2019 ASHS Annual Conference

Global temperatures are increasing due to climate change, causing variations in precipitation and an accelerated risk of drought. This has major impacts on agricultural production and food security worldwide. One possible solution to mitigating the effects of climate change is genetic crop improvement, specifically through improved tolerance to abiotic stresses. Crop centers of domestication and diversity are an important source of genetic variation, which can be utilized in plant breeding. Wild, semi-domesticated, and landrace varieties may have local adaptations to specific environments that allow them to outperform non-local genotypes under the same conditions. Mexico is the center of domestication for chile pepper (Capsicum annuum L.). Chile pepper is found in a broad climatic range, in varying elevation, soils, and precipitation. Previously, an environmental association analysis was conducted on Mexican landraces and wild accessions in order to identify regions of the genome that contribute to drought tolerance. Twelve priority loci were identified as associated with drought-prone environments. The objective of this study was to sequence haplotype blocks containing the priority loci and expand into U.S. germplasm. A greenhouse drought experiment was conducted on 25 genotypes including 18 U.S. cultivars and seven previously evaluated Mexican accessions. Seedlings were transplanted into 6-liter pots after seven weeks and drought was applied one week later. Two treatments were applied: a daily watering (control) and weekly watering (drought). Yield (fruit count and weight), flowering date, branching, and above-ground biomass data were collected. Gas exchange and chlorophyll fluorescence were also measured using the LI-6800. Results indicate differences in plant performance under drought stress and sequence variation in priority haplotype blocks. Results could provide valuable insight into physiological and agronomic performance of pepper under drought stress and may be useful for continued breeding efforts.