Abstract
Fusarium Head Blight (FHB) has emerged in spring wheat production in Pacific Northwest during the last decade due to factors including climate changes, crop rotations, and tillage practices. A breeding population with 170 spring wheat lines was established and screened over a 2-year period in multiple locations for FHB incidence (INC), severity (SEV), and deposition of the mycotoxin, deoxynivalenol (DON). A genome-wide association study suggested that the detectable number of genetic loci and effects are limited for marker-assisted selection. In conjunction with the success of breeding on FHB resistance in other programs, genomic selection (GS) was suggested as a better option. To evaluate the prediction accuracy of GS in the current breeding population, we conducted a variety of validations by varying proportions of testing populations and cohorts based on both FHB resistance and market class, including soft white spring (SWS), hard white spring (HWS), and hard red spring (HRS). We found that INC had higher heritability, higher correlation across years and locations, and higher prediction accuracy than SEV and DON. Prediction accuracy varied among the scenarios that restricted the testing population to a certain cohort. For a small set of newly developed or introduced lines (<17), prediction accuracy will be about 60% if the lines have similar genetic relationships as those among the current 170-line training population. However, we expect a lower prediction accuracy if new lines are selected for a specific characteristic, such as FHB resistance or market class. With the exception of DON in the SWS lines, the current training population is capable of making reasonably accurate predictions for FHB-resistant lines in most of the major market classes. For SWS, adding more lines or further phenotyping is required to improve prediction accuracy. These results demonstrate the potential and challenges of GS, especially for developing FHB-resistant varieties in the SWS market class.
Highlights
Fusarium head blight (FHB) is a devastating disease that affects corn and small grain crops such as wheat in humid conditions (Schroeder and Christensen, 1963; Wang et al, 1982; Snijders, 1990)
This study suggested that FHB resistance in spring wheat is controlled by a relatively large number of quantitative trait loci (QTL) with small effects
A total of 170 spring wheat cultivars and elite lines developed from the breeding programs in the Pacific Northwest (PNW) and CIMMYT were used in this study
Summary
Fusarium head blight (FHB) is a devastating disease that affects corn and small grain crops such as wheat in humid conditions (Schroeder and Christensen, 1963; Wang et al, 1982; Snijders, 1990). FHB causes shriveled kernels, significant yield losses, and deposition of the mycotoxin, deoxynivalenol in the infected seeds, which renders the grain unsuitable for human consumption and animal feed (McMullen et al, 1997). Most of the wheat cultivars currently grown in the PNW are susceptible to FHB and, when infected, often produce high levels of deoxynivalenol (Marshall, 2014). Development of FHB-resistant wheat cultivars for the region is critically needed to reduce the impending negative consequences, including reduced crop yield and quality and increased costs for fungicides
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