Characterisation and molecular mapping of leaf rust and stripe rust resistance in wheat

Abstract

This investigation was carried out for the characterisation and chromosomal locations of resistance to rust diseases in common wheat and durum wheat recombinant inbred line (RIL) populations. A new seedling stripe rust resistance gene (tentatively named YrAW10) was identified in common wheat landrace Aus27696. This gene is effective against both pre-2002 and post-2002 Australian Puccinia striiformis f. sp. tritici (Pst) pathotypes. YrAW10 was located in 3BL-A02-FL-0.22 deletion bin of chromosome 3B and was flanked by SNP markers KASP_13376 and KASP_8775. Yr29/Lr46-linked marker SNPLr46G22 indicated the presence of this gene in Aus27696.

The presence of Lr16 was confirmed on the basis of infection type produced by Aus91433 and controls (Thatcher + Lr16 and Exchange) against Puccinia triticina (Pt) pathotype 104-1,3,4,6,7,8,9,10,12+Lr37 and linked marker location in the short arm of chromosome 2B. Lr16 was not effective against the Pt pathotypes used in field study. Genotype C16.14 was proved to carry at least two adult plant resistance (APR) genes located on chromosomes 1D and 3B through iSelect 90K SNP based selective genotyping of C16.14/Aus91433 RILs. The chromosome 3B located resistance was proved to be Lr74 through genotyping of markers closely linked with this gene.

In addition to Yr29/Lr46, two other consistent QTL for stripe resistance were detected in Arrivato/Bansi RIL population through DArTseq mapping. QYr.sun-1BS.1 corresponded to Yr24 and QYr.sun-1BS.2 was temporarily named YrAr. Both of these genes produced intermediate responses when present alone. Two QTL located on different linkage groups of chromosome 2B were identified in addition to Lr46/Yr29. QLr.sun-2B.1 appeared to be either a new gene or an allele of Lr16.

Aus27506 was shown to carry QLr.sun-2D in addition to Lr46 and QLr.sun-2B was contributed by Aus27229 in Aus27506/Aus27229 population. QLr.sun-2D and QLr.sun-2B appears to be new loci. Comparison of chitin accumulation in the flag leaves with the performance of QTL indicated that combination of two QTL prevent the fungal growth resulting in low disease severity.