Brunner S

Hoxla S

Keller B

Lagudah, E

McIntosh RA

Zhang P

English

Sydney eScholarship

The inhibitor of Pm8 in certain 1BL.1RS wheat genotypes   McIntosh RA1, Zhang P1, Lagudah E2, Brunner S3, Keller B3, Hoxla S1  1University of Sydney Plant Breeding Institue Cobbitty, Camden, NSW 2570, Australia,  2CSIRO Plant Industry, Canberra, ACT 2601, Australia, 3 Institute of Plant Biology, University of Zürich, Switzerland  Pm8 for resistance to powdery mildew is one of the disease response genes carried by the widely used 1BL.1RS chromosome with 1RS derived from Petkus rye. However, Pm8 when challenged by avirulent Blumeria graminis tritici cultures is not expressed in all wheat genetic backgrounds. According to Ren et al. the dominant suppressor of Pm8 is located in close proximity to the Gli-A1/Glu-A3 loci on chromosome 1AS. These loci are closely linked with the Pm3 locus. Different selections of Veery and Bobwhite vary in response to powdery mildew even though they have the 1BL.1RS translocation. F2-derived F5 populations developed from crosses between resistant and susceptible (suppressed) selections of each cultivar segregated for response to powdery mildew and resistance in some segregating lines was recessive (dominant inhibition). These populations were subjected to analysis with functional markers for Gli-A3 and Pm3. We have shown that wheats lacking a Pm3 powdery mildew response either possessed a functional transcribed allele (e.g. Chinese Spring which lacked a known Pm3 resistance specificity), a terminated allele, or were null. Our analyses indicate that lines with functional alleles of Pm3, including the Chinese Spring allele, show suppression of Pm8, which we presume to be an orthologue of Pm3. We are developing transient assays to test our prediction that Pm8 will not function when combined with functional Pm3 alleles, and also combining the translocation in lines with Pm3 alleles. We know of no wheat genotype with 1BL.1RS and a named Pm3 resistance allele. This work has important implications in understanding the commonly reported phenomenon of resistance gene suppression (or dilution) in wheat wide crosses, as well as the actual genetic basis of suppression. It also raises the issue of functions of different alleles transformed into a single wheat genotype.            

The inhibitor of Pm8 in certain 1BL.1RS wheat genotypes

https://ses.library.usyd.edu.au/bitstream/2123/3413/1/P138.pdf

The inhibitor of Pm8 in certain 1BL.1RS wheat genotypes

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