Dear CAIGE Colleagues:
Laura Espinosa and Nick Fradgley presented a poster in the 2025 Breeding Horizons workshop held at the University of Queensland:
Uncovering genetic architectures of novel resistances for stripe rust disease in CAIGE bread wheat
Abstract
The CIMMYT Australia ICARDA Germplasm Exchange (CAIGE) project has generated substantial amount of data on foliar and root disease resistance in bread wheat (Triticum aestivum) and barley (Hordeum vulgare) in Australia, using breeding material from CIMMYT and ICARDA over many years. Bread wheat lines were screened by pathologists for stripe (yellow) rust (caused by Puccinia striiformis f. sp. tritici), leaf rust (P. triticina) and stem rust (P. graminis f. sp. tritici), septoria blotch (both Zymoseptoria tritici and Parastagonospora nodorum) and yellow spot/tan spot/yellow leaf spot (Pyrenophora tritici-repentis). A portion of these lines was also assessed for the root diseases crown rot (Fusarium pseudograminearum) and root-lesion nematode (RLN; Pratylenchus thornei), with resistance and tolerance evaluated for RLN only. Comprehensive genetic characterisation of CAIGE material using the Infinium Wheat Barley 40K SNP array (Keeble-Gagnère et al., 2021) has enabled long-term investigation of the genetic architecture of multiple disease resistances.
Similarly to analysis of multi-environment yield trials, Factor Analytic Linear Mixed Models (Smith et al., 2021) have proven useful for analysing wheat stripe rust resistance data over years. In this work, we used genotypic data and yellow rust disease scores from 863 bread wheat lines screened at PBI (Cobbitty) and AgVic (Horsham) between 2022 and 2024. These wheat lines were also included in yield trials conducted by private breeding collaborators across the western, southern and northern Australian cereal cropping regions during the same period.
Classifying environments with the iClass system has also provided insights how the pathogen races have evolved in recent years. Genome wide association of genetic marker data with data within each iClass environment type/pathotype further reveals which genetic markers or associated known resistance genes are novel in CAIGE material and are still effective against recent pathogen races.
So far, this work has focused on stripe rust, but future efforts will investigate the resistance responses of the CAIGE lines to other high-priority foliar and root diseases that have been phenotyped as part of the CAIGE project.
Kind regards on behalf of the CAIGE team
Julie Nicol