Submitted to: Plant Breeding
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/28/2005
Publication Date: 10/20/2005
Citation: Mano, Y., Muraki, M., Fujimori, M., Takamizo, T., Kindiger, B.K. 2005. Aflp-ssr maps of maize x teosinte and maize x maize: comparison of map length and segregation distortion. Plant Breeding. 124:432-439. Interpretive Summary: Comparing the genomes of corn and a close relative such as teosinte can provide useful information for corn improvement projects focused on transferring advantageous genes within and across species. The detection of differences between similar and dissimilar genomes can also be used to enhance the opportunity to facilitate marker-assisted corn improvement breeding projects. A comparative genome study was initiated to identify the potential for transferring flooding tolerance to corn from teosinte and a flooding tolerant Caribbean flint inbred line. Two breeding populations were generated by crossing a corn inbred line (B64) with a teosinte (Zea mays ssp. huehuetenangensis) and by crossing B64 with a Caribbean flint inbred line (Na4). Segregating individuals obtained form these populations were used for a comparative genetic analysis of their genomes and chromosome regions that may possess genes conferring flooding tolerance. Results of the analysis suggest that the B64 x teosinte population contained regions where gene introgression could be reduced by physical differences between the two genomes. In the B64 x Na4 population, similar distortions were not observed. These data suggest that transferring some genes from teosinte to maize could be limited by genome differences. However, in the case of flooding tolerance, genome distortions in regions possessing such genes were not observed in either population. The expression and segregation of flooding tolerance in the two populations, and the association of molecular markers to various genes controlling this trait, suggest that these genes can be readily transferred to corn by a marker-assisted breeding program. The results of this study will assist maize breeders and geneticists interested in transferring a degree of flooding tolerance to selected maize lines and corn hybrids.
Technical Abstract: A comparison of genetic linkage relationships between maize and teosinte were undertaken following the compilation of two genetic linkage maps. The first map was developed from segregating individuals generated by hybridizing maize inbred line 'B64' with Zea mays ssp. huehuetenangensis teosinte. The second map was developed from segregating individuals generated by hybridizing maize inbred line 'B64' with a maize Caribbean flint inbred line, 'Na4'. Results of the comparative analysis indicate that the level of polymorphism was higher in the B64 x teosinte population than the B64 x Na4 population. In the B64 x teosinte population, a total of 338 AFLP and 75 SSR markers were mapped to ten chromosomes, which covered 1402.4 cM of the potential genome. In the B64 x Na4 population, a total of 340 AFLP and 97 SSR markers were mapped to ten chromosomes, covering 1662.8 cM of the potential genome. Genetic linkage analysis of the molecular markers across the two populations suggests segregation distortion in particular regions of chromosomes 4, 5, and 8 in the B64 x teosinte population and on chromosome 9 in the B64 x Na4 population. Comparison of the two maps revealed that the B64 x teosinte map was 11.5% shorter than the B64 x Na4 map. When a comparison was made for each of the ten chromosomes, map lengths in chromosomes 1, 2, 5, 7 and 10 were shorter in the B64 x teosinte population while chromosome 6 exhibited an 11.5% extension. In addition, genes conferring flooding tolerance in teosinte were confirmed to be associated with chromosomes 4 and 8 in Zea mays ssp. huehuetenangensis, suggesting markers-assisted-selection will be useful in transferring flooding tolerance to maize.