GENES CONFERRING LATE FLOWERING IN ARABIDOPSIS-THALIANA

Three naturally occurring late flowering, vernalization responsive ecotypes of Arabidopsis thaliana, Pitztal, Innsbruck and Kiruna-2, were each crossed with the early flowering ecotypes of Landsberg erecta, Columbia and Niederzenz. Analysis of the subsequent generations suggested that late flowering in Kiruna-2 is recessive and mainly determined by a single, late flowering gene. This late flowering gene is not, however, the same as that in any of the late flowering mutants generated in the Landsberg erecta background. Both Pitztal and Innsbruck appear to contain the same dominant gene which confers late flowering to these ecotypes. The early flowering parents Niederzenz and Landsberg both contain genes which modify the phenotype of this dominant late flowering locus, causing F-1 plants to flower either earlier (Landsberg) or later (Niederzenz) than the late parent. Mapping of the dominant late flowering locus from Pitztal demonstrated that late flowering co-segregated with an RFLP marker from one end of chromosome 4. This is a similar position to that of FLA, the gene responsible for late flowering of the Arabidopsis ecotypes Sf-2 and Le-O.