Submitted to: Molecular Breeding
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/25/2006
Publication Date: 10/20/2006
Citation: Zhou, L., Bai, G., Ma, H., Brett, C.F. 2006. Quantitative trait loci for aluminum resistance in wheat. Molecular Breeding. 19:153-161. Interpretive Summary: Aluminum (Al) toxicity is one of the major limiting factors for wheat production in acid soils. Genetic improvement of Al tolerance is one of the most cost-effective solutions to improve wheat productivity. The objectives of the present study were to identify wheat genes for Al-tolerance and molecular markers linked to the genes for marker-assisted breeding. A mapping population of 192 F6 recombinant inbred lines (RILs) was derived from the cross Atlas 66/Chisholm. This population was tested for Al-tolerance by measuring root growth rate during Al treatment in Al-containing nutrient solution and root response to hematoxylin stain after Al treatment. Results confirmed the gene on chromosome 4DL that was previously identified in another mapping population and also found a new gene on chromosome 3BL. This gene has a smaller effect on Al resistance than the one on 4DL. Molecular markers closely linked to the Al tolerance genes on 4DL and 3BL were identified and have potential to be used for high-throughput, marker-assisted selection in wheat breeding programs.
Technical Abstract: Quantitative trait loci (QTLs) for wheat resistance to aluminum (Al) toxicity were analyzed using simple sequence repeats (SSRs) in a population of 192 F6 recombinant inbred lines (RILs) derived from a cross between an Al-resistant cultivar, Atlas 66 and an Al-sensitive cultivar, Chisholm. Wheat reaction to Al was measured by relative root growth and root response to hematoxylin stain in nutrient-solution culture. After screening 1028 SSR markers for polymorphisms between the parents and bulks, we identified two QTLs for Al resistance in Atlas 66. One major QTL was mapped on chromosome 4D that co-segregated with the Al-activated malate transporter gene (ALMT1). Another minor QTL was located on chromosome 3BL. Together, these two QTLs accounted for about 57% of the phenotypic variation in hematoxylin staining score and 50% of the variation in net root growth (NRG). Expression of the minor QTL on 3BL was suppressed by the major QTL on 4DL. The two QTLs for Al resistance in Atlas 66 were also verified in an additional RIL population derived from Atlas 66/Century. Several SSR markers closely linked to the QTLs were identified and have potential to be used for marker-assisted selection (MAS) to improve Al-resistance of wheat cultivars in breeding programs.