DNA Research Advance Access originally published online on November 2, 2009
DNA Research 2009 16(6):311-323; doi:10.1093/dnares/dsp020
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
A Brassica rapa Linkage Map of EST-based SNP Markers for Identification of Candidate Genes Controlling Flowering Time and Leaf Morphological Traits

Laboratory of Plant Breeding and Genetics, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba, Sendai, Miyagi 981-8555, Japan
Received 30 June 2009 ; accepted 20 September 2009.
For identification of genes responsible for varietal differences in flowering time and leaf morphological traits, we constructed a linkage map of Brassica rapa DNA markers including 170 EST-based markers, 12 SSR markers, and 59 BAC sequence-based markers, of which 151 are single nucleotide polymorphism (SNP) markers. By BLASTN, 223 markers were shown to have homologous regions in Arabidopsis thaliana, and these homologous loci covered nearly the whole genome of A. thaliana. Synteny analysis between B. rapa and A. thaliana revealed 33 large syntenic regions. Three quantitative trait loci (QTLs) for flowering time were detected. BrFLC1 and BrFLC2 were linked to the QTLs for bolting time, budding time, and flowering time. Three SNPs in the promoter, which may be the cause of low expression of BrFLC2 in the early-flowering parental line, were identified. For leaf lobe depth and leaf hairiness, one major QTL corresponding to a syntenic region containing GIBBERELLIN 20 OXIDASE 3 and one major QTL containing BrGL1, respectively, were detected. Analysis of nucleotide sequences and expression of these genes suggested possible involvement of these genes in leaf morphological traits.
Key words: DNA markers; synteny; bolting time; leaf lobe; leaf hairiness
* To whom correspondence should be addressed. Tel. +81 22-717-8650. Fax. +81 22-717-8654. E-mail: nishio{at}bios.tohoku.ac.jp
Present address: Tea Research Center, Shizuoka Prefectural Research Institute of Agriculture and Forestry, Kurasawa 1706-11, Kikukawa, Shizuoka 439-0002, Japan.