Submitted to: Australian Journal of Agricultural Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/10/2003
Publication Date: 12/1/2003
Citation: Raman, H., Karakousis, A., Moroni, J.S., Raman, R., Read, B.J., Garvin, D.F., Kochian, L.V., Sorrells, M.E. 2003. Development and allele diversity of microsatellite markers linked to the barley aluminum tolerance gene ALP. Australian Journal of Agricultural Research. 54:1315-1321. Interpretive Summary: A major factor that limits crop production on the acidic soils of the world is the presence of toxic levels of aluminum. Aluminum toxicity prevents normal root system development, leading to reduced productivity. The barley variety Dayton contains a gene that can reduce root damage caused by aluminum toxicity, resulting in healthier plants when grown on acidic soils. This study sought to develop a rapid and simple DNA-based testing method for detecting the presence of this gene. Several DNA markers associated with the gene were successfully identified. By examining the DNA of a given barley plant for the presence of the two DNA markers most closely associated with this gene, it should be possible to predict whether the gene is present with greater than 99% accuracy. The markers will be useful to barley breeders seeking to use this gene in their breeding programs because it allows selection for the gene without the need to undertake more time-consuming methods for detecting its presence. Improving aluminum tolerance in barley not only will result in higher crop yields for producers growing the crop on acidic soils but can also reduce lime applications to the soil, providing yet another financial benefit to the producer.
Technical Abstract: The utilization of barley cultivars tolerant to aluminum (Al) is one of the most economical strategies for expanding barley production on acidic soils. A gene conferring Al tolerance in the barley cultivar "Dayton", Alp, has previously been mapped to the long arm of chromosome 4H with RFLP markers. To increase the ease by which marker-assisted selection can be conducted for Alp, we sought to identify microsatellite markers linked to this gene. Several such markers that flank Alp were identified in a mapping population from a cross between "Dayton" and "Harlan Hybrid". The most tightly linked markers, HVM68 and Bmag353, flank Alp and are 5.3 cM and 3.1 cM from this locus, respectively. The linkage between Bmag353 and Alp was validated in a separate F3 population derived from a cross involving "Dayton". Allele diversity for the three most tightly linked microsatellite markers was evaluated among 37 barley genotypes used in Australian barley breeding programs. The high levels of polymorphism detected among the genotypes with the markers indicates that the microsatellite markers, especially Bmag353 and HVM68, will be broadly useful for marker assisted selection of Alp in breeding programs seeking to improve Al tolerance.