Invited Presenter

Ahmed Charif ^1,2, Tatiana Danilova ¹, Fang Wang ^1,2, Navin Shrestha ^1,2, Yueqiang Leng ³, Shaobin Zhong ⁴, Zhao Jin ⁵, Katherine Frels ², Stephen Wegulo ⁶, Steven Xu ⁷, Elias Elias ⁵, Mike Giroux ⁸, Andrew Green ⁵, and Xiwen Cai ^1,2
1. USDA-ARS, Wheat, Sorghum & Forage Research Unit, Lincoln, NE 68583, USA
2. Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE 68583, USA
3. Department of Plant Pathology, Microbiology and Biotechnology, North Dakota State University, Fargo, ND 58108, USA
4. USDA-ARS, Cereal Disease Laboratory, St. Paul, MN, USA
5. Department of Plant Sciences, North Dakota State University, Fargo, ND 58108, USA
6. Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583, USA
7. USDA-ARS, Crop Improvement and Genetics Research Unit, Western Regional Research Center, Albany, CA 94710, USA
8. Plant Sciences & Plant Pathology Department, Montana State University, Bozeman, MT 59717, USA
Corresponding Author: PH: 402-326-4055; Email: xiwen.cai@usda.gov

Cai, Xiwen

xiwen.cai@usda.gov

Fusarium head blight (FHB) has been a constant threat to wheat and barley production over last few decades due to the constraint of disease control tactics in both host and pathogen. In addition, the complex quantitative inheritance of native FHB resistance has limited the efficacy of the resistance genes in breeding. Here we report introgression and deployment of a novel Th. elongatum-derived FHB resistance gene across several U.S. wheat market classes and in barley. In 2003, we found that Th. elongatum chromosome 7E conferred significant resistance to FHB in the ‘Chinese Spring’ (CS) wheat background. Using an effective genomics-enabled chromosome engineering pipeline, we later integrated the 7E-derived resistance gene into the wheat B subgenome by inducing meiotic homoeologous recombination between 7B and 7E. Out of 36 7B-7E recombinants, a line carrying the smallest terminal segment of 7EL (i.e. 7BS·7BL-7EL) exhibited significant FHB resistance similar to the CS disomic substitution line 7E(7B) and was released as ‘WGC002’ (PI 702949) in 2023. The resistance gene mapped to a 30 Mbp segment in the terminal region of 7EL and designated Fhb7^The2, which differs from two other known Fhb7 alleles at 12 SNP loci. Co-dominant PACE markers diagnostic for Fhb7^The2 were developed and effectively used for Fhb7^The2 introgression in diverse wheat genetic backgrounds. To date, we have incorporated Fhb7^The2 into adapted hard red spring wheat (HRSW), hard red winter wheat (HRWW), and durum wheat backgrounds and developed multiple FHB-resistant HRSW, HRWW, spring and winter durum introgressions containing Fhb7^The2 using a marker-assisted breeding pipeline. Fhb7^The2 showed a typical monogenic-like inheritance, facilitating utilization of Fhb7^The2 in molecular breeding. When pyramided with major FHB resistance genes from Sumai 3, PI 277012, and Frontana, Fhb7^The2 contributed additive effects. Additionally, we have been engineering barley chromosome 7H and Th. elongatum chromosome 7E in the wheat genetic background using ph1b mutant and developed several 7HS·7HL-7EL recombinants containing Fhb7^The2 on the terminal segment of 7EL. The 7HS·7HL-7EL recombinants with a small 7EL terminal segment containing Fhb7^The2 in the wheat background will be introduced into the barley genome by wide hybridization and marker-assisted backcrossing breeding strategy. Collectively, Fhb7^The2 confers exceptional monogenic-like resistance with additive effect to other FHB resistance genes in both common and durum wheat and potentially elevates resistance of barley to FHB as well.

© Copyright 2026 by individual authors. All rights reserved. No part of this abstract or paper publication may be reproduced without prior permission from the applicable author(s).