Project Number: 5440-21000-030-02
Project Type: General Cooperative Agreement

Start Date: Dec 01, 2009
End Date: Aug 31, 2013

Objective:
The objectives of this proposal are (1) To utilize novel genomic and biochemical tools to investigate molecular mechanisms underpinning nutrient partitioning and remobilization in crowns and rhizomes of switchgrass cultivars with divergent winter-hardiness. (2) To use high-throughput DNA sequencing to query transcript abundance (levels of gene expression) in specific populations of switchgrass plants during regreening and dormancy. (3) To study the genetic variation (extent of linkage disequilibrium in populations) and eventually develop genetic markers for cold-adaptation and fitness traits in switchgrass plants being developed for Central and Northern USA that show significant hybrid vigor (heterosis).

Approach:
Five different strains of switchgrass plants that differ in their cold-hardiness and fitness parameters will be planted in the fields. Crowns and rhizomes will be harvested from these plants at specific times over two growing seasons for genetic (High-throughput pyrosequencing; 454 transcriptomics) and metabolite analyses. Additional plants will be subjected to isotope-tracer experiments using stable isotopes for carbon (C-13) and nitrogen (N-15) to query nutrient recycling over two growing seasons as affected by the genetic background of the plants. These data will permit improved insights in the molecular and physiological events that impact perenniality and fitness in switchgrass. Obj. 2. Using genomic approaches (454 pyrosequencing and bioinformatics), we will discover additional genes impacting fitness using individual plants from switchgrass populations divergently selected over ~30 years for ruminant digestibility. These plants are a unique genetic resource unavailable elsewhere, and show improved conversion to ethanol and decreased winter survival. Obj. 3. We will attempt to uncover marker-trait associations that can be used to reduce the generations, and within generation time and expense of phenotyping in the breeding process by use of marker assisted selection (based on genes uncovered in Obj.1 and Obj. 2). Over 2000 plants from various genetic backgrounds have been planted in the field for these analyses.