|Lapitan, N L|
Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2004
Publication Date: 10/1/2004
Citation: Randhawa, H.S., Dilbirligi, M., Sidhu, D., Erayman, M., Sandhu, D., Bondareva, S., Chao, S., Lazo, G.R., Anderson, O.D., Miftahudin, Gustafson, J.P., Echalier, B., Qi, L.L., Gill, B.S., Akhunov, E.D., Dvorak, J., Linkiewicz, A.M., Dubcovsky, J., Bermudez-Kandianis, C.E., Greene, R.A., Sorrells, M.E., Wennerlind, E., Anderson, J.A., Peng, J., Lapitan, N.V., Hossain, K.S., Kianian, S.F., Pathan, M.S., Nguyen, H.T., Endo, T.R., Close, T.J., Mcguire, P., Qualset, C.O., Gill, K.S. 2004. Deletion mapping of homoeologous group 6-specific wheat ests. Genetics. 168:677-686. Interpretive Summary: Expressed DNA sequences were taken from 37 cDNA libraries and were physically mapped to specific chromosome regions of wheat homoeologous group 6 chromosomes. We found that the expressed sequences were not scattered from one end to the other of the group 6 chromosomes, but seemed to be clustered in more distal regions of the chromosomes. From our physical map, we were also able to establish the location of group 6 chromosome re-arrangements. This information will be of value to wheat geneticists in map-based cloning of expressed sequences located on wheat homoeologous group 6 chromosomes.
Technical Abstract: In order to localize expressed sequence tags (ESTs) on chromosomes, 882 wheat homoeologous group 6-specific ESTs were identified by physically mapping 7965 wheat EST singletons from 37 cDNA libraries on 21 nullisomic-tetrasomic, 24 ditelosomic, and 101 deletion lines. The 882 ESTs were physically mapped to 26 regions (bins) of group 6 chromosomes flanked by 23 deletion breakpoints. A total of 5154 restriction fragments with an average of 5.84 fragments per EST, were detected. Of these, 2043 loci were localized to group 6 chromosome bins and 806 mapped to others. The number of loci mapped was highest for chromosome 6B and lowest for 6D. Approximately 264 (30%) of the ESTs that detected orthologous loci on all three homoeologs using one restriction enzyme were used to construct a consensus physical map. The physical distribution of both ESTs and recombination was highly uneven on the chromosomes with higher densities in the distal half of the chromosomes. Comparative sequence analysis with the rice genome showed that about 43% of the wheat group 6 ESTs have rice homologs. Fifty-eight percent of these were present on rice chromosome 2 and the remaining were on other chromosomes. Even within each group 6 bin, homologs belonged to up to 11 rice chromosomes. Non-rice chromosome 2 blocks for each wheat group 6 bin were identified with one to six ESTs each. The order of wheat ESTs within the bins was resolved using the corresponding rice contigs.