FACTORS INFLUENCING THE VERNALIZATION RESPONSE AND FLOWERING TIME OF LATE FLOWERING MUTANTS OF ARABIDOPSIS-THALIANA (L) HEYNH

The late flowering mutants of Arabidopsis thaliana provide an excellent system to investigate the factors controlling floral induction and the vernalization response. Previous studies with these mutants have analysed their response to the duration of vernalization, and growth in different light conditions. Mere, we examined the effect of plant age on the vernalization response and the influence of different light conditions during the vernalization treatment. Wild type Landsberg erecta (Ler) and lines carrying the fca (classified as vernalization responsive, daylength responsive) or cc (classified as daylength insensitive, vernalization insensitive) mutations were analysed. The response to vernalization at different plant ages was qualitatively the same for Ler, fca, and co, but differed in degree and timing. In Ler, fca and co vernalization was more effective in darkness than in short days (SD); or continuous light. The series of late flowering mutants were used to examine the effects of a number of compounds previously shown to influence flowering. Gibberellin A(3) and 5-bromodeoxyuridine accelerated flowering for all the mutants analysed, and were additive to a vernalization treatment for fca. The fca mutant responded to the same range of gibberellins as Ler, but to a greater degree. Choline chloride delayed flowering, but this effect was reversed by vernalization in most of the vernalization-responsive mutants. None of the mutants showed a specific loss of response to any particular compound.