Application and evaluation of genomic selection for improving fusarium head blight resistance and lowering deoxynivalenol accumulation in two-row malting barley
To develop genomic tools that will improve the selection process for the development of fusarium head blight (FHB) resistant and low deoxynivalenol (DON) barley varieties.
Fusarium head blight, caused by Fusarium graminearum, remains the most destructive disease of barley. Associated mycotoxins such as deoxynivalenol (DON) reduce quality of grains and such are strongly regulated by domestic and export markets. Strict limits set by both animal feed and malting and brewing industries which restrict sales and reduce profits of barley producers. Breeding for FHB resistance has been a primary goal of western Canadian barley breeders since the mid 90’s. Over the past two decades the situation for this disease has worsened through westward spread into the major barley growing regions of western Canada. Breeding has been progressive but slowed by limitations of inadequate resistance sources, requirements for large disease nurseries with high labour requirements, and demand for many mycotoxin assays. FHB resistance genetics for barley is further complicated by fact that it is quantitatively controlled (many genes of small effect), where immunity has not been identified.
New biotechnological tools are now at disposal of plant breeders that may facilitate breeding in ways that were not possible in previous decades. This project made use of molecular markers which covered the immense barley genome (5 Gb, or approximately 2X the size human genome) for use in genomic prediction of FHB and DON in two-row barley. A large genomic panel was assembled primarily using elite breeding materials from western Canadian breeding programs with addition of genetics from additional diversified sources. This set was evaluated for FHB reaction and DON content in 3 FHB nurseries across Manitoba over 2 years. Likewise 4 bi-parental populations of differential resistance sources were evaluated for predictive modelling. An Illumina iScan instrument was used to genotype this set with a 50K SNP microarray. This technology recorded significant molecular polymorphism and thus high applicability within Canadian breeding programs. Association mapping analysis confirmed that FHB and DON to likely be under control of multiple genes of minor effects. Through usage of these genome-wide molecular markers, moderate prediction values for FHB and DON were possible. It is demonstrated that the Illumina 50K SNP barley microarray is a useful tool for Canadian barley breeders to make selection with genomic information alone and in absence of expensive field testing. While field evaluation will always be required to verify the realized level of resistance in breeding materials, such technology could be highly useful in pre-selection to increase the total number of crosses that could be evaluated within a year. Overall, this technology is anticipated to assist breeders in developing FHB resistant two-row barley varieties and indicates high potential for use in breeding for other complex characters.