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Abstract

To discover new loci controlling flowering time in natural populations, we have analyzed the flowering time of a recombinant inbred line (RIL) population derived from crosses of Niederzenz (Nd-1) to Columbia (Col-3 and Col-5; Holub, et al., Adv. Bot. Res. 24[1997]). In short days, the 98 RILs show a wide range of flowering times and preliminary QTL analysis using available genotype information indicated the existence of at least two QTL. To gain further mapping power and resolution, we genotyped the RILs for amplified fragment length polymorphisms (AFLPs) using dye-labeled primers. We identified 128 markers, which were then arranged into a genetic map using the 26 previously genotyped markers as anchors. With the new map, we detected four significant QTL: a major QTL, termed FLOWERING1, on the bottom of chromosome 1; two QTL on chromosome 2; and one QTL on chromosome 5. FLOWERING1 maps very close to FLM/MAF1, a gene encoding a MADS-domain transcription factor that has recently been shown by the Amasino and Riechmann labs to have flowering time effects in both long and short days. Additionally, the phenotypes of flm-1 and flm-2, two T-DNA alleles isolated in the Ws background, agree well with that of FLOWERING1. Upon attempting to sequence the FLM gene from Nd-1, we discovered a 6.8 kb deletion removing the entire coding region. Out of 140 accessions analyzed, only one additional accession from Niederzenz shared this deletion. Progress on molecular complementation and a quantitative complementation test will be presented.