Fusarium Head Blight and Rust Diseases in Soft Red Winter Wheat in the Southeast United States: State of the Art, Challenges and Future Perspective for Breeding.

Mohamed Mergoum,Bochra A Bahri,Alfredo D Martinez-Espinoza,Suraj Sapkota,Bikash Ghimire,James W Buck

doi:10.3389/fpls.2020.01080

Mohamed Mergoum, Bochra A Bahri + Show 4 more

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https://doi.org/10.3389/fpls.2020.01080

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Abstract

Among the biotic constraints to wheat (Triticum aestivum L.) production, fusarium head blight (FHB), caused by Fusarium graminearum, leaf rust (LR), caused by Puccinia triticina, and stripe rust (SR) caused by Puccinia striiformis are problematic fungal diseases worldwide. Each can significantly reduce grain yield while FHB causes additional food and feed safety concerns due to mycotoxin contamination of grain. Genetic resistance is the most effective and sustainable approach for managing wheat diseases. In the past 20 years, over 500 quantitative trait loci (QTLs) conferring small to moderate effects for the different FHB resistance types have been reported in wheat. Similarly, 79 Lr-genes and more than 200 QTLs and 82 Yr-genes and 140 QTLs have been reported for seedling and adult plant LR and SR resistance, respectively. Most QTLs conferring rust resistance are race-specific generally conforming to a classical gene-for-gene interaction while resistance to FHB exhibits complex polygenic inheritance with several genetic loci contributing to one resistance type. Identification and deployment of additional genes/QTLs associated with FHB and rust resistance can expedite wheat breeding through marker-assisted and/or genomic selection to combine small-effect QTL in the gene pool. LR disease has been present in the southeast United States for decades while SR and FHB have become increasingly problematic in the past 20 years, with FHB arguably due to increased corn acreage in the region. Currently, QTLs on chromosome 1B from Jamestown, 1A, 1B, 2A, 2B, 2D, 4A, 5A, and 6A from W14, Ning7840, Ernie, Bess, Massey, NC-Neuse, and Truman, and 3B (Fhb1) from Sumai 3 for FHB resistance, Lr9, Lr10, Lr18, Lr24, Lr37, LrA2K, and Lr2K38 genes for LR resistance, and Yr17 and YrR61 for SR resistance have been extensively deployed in southeast wheat breeding programs. This review aims to disclose the current status of FHB, LR, and SR diseases, summarize the genetics of resistance and breeding efforts for the deployment of FHB and rust resistance QTL on soft red winter wheat cultivars, and present breeding strategies to achieve sustainable management of these diseases in the southeast US.

Highlights

Wheat (Triticum aestivum L.) is a staple food crop grown in 17% of the total world cropping area and contributes towards 18.3% of the global human calorie intake just next to rice (Peng et al, 2011; FAOSTAT, 2018)
Among the five major wheat classes in the United States (US), soft red winter wheat (SRWW) common to the southeast US shares 15–20% of total area and 17% of total production (Vocke and Ali, 2013). This major cereal crop is under continuous threat due to several biotic and abiotic constraints resulting in a significant reduction in grain yield and quality (Limbalkar et al, 2018; Ghimire et al, 2020)
The SRWW cultivar Jamestown developed from the cross between Roane and Pioneer Brand 2691 by the Virginia Agricultural Experiment Station in 2007 is considered as a strong native source of fusarium head blight (FHB) resistance (1BL) and is widely used a donor parent and FHB resistance check in the annual Southern Uniform Winter Wheat Scab Nursery (SUWWSN) (Griffey et al, 2010a; Zhu et al, 2019)

Summary

Introduction

Wheat (Triticum aestivum L.) is a staple food crop grown in 17% of the total world cropping area and contributes towards 18.3% of the global human calorie intake just next to rice (Peng et al, 2011; FAOSTAT, 2018). The development of FHB resistant wheat cultivars is the single most cost-effective and sustainable approach to manage this disease.

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