P-283 - Identification of novel genetic resistance loci for leaf and stripe rusts in soft red winter wheat in the southeast US

Monday, August 4, 2025

3:45 PM - 4:30 PM HST

Location: Exhibit Hall 3

Presenting Author(s)

BB

Bochra Amina Bahri, PhD

Associate Professor, Turfgrass and Forage Pathology
University of Georgia
Griffin, GA, USA

Author(s)

JB

John Bagwell

Department of Forestry and Environmental Resources
Raleigh, North Carolina, United States
MS

Madhav Subedi

Breeding Insight, Cornell University
Ithaca, New York, United States
SS

Suraj Sapkota

USDA-ARS, Small Grains and Potato Germplasm Research Unit
Aberdeen, Idaho, United States
BG

Bikash Ghimire, PhD (he/him/his)

Assistant Professor
University of Georgia
Athens, Georgia, United States
BL

Benjamin Lopez

Department of Crop and Soil Sciences, University of Georgia
Griffin, Georgia, United States
JB

James W. Buck, PhD

Professor
Department of Plant Pathology, University of Georgia
Griffin, Georgia, United States
MM

Mohamed Mergoum

Department of Crop and Soil Sciences, University of Georgia
Griffin, Georgia, United States

Abstract Text: Leaf rust (LR), caused by Puccinia triticina, and stripe rust (YR), caused by Puccinia striiformis, are damaging wheat diseases worldwide that are typically managed using resistant cultivars. Although hundreds of resistance (R) genes for LR and YR have been identified, rust pathogens are quickly overcoming the introduced R genes in the US southeast. We conducted a genome-wide association study to identify putative LR and YR resistance loci in a panel of 266 soft red winter wheat genotypes. LR and YR field disease severities were scored on two replicates in Plains, GA and Williamson, GA from 2019-2023 (Feekes stage 10.5). LR and YR infection types were also measured on three leaf-stage seedlings in the greenhouse (Feekes stage 1.3). We discovered 26 quantitative trait loci (QTL), including ten major QTL explaining >10% of phenotypic variation (PV), using at least two of the five GAPIT models (BLINK, CMLM, FarmCPU, GLM, MLM). Notably, QTL QLrYr-2A.1, linked to SNP S2A_20855466, had the highest PV (30.76%) detected in Plains and Williamson for response to both rust pathogens, and in the greenhouse (PV = 12.9%) for LR. Using the Chinese Spring Reference Genome Version 1.0, we detected six candidate genes overlapping our major QTL: a lysine histidine transporter, a disease resistance protein, an apoplastic protein, a W2 domain-containing protein, and a Myb-like DNA-binding domain family, involved in biotic and abiotic stresses. The ten major QTL are presumed to be novel as they did not overlap with any known R genes, underscoring their potential in wheat breeding programs.