Publication
Virulence Profiles and Genome-Wide Association Study for Ascochyta lentis Isolates Collected from Australian Lentil-Growing Regions
Publisher:
Scientific Societies
Date:
08-2023
DOI:
10.1094/PHYTO-10-22-0397-R
Abstract: Ascochyta lentis, the causal organism of ascochyta blight of lentil (Lens culinaris L.), has been shown to produce an avirulence effector protein that mediates ascochyta blight (AB) resistance in certain lentil cultivars. The two known forms of the effector protein were identified from a biparental mapping population between isolates that have reciprocal virulence on PBA Hurricane XT and Nipper. The effector AlAvr1–1 was described for the PBA Hurricane XT–avirulent isolate P94–24 and AlAvr1–2 characterised in the PBA Hurricane XT-virulent isolate AlKewell. Here, we performed a genome-wide association study (GWAS) to identify other loci associated with AB for a differential set of lentil cultivars from a erse panel of isolates collected in the Australian lentil growing regions from 2013 to 2020. The chromosome 3 AlAvr1 locus was strongly associated with the PBA Hurricane XT, Indianhead and Nipper disease responses but one other genomic region on chromosome 11 was also associated with the Nipper disease trait. Our results corroborate the earlier work that identified the AlAvr1 locus, for field-collected isolates that span the period prior to release and after widespread adoption of PBA Hurricane XT. A multiplex PCR assay was developed to differentiate the respective genes AlAvr1–1 and AlAvr1–2, to predict PBA Hurricane XT avirulence and pathotype designation in the ersity panel. Increasing numbers of the PBA Hurricane XT–virulent pathotype 2 isolates across that time indicates strong selection for isolates with the AlAvr1–2 allele. Furthermore, one other region of the A. lentis genome may contribute to the pathogen-host interaction for lentil AB.