Developing a Molecular-Assisted Hybridization Strategy for the Improvement of the Quality of Poplar Biomass for The United States` Bio-Fuels

Highly productive, third-rotation commercial plantations have been successfully managed in the United States by the pulp and paper, timber, and the environmental-remediation industries for more than 40 years with great success in terms of wood yields and job creation. The success of the poplar plantation industry has consistently been shown to be dependent the propagation of elite varieties that have undergone hybridization and intense selection for improved agronomic characteristics. Hybrid poplar will similarly play a large role in the future supply of cellulosic energy feedstock as a key component of the Nation's 30x30 goals for the renewable transportation fuels industry. However a new class of poplar varieties of improved chemistry composition will be needed that are capable of bio-fuels manufacture with improved conversion economics. The breeding of such varieties will require the development and integration of novel molecular tools into existing traditional hybridization and varietal selection program. To accomplish this, GreenWood Resources currently conducting an association genetics study to identify genes controlling cellulose production in black cottonwood (Populus trichocarpa) based on single nucleotide polymorphisms (SNP's). We are now completing a comparative study with European black poplar (P. nigra) so as to augment GreenWood's conventional hybridization program for these two important poplar species using molecular markers and bioinformatics to improve biomass composition and the economics of liquid fuels conversion. (The goal is a re-designed reciprocal recurrent selection program for inter-sectional hybridization of P. trichocarpa and P. nigra. ) A large 612-genotype collection of P. nigra has been cloned and established at two contrasting locations in the Pacific Northwest. We have sequenced the same lignin and cellulose biosynthetic pathway genes identified in the P. trichocarpa study to discover new SNPs. We propose to: 1) Phenotype the 612 clones for an array of chemical and structural traits at each of the two locations, 2) Genotype the collection for important SNPs, and 3) Study the genotype-phenotype associations and the effect to which they interact with planting site. The comparative study in P. nigra will also provide insight into the pattern of genetic diversity between the two species from distinct sections of the genus. The comparison will also advance our understanding of the manner in which reciprocal parental populations should be managed as a marker-assisted breeding program for improved first-generation hybridization for enhanced bio-fuels application.