Abstract
Among the rust diseases, leaf rust of wheat caused by Puccinia triticina, is the most prevalent worldwide and causes significant yield losses. This study aimed to determine the genomic location of loci that control adult plant resistance (APR) to leaf rust in the pre-Green Revolution landrace accession, Aus27506, from the “Watkins Collection”. An Aus27506/Aus27229-derived F7 recombinant inbred line (RIL) population was screened under field conditions across three cropping seasons and genotyped with the iSelect 90K Infinium SNP bead chip array. One quantitative trait loci (QTL) on each of the chromosomes 1BL, 2B and 2DL explained most of the leaf rust response variation in the RIL population, and these were named QLr.sun-1BL, QLr.sun-2B and QLr.sun-2DL, respectively. QLr.sun-1BL and QLr.sun-2DL were contributed by Aus27506. QLr.sun-1BL is likely Lr46, while QLr.sun-2DL appeared to be a new APR locus. The alternate parent, Aus27229, carried the putatively new APR locus QLr.sun-2B. The comparison of average severities among RILs carrying these QTL in different combinations indicated that QLr.sun-2B does not interact with either of the other two QTL; however, the combination of QLr.sun-1BL and QLr.sun-2DL reduced disease severity significantly. In planta fungal quantification assays validated these results. The RILs carrying QLr.sun-1BL and QLr.sun-2DL did not differ significantly from the parent Aus27506 in terms of resistance. Aus27506 can be used as a source of adult plant leaf rust resistance in breeding programs.
Highlights
The leaf rust resistant landrace Aus27506 was selected from the “Watkins Collection” [14] and crossed with the moderately susceptible landrace Aus27229
A recombinant inbred line (RIL) population consisting of 106 RILs (F6:7 ) was developed
These results indicated the absence of seedling and intermediate stage leaf rust resistance in both parents
Summary
Henn), is an important disease of wheat. This rust pathogen is common across a range of geographical environments [1] and was introduced into Australia by early migrant settlers [2]. Several subsequent introductions, combined with the evolution of P. triticina (Pt) pathotypes in Australia, have defeated many of the available leaf rust resistance genes. After 25 years of deployment, Lr24 was overcome in South Australia in 2000 due to the evolution of virulence in Pt pathotype 104-1,2,3,(6),(7),.
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