COMPARATIVE QTL MAPPING OF PLANT MORPHOLOGY IN Brassica oleracea.

¹ Dept Soil and Crop Science, Texas A&M University, College Station, TX 77843

² Novartis Agricultural Discovery Institute (NADI) (current address)

³ Applied Genetic Technology Center, University of Georgia, Athens, GA 30602

The genus Brassica (tribe Brassiceae), including many important crops with diverse morphology, is in the same taxonomic family (Cruciferae) as Arabidopsis thaliana, the first flowering plant whose genome will be completely sequenced. The genomes of Brassica and Arabidopsis share similar gene order along large chromosomal segments, providing a solid foundation for comparative biology. Their close relationship suggests that crop plants of the genus Brassica will be among the earliest beneficiaries of the Arabidopsis sequence. We have identified 86 quantitative trait loci (QTL) that control 8 curd-related traits, 47 QTLs that affect plant size and shape, and 40 QTLs influencing seed-related traits, in three Brassica oleracea F2 populations derived from crosses of rapid-cycling Brassica to three B. oleracea varieties, Cantanese, Pusa Katki and Bugh Kana. There was relatively little correspondence of QTLs among different Brassica genotypes, supporting other data that suggest this genus is rapidly-evolving. In many cases, genome alignment suggested possible candidate genes from Arabidopsis that might be further investigated to determine if they account for phenotypic variation in Brassica. The Arabidopsis/Brassica system is an important example of both the challenges and opportunities associated with extrapolation of genomic information from facile models to large-genome taxa including major crops.