Daniel Hemphill


Education: Bachelor of Science in horticulture (December 2021)

Currently pursuing an Master of Science in agriculture (horticulture and crop sciences) at Ohio State University

McNair Project: Freezing Tolerance of Arabidopsis Accsessions Relating to Latitude and Lipid Composition (2020)

Mentor: Ruth Welti, Ph.D.

McNair Project: Arabidopsis’ Freeze Tolerance and Clinal Variation (2021)

Mentor: Ruth Welti, Ph.D.

Accessions of Arabidopsis thaliana collected in different geographic locations vary in tolerance to freezing, but the freezing tolerance of less than 100 accessions has been directly determined. In this work, the tolerance of 320 accessions to freezing stress is being determined. During freezing, the levels of many different plant components increase or decrease, and it is hypothesized that changes in lipids play an important role in freezing tolerance or susceptibility. Lipids are involved in maintenance of membrane structure, which is critical to cell integrity. Lipids are also putatively involved in signaling. The freezing tolerance data will be correlated with the levels of various lipids within the plants across accessions to identify the lipids that may play roles in freezing tolerance. The experiment involves planting, stratification, a 31-day growth period, a 3-day cold acclimation at 4°C, a gradual and controlled freezing regimen dropping to -13˚C in a freezing chamber, post-freezing maintenance for 2 weeks, and determination of the tolerance score, which is the percentage of each plant’s rosette that remains alive after the freezing regimen. For each accession, 3 plants on each of 8 different trays are scored. Data for the tolerance of the 24 plants of each accession will be averaged. The tolerance score of each accession under freezing will be correlated with the level of each lipid and with latitude and available climatic data. Correlation coefficients describe the direction and degree of correlation. The availability of these data on the freezing tolerance of additional accessions of Arabidopsis thaliana will be valuable, not only in this research on the role of lipids in freezing tolerance, but to researchers investigating other possible mechanisms leading to freezing tolerance. Understanding the mechanism of freezing tolerance will better situate humanity to improve plant freezing tolerance in crops with agricultural, industrial, or even space exploration applications.