FLORAL TRANSITION MUTANTS IN ARABIDOPSIS

An inventory of genetic differences in flowering time in Arabidopsis i s presented and discussed, Many genes influence the transition to flow ering in a quantitative way, Two groups of mutants and natural variant s can be distinguished: those that are responsive to environmental fac tors and those that are less responsive or unresponsive, It is possibl e that all late/early-flowering mutants isolated to date carry a mutat ion with an effect, either promotive or repressive, on a floral repres sor, The interaction between light perception and flowering has been s tudied by analysis of phytochrome- and cryptochrome-deficient mutants, which showed that phyA and probably also cryptochrome have a promotiv e role in flowering, whereas phyB and other stable phytochromes have a n inhibitory role, A circadian rhythm is important in establishing day length sensitivity, as was shown by the phenotype of the elf3 mutants.