QTL ANALYSIS OF FLOWERING TIME IN ARABIDOPSIS-THALIANA

Quantitative trait loci (QTL) analyses based on restriction fragment l ength polymorphism maps have been used to resolve the genetic control of flowering time in a cross between two Arabidopsis thaliana ecotypes H51 and Landsberg erecta, differing widely in flowering time, Five qu antitative trait loci affecting flowering time were identified in this cross (RLN1-5), four of which are located in regions containing mutat ions or loci previously identified as conferring a late-flowering phen otype, One of these loci is coincident with the FRI locus identified a s the major determinant for late flowering and vernalization responsiv eness in the Arabidopsis ecotype Stockholm. RLN5, which maps to the lo wer half of chromosome five (between markers mi69 and m233), only affe cted flowering time significantly under short day conditions following a vernalization period. The late-flowering phenotype of H51 compared to Landsberg erecta was due to alleles conferring late flowering at on ly two of the five loci. At the three other loci, H51 possessed allele s conferring early flowering in comparison to those of Landsberg erect a. Combinations of alleles conferring early and late flowering from bo th parents accounted for the transgressive segregation of flowering ti me observed within the F-2 population. Three QTL, RLN1, RLN2 and RLN3 displayed significant genotype-by-environment interactions for floweri ng time. A significant interaction between alleles at RLN3 and RLN4 wa s detected.