Impact of Heat Stress on Reproductive Success in Arabidopsis thaliana and Boechera depauperata

Committee Members

• Dr. Elizabeth Waters (Biology)
• Dr. Chun-Ta Lai (Biology)
• Dr. Janet Franklin (Geography)

Abstract

Impact of Heat Stress on Reproductive Success in Arabidopsis thaliana and Boechera depauperata

Plants are sessile organisms that must withstand their changing environment to survive, including harsh conditions such as drought, salinity, and high temperatures. Due to climate change, heatwaves have become more severe in terms of both duration and intensity. Thus, the effects of rising temperatures on the ability of native plants to reproduce have become a growing concern. Much is known about how model plants respond to a single heat stress, but the effects of repeated heat stress on plants have not been widely studied.

The goal of this study is to examine the impact of single and repeated heat stress on the photosynthetic activity and fecundity of two species in the Brassicaceae family, the model species Arabidopsis thaliana and a native California mustard (Soldier Rockcress) Boechera depauperata. Plants were exposed to a single stress (four-day heatwave) during the seedling stage, or a single heat stress (four-day heat wave) at the onset of flowering, or a repeated heat stress where plants were stressed at both the seedling stage and at the onset of flowering.

The impacts of these heat stresses on plant physiology were investigated by using Pulse Amplitude Modulated (PAM) Fluorometry. PAM fluorometry was used to estimate the impact of heat stress on the quantum yield (YII) of Photosystem II. YII was examined both immediately after the four-day heat stress and after a five-day recovery period. These measurements were used to determine that the photosynthetic machinery was damaged by heat stress. After the stress treatments, plants were returned to control conditions and allowed to flower and set seed.

Plant fecundity was measured by the number of siliques produced, the length of the siliques, the average weight of seeds, and the germination rate of seeds. Neither plant exhibited a decrease in the quantum yield of photosynthesis after heat stress, but heat stress did have an impact on fecundity.