Genomics of adaptation to agriculture in Striga hermonthica, a plant parasite of cereals

Bellis Emily S, Philomath OR

Investigators

Abstract

This action funds an NSF National Plant Genome Initiative Postdoctoral Research Fellowship in Biology for FY 2017. The fellowship supports a research and training plan in a host laboratory for the Fellow who also presents a plan to broaden participation in biology. The host institution for the fellowship is Pennsylvania State University and the sponsoring scientist is Dr. Jesse Lasky. Agronomic weeds pose a serious threat to agricultural productivity, and weed infestations may intensify under changing climates. To better understand interactions between biotic and abiotic stressors, this project investigates mechanisms of specialization to different host crops and abiotic environments in purple witchweed (Striga hermonthica). Parasitic witchweeds constitute the greatest biotic constraint to food production in sub-Saharan Africa and devastate yields of economically important cereals such as maize, sorghum, millet, and rice. Broader impacts include generation of new genomic and phenotypic resources to enhance development of resistant crop varieties, training of undergraduate students, and workshops in witchweed bioinformatics targeted to African scientists. Training objectives include statistical evolutionary genomics, ancient DNA sequencing, quantitative genetics, and experimental plant-parasite interactions. The main goal of this project is to better understand evolution of crop-parasite interactions across diverse abiotic environments. First, genomic signatures of host-specialization and local adaptation will be identified, using targeted exome sequencing of 200 herbarium specimens collected within the past 150 years from different hosts of origin across East and West Africa. Loci will be identified that exhibit statistical associations with environment and host of origin, with allelic variation that tracks change in regional host crop production over time. For the second aim, effects of abiotic stress on host range will be experimentally evaluated. Seed germination, early host-seeking behavior, and host resistance will be quantified under nitrogen- and water-limitation for 20 parasite populations across 60 genotypes of three agriculturally important host crops: sorghum, millet, and maize. Genomic and phenotypic resources generated during the project will be publicly accessible through online databases (NCBI; Project Unity, http://phenome-networks.com) and a dedicated project website including instructional materials, code, and molecular protocols.