Designing Crop Varieties for Lignocellulosic Ethanol Production.

Production of ethanol and next generation biofuels from renewable lignocellulosic biomass grown in sustainable agronomic systems is currently a national priority.  Optimization of crops and crop varieties is a critical part of this process, although key steps in the production system such as pretreatment method, process of enzymatic digestion, and fermentation organism(s) remain undefined due to the infancy of the industry. Fundamental species-specific traits such as perenniality, growth habit, and physiological processes impact energy balance, yield potential, and cropping system flexibility. Benefits of new crops in the short-term are countered by historical momentum including grower experience and available equipment. From a breeding perspective, important information on the relative values of key traits related to yield, quality, carbon sequestration potential, and ecosystem services remain undefined complicating development of a selection criterion that captures and weights component traits.  The recent acceleration of genomic information and methods including whole genome transcriptional and metabolite profiles, re-sequencing of diverse genotypes within species, transgenics, and cost-effective marker platforms allows leveraging of information across species and utilization of genome-wide selection methods that have additional benefits to less-characterized and long-generation species. Alteration of specific genes will likely provide new and important variation for lignocellulosic biofuel production, but deployment of new variation will face a gauntlet of challenges including genetic background effects, and important genotype x environment interactions. In summary, the potential to rapidly and efficiently produce new varieties and to improve recently domesticated species has never been greater, but the absence of a mature industry complicates assignment of value to potential products.