P-282 - Identification of leaf rust resistance loci in hard winter wheat using genome-wide association mapping

Tuesday, August 5, 2025

9:30 AM - 10:15 AM HST

Location: Exhibit Hall 3

Presenting Author(s)

MA

Meriem Aoun

Oklahoma State University
Stillwater, Oklahoma, United States

Author(s)

PA

Philip Adepoju

Oklahoma State University
Stillwater, Oklahoma, United States
IL

Indira Priyadarshini Lakkakula

Graduate Student
Kansas State University
Manhattan, Kansas, United States
BC

Brett F. Carver

Rgts Prof/Enwd Ch
Oklahoma State University
Stillwater, Oklahoma, United States
RS

Rajat Sharma

Graduate Research Assistant
Oklahoma State University
Stillwater, OK, USA
PS

Paul St. Amand

USDA-ARS Hard Winter Wheat Genetics Research Unit
Manhattan, Kansas, United States
AB

Amy Bernardo

USDA-ARS Hard Winter Wheat Genetics Research Unit
Manhattan, Kansas, United States
GB

Guihua Bai

USDA-ARS Hard Winter Wheat Genetics Research Unit
Manhattan, Kansas, United States
AA

Anju Maan Ara

Graduate Research Assistant
Oklahoma State University
Stillwater, Oklahoma, United States

Abstract Text: Leaf rust, caused by the fungus Puccinia triticina, remains a destructive wheat disease throughout the U.S. Great Plains and beyond. This study aims to 1) identify novel sources of leaf rust resistance in contemporary hard winter wheat (HWW) and 2) dissect the genetic basis underlying leaf rust resistance in HWW. A panel of 619 elite breeding lines and varieties from the Oklahoma State University wheat breeding program were evaluated for leaf rust response at the seedling stage against five races in the greenhouse and the adult plant stage in four field environments in Oklahoma. This wheat panel was genotyped using genotyping by sequencing (GBS) and markers linked to 13 known leaf rust resistance (Lr) genes: Lr18, Lr19, Lr21, Lr24, Lr34, Lr37, Lr42, Lr57, Lr46, Lr67, Lr68, Lr77, and Lr78. A total of 34,357 single nucleotide polymorphism markers derived from GBS, markers linked to Lr genes, and phenotypic data were used in a genome-wide association study (GWAS) to identify markers associated with leaf rust response. Phenotyping at the seedling stage showed that 32-47% of the genotypes were resistant, while higher frequencies of resistant genotypes were observed at the adult plant stage in field environments. GWAS identified genomic regions harboring loci for leaf rust resistance across multiple tests on chromosome arms 1DS, 2BS, 6BS, and 7AS. These identified loci will enable the development of molecular markers for use in marker-assisted selection to enhance leaf rust resistance in wheat.