Presenter: Vivian Bernau
Advisors: Drs. Leah McHale and Kristin Mercer
Proposal Type: MS Proposal
Title of Presentation: Exploring Climate Adaptations in Chile Pepper (Capsicum annuum) of Southern Mexico
Abstract: Chile peppers (Capsicum annuum), which grow in southern Mexico on a environmental gradient from warm and humid coastal areas to the cool, dry highlands, present a unique opportunity to study the range of environmental tolerance and adaptation. Understanding how chile peppers have adapted to local conditions will provide insight into the importance of specific environmental factors in organizing diversity across the landscape, and highlight traits with potential for future crop improvement. Over recent years, our international research team has sampled more than 200 plants from wild, semi-wild and domesticated populations across southern Mexico. Seed from these original collections will undergo one generation of increase in the greenhouse to eliminate maternal environmental effects in seeds used for planned phenotyping experiments. Genome-wide genotyping (GBS) will be conducted on these parent plants. I will conduct two experiments aimed at assessing short-term and long-term resistance to abiotic stress. I will study short-term resistance to drought and heat stress in seedlings by overlaying factorial environmental treatments (simulating the interaction between cool highland/warm lowland temperatures and moist coastal/drier inland environments of Oaxaca, Mexico) onto chile pepper accessions from our collection. I will assess long-term (i.e. full life cycle) drought resistance by comparing the effect of a field capacity treatment with an empirically determined water stress treatment across accessions in factorial combination. Habitat drought stress indices based on the Thornthwaite potential evapotranspiration (PET) model and the Hamon estimator will be assessed as drought resistance predictors. Using a genome wide association study (GWAS) approach, I will identify significant associations between genetic markers and observed values of gas exchange, as well as plant morphology, growth characteristics and overall fitness. Information gathered through this study will provide evidence for the genetic basis of both adaptive variation and phenotypic plasticity, therefore furthering the understanding of genetic diversity in chile peppers.