Effects of sucrose supply on growth and paraquat tolerance of the late-flowering gi-3 mutant

Mutations at the GI locus in Arabidopsis are pleiotropic: gi mutants are la te-flowering, tolerant to the toxicity of the herbicide paraquat, and have an increased starch content. We tested the effects of exogenous sucrose sup ply on the level of paraquat tolerance and on growth and development of the gi-3 mutant. Paraquat tolerance was the highest in gi-3 seedlings grown on medium containing 1% sucrose. As expected, all measured growth parameters (root length, fresh weight, anthocyanin, and sucrose content) were influenc ed by the sucrose dose, but in a number of assays (effect on fresh weight a nd developmental characteristics) the sucrose-dependent response in gi-3 wa s heterochronic. Additionally, the late-flowering phenotype of the gi-3 mut ant was reverted to wild type after prolonged growth in darkness on sucrose -containing media.