Straw digestibility in rice: Novel insights from pyrolysis GC-MS and biomass phenotyping

Valorizing rice straw could mitigate the detrimental health and environmental consequences of disposal through field burning. An essential step for achieving this is reducing straw recalcitrance to digestion by either enzymes or animals to facilitate uses as fertilizer, animal feed, or conversion into fuels and chemicals. In the present work, we developed and characterized a Philippine rice diversity panel to explore the chemical basis of biomass recalcitrance. We used high throughput phenotyping of straw samples from the panel to identify chemical compounds that confer recalcitrance. We determined the saccharification potential, silica, ferulic, and p-coumaric acid content in each rice accession, as well as the chemical fingerprint of biomass composition using pyrolysis followed by GC/MS. Multivariate analysis of the phenotypic data allowed us to characterize the relationship between biomass components and straw saccharification establishing that Si, ferulic acid and coumaric acid are inversely correlated with saccharification. PCA analysis showed that pyrolysis products derived from lignin constitute the largest proportion of compounds inversely correlated with saccharification.