Toward bioeconomy of a multipurpose cereal: Cell wall chemistry of Sorghum is largely buffered against stem sugar content

Abstract

Background and Objectives: Sorghum (Sorghum bicolor L. Moench) is a multipurpose crop with high potential for the bioeconomy. Ten sweet, grain and dual-purpose sorghum genotypes were compared with respect to sugar-related traits and cell wall composition. Findings: The dual-purpose hybrids Ganymed, Zerberus, and Tarzan performed better with respect to plant height, cane weight, and juice volume, but the sweet genotype KIT1 produced the highest sugar concentration (°Brix) in the stem. Analytical sugar data demonstrate genotypic differences in terms of sugar composition and concentrations, with sucrose being dominant. The monosaccharide composition of the stem cell wall polysaccharides showed surprisingly little genotypic variability. Variations in contents of lignin and cell wall-bound hydroxycinnamate monomers were moderate. Conclusions: Sweet, grain and dual-purpose sorghum genotypes differ widely in terms of sugar-related morphological parameters but are comparable with respect to their cell wall chemistry. Significance and Novelty: The use of sorghum as a bioeconomy crop has mainly focused on the extraction of sugar for bioethanol production. However, besides cell wall polymers, the potential usage of hydroxycinnamates as platform molecules for the chemical industry may improve the valorization of the residues after sugar extraction. This application appears to be fairly independent of genotype, further increasing the potential of sorghum for the bioeconomy.