INVESTIGATORS: C. Robin Buell (PI), Michael Casler, Gautam Sarath
INSTITUTIONS: Michigan State University, USDA ARS U.S. Dairy Forage Research Center, USDA ARS Grain Forage and Bioenergy Research Unit
PROJECT SUMMARY: A number of biofuel feedstock research programs are focused on improving lignocellulosic biomass production in grass species such as maize, sorghum, Miscanthus, and switchgrass. This is due to the potential for energy conversion of lignocellulosic biomass, established agricultural production methods for these grass species, and high biomass yield potentials. Switchgrass is a native North American perennial grass that has exceptional promise as a biofuel feedstock due to its high biomass potential on marginal lands with limited amendments. One key method to increase biomass production of switchgrass is to extend the latitudes in which lowland ecotypes are grown. However, the lowland ecotypes are not cold tolerant. Our proposed research will identify metabolites, alleles, transcripts, and regulatory RNAs associated with cold hardiness in switchgrass that will 1) substantially advance our understanding of the biochemical, physiological, and molecular mechanisms for cold adaptation in switchgrass and 2) provide molecular tools to improve switchgrass breeding efficiency.
One of the proposed mechanisms to increase switchgrass biomass is to grow lowland cultivars in more northern latitudes where they have higher yield potential, due in part to their significantly later flowering time at these latitudes. However, lowland types are not adapted to the colder winter conditions in northern climes and exhibit low survival rates when grown at latitudes outside their adapted range. Many unadapted populations possess a small frequency of individuals that can survive the winter, indicating that, within the collective genetic diversity of the population, alleles are present that confer cold tolerance. If these alleles could be catalogued and converted into molecular markers, they would facilitate accelerated breeding and provide a mechanism to improve the efficiency of breeding switchgrass cultivars with high biomass and cold hardiness. Our hypothesis is that alleles favorable to cold hardiness will be enriched in individuals that survive over-wintering conditions outside their native hardiness zone and that these alleles will be under-represented in individuals within the population that fail to survive over-wintering. Using allele frequencies determined through bulk segregant exome capture sequencing, we will identify genes, and specifically alleles, important to cold hardiness in lowland switchgrass populations. Using bulk segregant transcriptome sequencing, we will identify transcripts and regulatory RNAs associated with successful senescence and cold hardiness that will permit prediction and validation of key metabolites involved in cold adaptation. Data from this project will be central to furthering our understanding of cold tolerance in switchgrass and in identify alleles that that can be used in breeding programs to increase switchgrass biomass.
This project integrates natural variation with genomics, bioinformatics, physiology, molecular biology, and biochemistry to identify genes, and more importantly, alleles relevant to cold hardiness that can be incorporated rapidly into switchgrass breeding programs to increase biomass and survival in northern latitudes.
Name: Buell, Robin