BREEDING RESILIENT, DISEASE-RESISTANT SWITCHGRASS CULTIVARS FOR MARGINAL LANDS

'Breeding resilient, disease-resistant switchgrass cultivars for marginal lands'J. Carlson, Ph.D., Penn State University (Principal Investigator)T. Bell, Ph.D., Penn State University (Co-Investigator)M. Hall, Ph.D., Penn State University (Co-Investigator)J. Lasky, Ph.D., Penn State University (Co-Investigator)S. Bonos, Ph.D., Rutgers University (Co-Investigator)J. Hansen, Ph.D., Cornell University (Co-Investigator)D. Viands, Ph.D., Cornell University (Co-Investigator)The goal of this project is to leverage previous research results to accelerate the development of superior, disease-resistant, climate-resilient switchgrass (Panicum virgatum L.) cultivars for expanding the range of biomass cultivation in the Northeast. Selections from previous progeny trials will be augmented with new selections from evaluations conducted in a range-wide association mapping family. Candidate genes for disease resistance and genotype-by-environment interactions relevant to the holistic switchgrass system at marginal growing sites will be identified for productivity improvements.Switchgrass is a fast growing, perennial, warm-season grass, native to much of North America and has great potential for development as a bioenergy crop. In the humid Northeast, fungal diseases are prevalent and may reduce yield and quality of crops. This project will focus on anthracnose (caused by Colletotrichum navitas) and Bipolaris leaf spot (caused by Bipolaris oryzae), for which the PIs have conducted heritability studies and have identified segregating variation in mapping populations for these diseases. This research will be critical for future sustainable utilization of switchgrass in warm/humid environments in the Northeastern U.S. that are prone to heavy disease pressure. The resources developed through this project will increase the efficiency of selection for switchgrass disease resistance and ultimately improve plant health, biomass yield, and long term bioenergy sustainability of switchgrass on marginal lands.Our objectives are to: 1) Expand the breeding of superior, disease-resistant cultivars for high productivity in marginal environments in the Northeast; 2) Discover genes for resistance to anthracnose and Bipolaris diseases and for bipmass yield in switchgrass; and 3) Identify associations between soil microbial communities, plant genotypes, environment factors that effect yield characters and disease susceptibility in in switchgrass.This project will leverage results and materials from several key research programs, including two recent USDA CAP Bioenergy Projects. This includes selections, cultivars, populations, progeny trials, yield and disease severity data for switchgrass from the NEWBio project (the Northeast Woody/warm-season Biomass consortium funded by USDA-AFRI Grant #2012-68005-19703). In addition, we have replicated a previously established switchgrass association panel (USDA-AFRI Grant #2011-68005-30411) composed of 528 genotypes from across the species' range at three sites with contrasting growing conditions near Cornell, Rutgers and Penn State universities, including a reclaimed surface mine. This panel was previously genotyped by sequencing, providing over a million single nucleotide polymorphisms for identifying associations of genes with phenotypic variation in response to anthracnose and Bipolaris leafspot diseases, as well as growth traits, and genotype-by-environment interactions, including soil microbiome composition. Candidate genes for disease resistance will also be identified by conducting differential gene expression analyses and mapping Quantitative Trait Loci in a population that segregates for anthracnose-susceptibility and -resistance. Metagenome sequencing of soil samples from the root zone of plants in the association panel will be used to reveal specific interactions of microbes with switchgrass plants based on host plant genotype and planting site conditions.The impacts of this project include: A better understanding of disease resistance mechanisms in switchgrass, and the role of both genotype and environmental factors on disease and plant productivity. New tools for selection for disease resistance in switchgrass breeding programs will be provided as QTL markers and candidate genes. And new populations, cultivars and germplasm will be provided to accelerate development and deployment of disease resistant and high-yielding switchgrass cultivars for expanding perennial biomass cultivation on marginal sites such as abandoned farm and mind lands.