Scald-resistance gene mapping and breeding
Dr. Aaron Beattie
Assistant Professor, Plant Sciences
University of Saskatchewan
Timeline: April 2014 – March 2018
Alberta Barley funding: project management
Total funding from other partners: $96,052
Benefits for barley farmers
This project will produce malt and feed barley varieties with improved scald resistance (a disease that impacts many Alberta farmers) and improve the financial return of growing barley. Such varieties will contribute to a more stable supply of malting feed barley grain for both the malting and brewing industry and feed industry.
The objectives of this project are to evaluate and map several barley scald resistance genes and to create molecular markers for effective scald resistance genes for use in genetic selection.
As indicated in 2015, TR14150 is a two-row, hulled malting barley line that shows good agronomic performance and malting quality, and it contains scald resistance derived from one of the four bi-parental barley populations we are evaluating (TR08116/SB050739). This line was tested in the 2015 Western Co-operative Two-Row Barley Registration Trial (2RCoop) and continued to show excellent agronomic performance and malt quality. Following a final year of malt evaluation in 2016, if the line continues to show good malt quality it will be put forth for registration in 2017. TR14150 may prove to be a valuable variety for producers in the scald-prone areas of Alberta.
Objectives for the upcoming year
Continue with original objectives
The goals of this project were to produce malt and feed barley varieties with improved scald resistance (a disease that impacts many Alberta farmers) and improve the financial return of growing barley. Such varieties will contribute to a more stable supply of malting feed barley grain for both the malting and brewing industry and feed industry.
Five bi-parental barley populations, each segregating for different scald resistance sources, were used for QTL mapping to identify markers linked to the 5 different sources of scald resistance present in these populations. A single QTL was identified in each population, with QTL being located on chromosomes 3H (TR05384 x Laurel), 4H (TR07110 x 261G2) and 3 co-located QTL on 6H (TR08116 x 145L2, CDC Austenson x RP41T1, CDC Meredith x RP40Y5). TaqMan assays were developed for each resistance.
Exome capture was conducted on the three populations with resistance genes (RP41T1, RP40Y5, 145L2) co-located on chromosome 6H. A bulked-segregant approach was used with the exome capture which returned an average of 22 million 130 nucleotide-long sequence reads (2.9 billion nucleotides) per genotype. The “coding” region of the barley genome comprises approximately 61 megabases, suggesting a sequencing depth of 45X.
An examination of genes captured within the narrow interval surrounding RhNZ6SNP7 (the TaqMan marker underlying the QTL peak for these three resistance genes) revealed the presence of two NBS-LRR (nucleotide-binding region; leucine-rich repeat) type genes which are often implicated in plant disease recognition/response (several genes have been identified to date in barley). The two genes (HORVU6HrG010720 and HORVU6HrG010730) are located adjacent to each other in the assembly. In addition, marker RhNZ6SNP7 is located within HORVU6HrG010730. Both genes may be considered “candidates” for the three scald resistances.
Over the course of this project we were able todevelop high-throughput TaqMan molecular marker assays linked to five different scald resistance genes located at three different locations within the barley genome. These markers will make selection and incorporation of scald resistance into future varieties more efficient and cost-effective for barley breeders. As evidence to this, we were able to register CDC Copper (TR14150), a two-row malting barley line which shows very good yield potential, strong straw and very good malt quality. This line also carries excellent scald resistance, derived from the 145L2 scald resistance source, which was selected using one of the TaqMan assays developed. This is the first malting variety released in Canada with excellent scald resistance. We hope that this line will provide better returns to growers who are involved with malting barley production in Alberta and western Saskatchewan where scald is more of an issue.
Updated July 6, 2018