January 23, 2004

Kristen Wardlaw, California State University, Los Angeles

Long Distance Signaling Between Arabidopsis thaliana Leaves and Roots in Response to Changes in Growth Temperature

Kristen Wardlaw, California State University, Los Angeles
Owen Atkin, University of York, United Kingdom
Scott Nickoliasen, California State University, Los Angeles

Plants release more hydrocarbons into the troposphere than all industrial activities combined. At the same time, the oxygen produced by plants is essential to life on earth. A better understanding of what effects environmental stresses have on plant processes will better enable us to predict the impact of future climate change. Plants can adjust to their environment by altering rates of photosynthesis and metabolism as temperature changes throughout the year (thermal acclimation). Many of the mechanisms underpinning thermal acclimation have been elucidated for leaves that directly experience a change in growth temperature. It is not known, however, whether tissues need to directly experience cold in order to exhibit cold-acclimated characteristics. My research focused on the effects of indirect and direct exposure to low and moderate temperatures using Arabidopsis thaliana. Temperature controlled growth cabinets were used in conjunction with water baths to affect the different treatments. Rates of photosynthesis (CO2 uptake) and dark respiration (CO2 release by leaves and O2 uptake by roots) were measured using a LI-COR 6400 portable photosynthesis system; chlorophyll fluorescence was measured with a pulse modulation chlorophyll fluorometer. Response varied between the four treatments (warm roots/ warm shoots; warm roots/ cold shoots; cold roots/ warm shoots; cold roots/ cold shoots) in rates and capacities of photosynthesis. Plants were able to affect acclimations in areas not experiencing adverse temperatures. Leaf expansion was also slightly affected. Warm developed leaves shifted into the cold showed a dramatic drop in photosynthetic capacity followed by a slight recovery over time.