Figure 3

BoFRIa and BoFRIb map to regions of the B. oleracea genome that are non-syntenic with A. thaliana. (a) Comparison of BoFRIa genomic clone with annotated regions of A. thaliana chromosomes 4 and 5 represented in the 5' to 3' orientation. Solid black rectangles correspond to the three exons that make up FRI. Arrows indicate the orientation of other genes. (i) BoFRIa, genomic clone. (ii) Region of A. thaliana chromosome 5 containing an iron superoxide dismutase (FSD2, At5g51100) and At51090 showing homology to FRI intron 1 and exon 3. (iii) Region of A. thaliana chromosome 4 containing AtFRI and At4g400651 showing homology to exon 9 of FSD2. ( b ) Proposed derivation of A. thaliana and B. oleracea linkage groups from ancestral karyotype (AK6 and AK8) as suggested in [53] showing the position of FRI and FLC. The rearrangement of ancestral blocks W and R results in orthologues of FRI and FLC being brought into close proximity in the ancestral Brassica genome. This region is present on chromosomes C2, C3 and C9 of B. oleracea and is located in regions of the B. oleracea genome showing synteny to A. thaliana chromosome 5. BoFRIa is located on C3 and BoFRIb on C9. The copy of FRI on C2 has been lost.