Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2007
Publication Date: 11/20/2007
Citation: Mano, Y., Omori, F., Kindiger, B.K., Takahashi, H. 2007. A linkage map of maize x teosinte zea luxurians and identification of qtls controlling root aerenchyma formation. Molecular Breeding. 295:103-113. 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. For this study, a comparative genome study was initiated to identify the potential to transfer flooding tolerance to corn from a teosinte. A breeding population was generated by crossing a corn inbred line (B73) with a teosinte (Zea luxurians). Segregating individuals obtained from this hybridization were used for a comparative analysis of their genomes and the identification of chromosome regions that may possess genes conferring flooding tolerance. Results of the analysis suggest that genes regulating flooding tolerance in teosinte can be found on chromosomes 1, 5 and 8. The expression and segregation of flooding tolerance in the segregating population, 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 be valuable to maize breeders and geneticists interested in transferring a degree of flooding tolerance to selected maize lines and corn hybrids.
Technical Abstract: One-hundred and ninety five F2 individuals, derived from a cross between maize inbred line B73 x Zea luxurians, were subjected to a 107 SSR marker based QTL analysis for aerenchyma cell formation that covered 1,331 cM across all ten maize and Zea luxurians chromosomes. Composite interval mapping analysis suggest that a single QTL for aerenchyma formation in non-flooding conditions is located on chromosome 2 (designated as Qaer2.06) and explains 9.1 % of the total phenotypic variance. Multiple interval mapping analysis found an additional four QTLs on chromosomes 3 (Qaer3.10), 5 (Qaer5.05-6), 9 (Qaer9.07-8) and 10 (Qaer10.04). These QTL are different than those identified for aerenchyma cell formation in a similar study using the teosinte Zea nicaraguensis. This data suggest that other teosinte carry aerenchyma cell forming loci and that the presence of aerenchyma-forming QTLs from both Z. luxurians and Z. nicaraguensis, may allow a corn breeder to pyramid these genes and develop a maize hybrid exhibiting exceptional aerenchyma development and a high level of tolerance to flooding.