Effects of elevated carbon dioxide and sucrose concentrations on Arabidopsis thaliana root architecture and anatomy

Plant root growth is known to be influenced by higher levels of atmospheric carbon dioxide (CO2). Roots of some species grown in hydroponics under elevated CO2 concentrations may be more competitive sinks for photosynthetic assimilates than roots grown under lower CO2 conditions. Root branching patterns may also be influenced by elevated CO2 concentrations. Studies have also shown that factors such as soil compaction, salinity and the availability of nitrate, phosphorous, oxygen and water also influence root growth, and the effects of higher CO2 on roots can be confounded by such environmental factors. This study evaluated the effects of elevated carbon dioxide and sucrose concentrations on Arabidopsis thaliana root growth, morphology, and architecture. Both ambient and elevated CO2 levels were used along with various sucrose concentrations. The study revealed that A. thaliana plants grown on a phytagar medium in small chambers with elevated CO2 had longer roots, more lateral root growth than plants grown in ambient CO2. Roots in elevated CO2 were found to have wider root diameters, and more secondary growth. The addition of sucrose to the media closely resembled the effects of elevated CO2. In addition, the increase in sucrose concentration had a bigger effect on root morphology under ambient, than elevated CO2. Therefore, both elevated CO2 and increased sucrose concentrations promote root growth by increasing their number, length, and diameter. The dichotomy branching index (DBI) also dropped resulting in a more dichotomous branching pattern. 34 refs., 5 figs