Genetic architecture of adult-alant resistance to stripe rust in a bread wheat (Triticum aestivum L.) association panel

Authors: ATSBEHA, GENET - ADAMA SCIENCE AND TECHNOLOGY UNIVERSITY; MEKONNEN, TILAHUN - ADDIS ABABA UNIVERSITY; KEBEDE, MULUGETA - ADDIS ABABA UNIVERSITY; HAILESELASSIE, TEKLEHAIMANOT - ADDIS ABABA UNIVERSITY; Goodwin, Stephen - Steve; TESFAYE, KASSAHUN - ADDIS ABABA UNIVERSITY

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2023
Publication Date: 12/7/2023
Citation: Atsbeha, G., Mekonnen, T., Kebede, M., Haileselassie, T., Goodwin, S.B., Tesfaye, K. 2023. Genetic architecture of adult-alant resistance to stripe rust in a bread wheat (Triticum aestivum L.) association panel. Frontiers in Plant Science. https://doi.org/fpls.2023.1256770.

Interpretive Summary: Stripe rust or yellow rust, caused by the fungus Puccinia striiformis f. sp. tritici, is a severe disease of wheat worldwide. It is the most common disease in the cooler highlands of Ethiopia, causing up to 100% wheat yield loss. To test for new sources of resistance against Ethiopian populations of the fungus, genome-wide association analysis was carried out on 178 bread wheat germplasm accessions at the adult-plant stage in three locations. Heritability of the considered traits was high, implying the presence of yellow rust resistance genes in the panel. Association analysis identified 148 chromosomal locations that were significantly associated with yellow rust adult plant resistance. Most of these were located at the same positions as previously reported genes for resistance against this pathogen, but 12 of the discovered chromosomal locations were not reported previously and may represent novel genes for stripe rust resistance in Ethiopia. These results will be of interest to wheat breeders who could use the associated molecular markers in selection to increase the level of resistance to stripe rust in Ethiopia and other countries.

Technical Abstract: Stripe rust or yellow rust caused by Puccinia striiformis f. sp. tritici, is a severe disease of wheat worldwide. It is the most common disease in the colder highlands of Ethiopia, causing up to 100% wheat yield loss. Use of host genetic resistance is one of the most effective and durable management techniques for controlling the disease. In this study, genome-wide association analysis employing 6,788 polymorphic SNP markers obtained by genotyping-by-sequencing (GBS) was carried out on 178 bread wheat germplasm accessions to identify effective yellow rust resistance genes. The association panel's phenotypic resistance to stripe rust was assessed at the adult-plant stage in three different locations. Phenological, yield, yield-related and morphological traits were recorded. The genome association and prediction integrated tool (GAPIT) was used to identify marker-trait associations. The broad-sense heritability for the considered traits ranged from 74.5 to 88.6%, implying the presence of yellow rust resistance genes in the panel. The overall linkage disequilibrium (LD) declined within average physical distance of 31.44 Mbp at r2 = 0.2. Marker-trait-association (MTA) analysis identified 148 loci that were significantly (p = 0.001) associated with yellow rust adult plant resistance. The majority of the identified resistance QTLs were located on the same chromosomes as previously reported QTLs that were found on chromosomes 1A, 1B, 1D, 2A, 2B, 2D, 3A, 3B, 3D, 4A, 4B, 4D, 5A, 5B, 6A, 6B, and 7A and 7D. However, 12 of the discovered MTAs were not previously documented in the wheat literature, suggesting that they may represent novel loci for stripe rust resistance. Focusing on the QTL regions in the IWGSC RefSeq Annotation v2 identified crucial disease resistance-associated genes that are key in plant defense mechanisms against pathogen infections. The association panel possessed significant P. striiformis resistance alleles that could be used to advance wheat resistance to populations of this pathogen in Ethiopia. The detected QTLs will be helpful for marker-assisted breeding of wheat to increase resistance to stripe rust.