Submitted to: Wheat Genetics International Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/30/2003
Publication Date: 9/1/2003
Citation: Linkiewicz, A.M., Qi, L.L., Echalier, B., Gill, B.S., Chao, S., Lazo, G.R., Anderson, O.D., Akhunov, E.D., Dvorak, J., Miftahudin. 2003. A two thousand loci physical map of wheat homoeologous group 5. Wheat Genetics International Symposium Proceedings. 3:986-988. Interpretive Summary: Recent findings about the placement of genes expressed in wheat are providing an insight into the organization of the wheat genome. Genes in wheat were tentatively placed on genetic maps constructed from a complex series of screenings against wheat mapping lines. From a larger set of probes used to detect tentative genetic loci, a subset of these were used to detect the presence on chromsomes 5A, 5B, and 5D of wheat. A total of 2,338 loci were mapped to the group 5 chromosomes using 1,052 DNA probes, and were compared to construct a consensus map which including 28 delineated bins on the chromosomes. A relatively higher number of probes were mapped on the 5B genome compared to that of 5A and 5D. The B genome also showed a higher level of duplicated loci. The long arms showed three times more probes than the short arms, and in both arms the distal halves showed a significantly higher number of probes, loci, and duplicated loci than the proximal halves. A good overall colinearity was observed among the three genomes, except for the previously known translocation (5AL/4AL) and a few small pericentric inversion in chromosome 5A. Comparison to related grass species genome of rice demonstrated similar orders of probes along the chromosome, inferring some colinearity between the species.
Technical Abstract: As a part of the NSF-funded Wheat EST Project we mapped 7,000 unigenes in a set of 102 deletion lines (http://wheat.pw.usda.gov/NSF/). We summarized here the results for homoeologous group 5. A total of 2,338 loci were mapped with 1,052 EST probes and used to construct a consensus map including 28 bins. A relatively higher number of ESTs were mapped on the B genome (38%) compared to the A (34%) and D (29%) genomes. The B genome also showed a higher level of duplicated loci (42%). Differences in the level of polymorphism were only partially responsible for these differences. The long arms showed three times more probes than the short arms, and in both arms the distal halves showed a significantly higher number of probes, loci, and duplicated loci tahn the proximal halves. A good overall colinearity was observed among the three genomes, except for the previously known 5AL/4AL translocation and a few small pericentric inversion in chromosome 5A. Statistically significant colinearity was observed between wheat homoeologous group 5 and rice chromosome 12 (88 ESTs), 9 (72 ESTs), and 3 (84 ESTs). This colinearity can be used to infer the order of the wheat ESTs within the bins.