bioenergy in a Climate Change Scenario

“…In the non-cellulosic fraction of cell wall, the substitution of arabinose in the xylose backbone, indicated by the xylose: arabinose ratio was reduced for Guinea grass and coffee leaves under heat regardless of the CO 2 concentration [ 135 , 136 ]. In contrast, in wheat grain arabinose substitution degree increased under heat stress [ 137 ].…”

“…In contrast, an increase in levels of sinapic acid, phenylalanine, and α-Tocopherol were found under warming conditions, which was pointed to impact lignin composition by increasing the content of S-type units [ 34 ]. Freitas et al (2020) [ 136 ] proved it, in which Guinea grass under elevated temperature conditions (warmed by 2 °C above current temperature) presented higher S lignin and S/G ratios, demonstrating a positive effect of temperature for hydrolysis since S lignin is described to easily hydrolyze upon pretreatment step. In Eucalyptus , drought stress disrupted lignin deposition in leaves and increased the S/G unit ratio [ 141 ].…”

“…A previous work of our group applied Carbohydrate-Binding Module (CBMs) to study the effect of climate change on the accessibility of cell wall polysaccharides to hydrolytic enzymes. We found that the higher percent glucan composition, S/G ratio, higher xylose: arabinose ratio found for Guinea grass developed under warming resulted in higher surface accessibility of cellulose and xylan, enhancing the sugar yields after biomass enzymatic hydrolysis [ 136 ].…”