|Kolmer, James - Jim|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2008
Publication Date: 9/1/2008
Citation: Kolmer, J.A., Singh, R.P., Garvin, D.F., Viccars, L., William, H.M., Huerta-Espino, J., Ogbonnaya, F.C., Raman, H., Orford, S., Bariana, H.S., Lagudah, E.S. 2008. Analysis of the Lr34/Yr18 Rust Resistance Region in Wheat Germplasm. Crop Science. 48(5):1841-1852. Interpretive Summary: A molecular marker was developed that can be used to determine the presence or absence of the leaf rust resistance gene Lr34 in wheat. This gene is critical since it is responsible for long lasting resistance in wheat to the leaf rust pathogen Puccinia triticina. The marker can be used to test for the presence of this gene without having to test adult wheat plants of wheat with leaf rust. A large number of wheats from around the world were tested with the maker to determine the presence of Lr34 in these wheats. Lr34 was most common in US spring wheats developed for Minnesota, North Dakota, and South Dakota. Lr34 was also commonly found in wheat cultivars from CIMMYT. These results can be used by wheat breeders to select wheat cultivars with Lr34 for use in crossing and also to more easily develop new cultivars with Lr34, and thus develop new cultivars with better leaf rust resistance.
Technical Abstract: An insertion/deletion size variant located at the csLV34 locus on chromosome 7D within an intron sequence of a sulphate transporter-like gene tightly linked to the Lr34/Yr18 dual rust resistance was used to examine a global collection of wheat cultivars, landraces and D genome containing diploid and polyploid species of wheat relatives. Two predominant allelic size variants, "csLV34a" and "b" were found among the wheat cultivars and showed disparate variation in different wheat growing zones. A strong association was observed between the presence of Lr34/Yr18 and csLV34b allele and the simultaneous occurrence of established sources of Lr34/Yr18 with csLV34a allele was rare. All landraces with the exception of those from China were predominantly of the csLV34a type. Only one size variant, csLV34a, was detected among the diploid and polyploid D genome containing species, implicating csLV34b as having arose subsequent to hexaploid bread wheat synthesis. The lineage of the csLV34b allele associated with Lr34/Yr18 in a significant proportion of modern wheat cultivars from North and South America, CIMMYT, Australia and Russia was tracked back to the older cultivars Mentana and Ardito developed in Italy by Nazareno Strampelli in the early 1900s.