Evidence is accumulating that the effect of CO2 on time of flowering involves interactions with photoperiod, but the basis for this interaction is unclear. We examined which components of the photoperiod flowering pathway account for this interaction in Arabidopsis thaliana. Ten mutants deficient in particular loci in the photoperiod pathway, as well as the wild type, were grown under short and long days at either ambient or elevated CO2. We determined leaf number at bud formation and the number of days required or induction of flowering.
Results/Conclusions
Elevated CO2 had an effect on the blue light receptor, CRYPTOCHROME 2 under short days, and on the GIGANTEA gene under long days that increased the number of leaves required for bud formation, and an effect on FLOWERING LOCUS T in both long and short days that reduced the number of leaves required. Elevated CO2 also affected flowering by increasing the rate of leaf production. The net effect of elevated CO2 on time of flowering varies because CO2 has a complex array of effects on different elements of the developmental pathway leading to flower induction that may either hasten or delay flowering depending upon the influence of other environmental factors such as photoperiod.
