Methods:
Objective 1: How does metabolomic diversity in plants influence soil microbial community composition? To address this objective, I will collect rhizosphere soil from 30 genets and 3 plants per genet from the UMBS population, extract DNA and conduct bacterial (16S) and fungal (ITS) metabarcoding to identify microbial community composition. I will use a MANOVA to determine whether plant metabolome and/or soil characteristics predict microbial community composition and conduct a Genome-Wide Association study (GWAS) to determine if there are plant gene regions associated with the microbial community composition. As a first step to validating the use of hyperspectral imaging to metabolomically identify plants I will image genets and correlate spectra with their known metabolome. I will repeat the MANOVA and other analyses using the hyperspectral data.
Objective 2: Does variation in Mean Annual Precipitation (MAP) alter plant metabolomes and soil microbial community composition? I will examine the influence of the climatic gradient on common milkweed chemical and other phenotypic traits as well as soil microbiome community composition. I will use resources such as iNaturalist to identify 3 sites containing multiple common milkweed genets at 3 levels of precipitation along the precipitation gradient. I will measure metabolomic traits (cardenolides and latex production) using standard chemical approaches (e.g., gas chromatography) and hyperspectral imaging, and will measure the following phenotypic and phenological traits: plant height, leaf size, leaf shape, seed pod number, seed pod size, seed size, flower number, and flowering time12. I will collect soil microbial community samples as in Objective 1. I will use MANOVA and other multivariate tools to determine if there is a relationship between MAP, plant secondary metabolomes, and plant traits.
Objective 3: Does climate history predict responses to variation in climate? To test Objective 3, I will manipulate milkweed genets from across the MAP gradient, water availability, and soil community composition in a greenhouse. I will use hyperspectral and thermal imaging to assess metabolomes in milkweed genets and in response to water availability.