A model system to study the effects of elevated CO<inf>2</inf>on the developmental physiology of roots: The use of Arabidopsis thaliana

Three developmental changes were observed in the roots of Arabidopsis thaliana (Columbia) when shoots were exposed to elevated CO2(i) The allometric coefficient, k, was enhanced significantly (P<0.001), (ii) primary root length and root extension rate were enhanced (P<0.001). Accelerated cortical cell expansion contributed to this effect and was associated with increased cell wall extensibility, measured as % plasticity. (III) Lateral root formation and extension were also increased in elevated CO2(P<0.05). These results illustrate that root growth and structure was altered following exposure to elevated CO2. The changes observed suggest that Arabidopsis provides a useful model which should, in future, be amendable to study using appropriate mutants allowing the genetic basis of the responses to be identified.