Extent of genotypic variation for maize cell wall bioconversion traits across environments and among hybrid combinations

The utilization of maize stover as a substrate for bioenergy production demands the development of dual-purpose hybrid varieties combining both, optimal grain yield and improved biomass processing amenability. In this study, our objectives were to assess how contrasting environments influence the expression of cell wall composition and bioconversion traits relevant to cellulosic fuel production, and to study how these traits are inherited in hybrid combinations. To this end, a panel of maize double haploid (DH) lines and their corresponding test-cross (TC) offspring were tested under different locations (primarily in the Netherlands) and characterized for a variety of cell wall compositional and bioconversion features relevant to cellulosic fuel production. Overall, the DH and TC sets displayed extensive genotypic diversity in cell wall composition, polymeric ultrastructure and bioconversion characteristics. Heritability for the different traits was generally high (h 2 > ~0.60); essentially implying that systematic differences between genotypes remained constant across divergent environmental conditions. Moreover, correlations between the performance of DH lines and related TC hybrids were significant and favorable for most investigated traits. Strong associations (r > ~0.50) were especially prominent for cell wall lignin content, degree of substitution of cell wall glucuronoarabinoxylans and cell wall convertibility following pretreatment and enzymatic hydrolysis. In conclusion, complex cell wall bioconversion traits constitute accessible and reliable selection criteria for incorporation in modern breeding programs seeking to advance bio-based maize hybrid varieties. The high heritability and environmental stability of these traits guarantee high selection efficacy during the development of superior DH/inbred material; and their predominantly additive nature prescribe that preliminary selection at the inbred level will guarantee similar correlated genetic gains in hybrid breeding.