Plant & Animal Genomes XIII Conference

January 15-19, 2005
Town & Country Convention Center
San Diego, CA

Comparison Of Three Brassica oleracea BAC Clone Sequences With Their A. thaliana Counterparts Reveals Differences In Gene Density

Muqiang Gao¹ , Genyi Li² , Bo Yang¹ , Carlos F. Quiros¹

¹  Department of Plant Sciences, University of California, Davis, CA 95616

²  Department of Plant Science, University of Manitoba, Winnipeg Manitoba, Canada R3T 2N2

We sequenced three Brassica oleracea (DH broccoli Early Green) BAC clones, B13H21, B19N3, and B21F5 of 101 kb, 97 and 82 kb in length, respectively. B21H13 harbors 23 genes while the corresponding region in A. thaliana on chromosome IV contains 37 genes. All 23 common genes have the same order and orientation in both Brassica and Arabidopsis. This clone harbors gene BoGSL-ALK (2-oxoglutarate-dependent dioxygenase, AOP2 gene in A. thaliana) controlling side chain desaturation. BAC clone B21F5 contains 11 genes while the corresponding region in A thaliana on chromosome V contains 14 genes. All 11 common genes have the same order and orientation in both species. It harbors gene BoGSL-ELONG (methylthioalkylmalate synthase; MAM in A. thaliana) coding for 4C-side chain glucosinolates synthesis. BAC clone B19N3 contains 10 genes including two TEs. The corresponding region in A. thaliana on chromosome I contains 15 genes. This clone harbors candidate gene BoGSL-PRO, probably coding for 3C-side chain glucosinolate biosynthesis. There is colinerity for 5 of the 10 genes at one end of the clone, sharing the same order and orientation in both Brassica and Arabidopsis. All the exons constituting the 44 genes found in the three BAC clones have high conservation between the two species (80 to 90% at the nucleotide level), whereas the introns vary in length and sequence. The lower gene density observed in the three B. oleracea BAC clones compared to A. thaliana is due to longer introns, and spacers, and presence of TEs.