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

Euphytica (2015) 206:501–511 DOI 10.1007/s10681-015-1517-x Extent of genotypic variation for maize cell wall bioconversion traits across environments and among hybrid combinations Andres F. Torres . Cornelie M. M. Noordam-Boot . Oene Dolstra . Louis Vlaswinkel . Richard G. F. Visser . Luisa M. Trindade Received: 14 January 2015 / Accepted: 8 July 2015 / Published online: 16 July 2015 Ó The Author(s) 2015. This article is published with open access at Springerlink.com Abstract 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 A. F. Torres
O. Dolstra
R. G. F. Visser
L. M. Trindade (&) Wageningen UR Plant Breeding, Wageningen University and Research Center, P.O. Box 386, 6700, AJ, Wageningen, The Netherlands e-mail: A. F. Torres Graduate School Experimental Plant Sciences, Wageningen University, Wageningen, The Netherlands C. M. M. Noordam-Boot
L. Vlaswinkel Limagrain Nederland B.V., Rilland, The Netherlands (h2 [ *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. Keywords Maize
Cell wall composition
Biofuel
Heritability
Environment
Hybrid Introduction As the most important crop worldwide in relation to global acreage, maize is envisioned to play an essential role in the wide-scale realization and commercialization of cellulosic fuel technologies (van der 123 502 Weijde et al. 2013). In fact, with an unrivalled production and distribution infrastructure, and nearly 1300 million tons of dry stover available annually, maize is warranted to become the first large-scale lignocellulosic crop in the industry (Torres et al. 2014). Conceivably, the intensive utilization of maize stover as a substrate for bioenergy production will create a demand for dual-purpose hybrid varieties combining both, optimal grain yield and improved stover quality (Torres et al. 2014; van der Weijde et al. 2013). In this context, a pivotal objective for breeding ‘‘bioenergy’’ maize is improving complex cell wall characteristics influencing the industrial quality of its biomass (Torres et al. 2014). Numerous studies have demonstrated that bioenergy crops diverging in cell wall constitution exert a differential influence on the technical efficacy of biomass-to-fuel conversion platforms (Dien et al. 2009; Fu et al. 2011; Torres et al. 2013, 2015). These investigations have invariably led to the recognition that the economic and environmental performance of the cellulosic fuel industry can be improved through the selection of biomass substrates which require lower energetic and chemical inputs for their deconstruction (Torres et al. 2013; van der Weijde et al. 2013). With a wealth of dedicated agronomic and genomic resources, advancing dual-purpose maize with improved biomass-processing amenability is a realistic prospect (Torres et al. 2014). Extensive evidence has demonstrated that maize conceals a considerable degree of genetic variation for cell wall compositional traits of beneficial value for bio-based industrial applications (Lorenz et al. 2009, 2010; Torres et al. 2015). These results suggest that favorable genetic gains for complex cell wall characteristics are attainable by exploiting available germplasm resources through classical breeding and selection. Despite these promising projections, nevertheless, much remains to be investigated in relation to how contrasting environments influence the expression of cell wall composition and bioconversion traits relevant to cellulosic fuel production, and how the latter are inherited in hybrid combinations. Certainly, this information will be deemed essential when designing selection strategies that maximize the efficacy of bio-based maize breeding endeavors. This study was concerned with two distinct, yet inter-related objectives. The first one was to assess whether heritable variation (at the inbred level) for 123 Euphytica (2015) 206:501–511 maize cell wall composition and degradability characteristics relevant to cellulosic fuel production remains stable across contrasting environments. The second one was to investigate how this variation, especially in relation to bioconversion traits, is inherited and expressed in hybrid combinations. Collectively, these analyses would yield insights into the technical feasibility of exploiting standing variation for complex maize cell wall characteristics at the inbred level for the production of superior hybrid cultivars with reduced lignocellulose recalcitrance and improved processing amenability. To this end, a panel of maize double haploid (DH) lines and their corresponding test-cross 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 via dilute-acid hydrolysis and enzymatic saccharification. Materials and methods Plant material A maize population of doubled haploids (DHs), property of Limagrain Nederland B.V. (Rilland, The Netherlands), was grown in 2009 at Wouw, The Netherlands, and was characterized for variation in cell wall composition and degradabilit (...truncated)