Location: Cereal Crops Research
Project Number: 3060-21000-038-29-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jul 1, 2020
End Date: Jun 30, 2021
1) Functionally validate the barley Fhb1 ortholog in susceptibility to Fusarium head blight (FHB); 2) Finely locate and clone the recessive gene rps1.a for barley resistance to stripe rust; 3) Identify the resistance loci against hessian fly and develop biparental populations for genetic mapping.
FHB1, a QTL in the Chinese wheat variety Sumai3, confers durable and broad-spectrum resistance to Fusarium species, and it has been extensively used as the best source of FHB resistance in wheat. The recent breakthrough on FHB research is that the FHB1 gene has been successfully cloned and functionally characterized in wheat. It was revealed that the FHB1, encoding a putative histidine-rich calcium-binding protein (TaHRC), is probably required for disease susceptibility. Isolation of this major QTL provides novel perspective to control this devastating disease, and FHB immunity may be achieved by manipulation of the FHB1 orthologs in other species. Therefore, knocking out of the barley ortholog of FHB1 may disrupt FHB susceptibility for this species. BLAST searches showed that the barley ortholog HvHRC is a single copy gene and resides within the genomic region syntenic to the wheat FHB1 locus. To characterize the Fhb1 ortholog and determine if this gene is also required for FHB susceptibility in barley, we will use the CRISPR technology to knock out the HvHRC gene in barley cv Conlon. Disease levels in the derived knockout mutants will be investigated. Barley stripe rust is caused by the biotrophic fungal pathogen to Puccinia striiformis f. sp. hordei. Resistance to stripe rust conferred by a single gene usually is race-specific and easily defeated by emergence of new virulent races. A recessive resistance controlled by rps1.a in barley cv BBA2890 is effective to most of the races identified in the US. Assisted with resistance gene analog polymorphism (RGAP) and SSR markers, RPS1.a was mapped onto 3H. To finely localize the RPS1.a gene, we will make an advanced segregating population using BBA2890 (R) and Steptoe (S). However, 94 F2s with extreme resistance or susceptibility will be first genotyped with barley 50k iSelect SNP array to identified linked SNPs. If the disease phenotype can be distinguished at the F2 generation, CAPS, dCAPS or STARP markers will be designed to saturate and map the RPS1.a gene with at least 1000 F2s. Otherwise, at least 300 F6 RILs will be used for genetic mapping. The candidate of RPS1.a will be transferred to resistant BBA2890 for validation of its identity. The Hessian fly became an important pest of barley in the US. Economic loss can be caused by Hessian fly through plant death, stunted seeding or tillers, stem breakage, and reduced seed size or number. Employment of host resistance is the most effective and environment-sustainable strategy for Hessian fly control. However, genetic resistance in barley to Hessian fly remains largely unknown. We will evaluate a panel of 186 barley accessions, which were already genotyped with 9K iSelect SNP array. A genome-wide association study will be conducted for discovery of Hessian fly resistance loci. Biparental populations, such as F2, RILs and NILs, will be used to confirm and genetically map these identified genes. User-friendly markers, such as STARP markers, will be designed to assist breeding selection for Hessian fly resistance.