Evaluating the Cost of Domestication in Sunflower

Dittmar Emily L, Athens GA

Investigators

Abstract

This action funds an NSF National Plant Genome Initiative Postdoctoral Research Fellowship in Biology for FY 2018. 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 title of the research and training plan for this fellowship to Dr. Emily Dittmar is "Evaluating the Cost of Domestication in Sunflower". The host institutions for the fellowship are the University of Georgia and the University of Minnesota, and the sponsoring scientists are Drs. John Burke and Peter Morrell. Deleterious mutations are present in the genomes of all organisms. Recent evidence suggests that crop genomes harbor a greater number of deleterious mutations (i.e. mutational load) than their wild relatives. This mutational load may be caused by the process of domestication itself, which is often characterized by a reduction in genetic diversity and strong selection for traits of agronomic interest. This project aims to understand the causes and consequences of mutational load in cultivated sunflower. Results from this study will provide knowledge about how domestication-related processes increase deleterious variants and the effects of overall mutational load on crop performance. Training objectives include genomics and computational training in the analysis of genomic data. Broader impacts include developing lesson plans about crop evolution and genetic variation for K-12 students. The relative importance of selective sweeps versus genetic drift on the accumulation of deleterious variants in sunflower will be inferred through a determination of the genome-wide distribution of deleterious mutations and by comparing mutational load in elite cultivars to that of historical landrace varieties. These deleterious variants will be identified using computational approaches that estimate deleterious effects based on the degree of phylogenetic sequence conservation. This study will test the explanatory power of these methods using performance data from hundreds of cultivated sunflower lines to determine how well the identified deleterious variants explain variation in performance. A completely novel component to this project is that it will investigate whether the effects of deleterious variants are elevated in stressful environments. Evidence from wild species show that deleterious mutations sometimes have greater effects under stress, but the degree to which the environment interacts with mutational load in crops has so far been unexplored. Results from this research which will focus almost exclusively on publicly available data will be shared through publications, presentations at conferences, and software, code and analyses will be accessible through GitHub. Keywords: domestication, phylogenetic analysis, population genomics, sunflower, mutational load, deleterious mutations, plant biotic stress This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.