Miscanthus biomass quality for conversionexploring the effect of genetic background and nutrient limitation on the cell wall

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Student thesis: Doctoral ThesisDoctor of Philosophy

Original languageEnglish
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Award date2021
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Abstract

Miscanthus is a promising dedicated biomass crop for the bio-industry. The genus includes 16 species and recently interspecific hybrids of Miscanthus with increased biomass yield have been created. However, our ability to use Miscanthus biomass for producing energy and chemicals sustainably and profitably depends on the ability to cultivate it on marginal lands and harnessing its cell wall recalcitrance. Although cell wall characteristics vary between genotypes, the full range of this variability in the genus has not been fully explored yet. We selected 49 Miscanthus genotypes, from 10 different genetic groups, according to the climate and soil conditions of their area of origin to investigate the extent of variability of cell wall characteristics across the
Miscanthus genus. We know that, besides genotypic variation, cell wall properties are also affected by abiotic stresses. However, there is little information about how nutrient limitation, typical in marginal lands, affects the cell wall composition of different Miscanthus species and their hybrids. To address this, we selected 12 genotypes from the beforementioned group, with
contrasting cell wall structure and quality for conversion, and imposed a nitrogen and phosphorous limitation during their growth for 60 days. The recalcitrance of cell wall to deconstruction was affected by the organ in a species specific manner. In general leaf material showed a lower recalcitrance to enzymatic deconstruction. Stem material compared to the leaf material had a higher xylan decoration, a lower ratio between cellulose and hemicellulose and a higher ratio between syringyl and guaiacyl monomers in the lignin. Under nitrogen and phosphorus limitation, there was a species-specific alteration of the saccharification efficiency and the carbohydrate profile of the cell wall.
The outcomes of this work increased our knowledge about cell wall composition in the genus Miscanthus and the effect of specific nutrient stress on cell wall composition and recalcitrance. A future for the Miscanthus biomass crop can be envisioned where specific nutrient limitation can be used as a treatment to direct the quality of the biomass for conversion