Location: Cereal Crops Improvement Research
Project Number: 3060-21000-046-034-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jul 1, 2024
End Date: Jun 30, 2025
Objective:
1) Develop segregating populations for genetic mapping of barley susceptibility genes Sps1 and Sptm1 to stripe rust and spot form net blotch, respectively; 2) finely locate Sps1.a and Sptm1 in barley; 3) clone the Sps1.a and Sptm1 genes using; 4) clone the Sps1.a and Sptm1 genes.
Approach:
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. Hereafter, this gene was named Sps1 give the functional allele controls disease specificity. To finely localize the Sps1 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 Sps1 gene with at least 1000 F2s. Otherwise, at least 300 F6 RILs will be used for genetic mapping. The candidate of Sps1 will be transferred to resistant BBA2890 for validation of its identity.
Caused by the necrotrophic fungal pathogen Pyrenophora teres f. maculata (Ptm), spot form net blotch (SFNB) is a foliar disease of barley that results in significant yield losses worldwide. A few major QTL have been consistently detected by multiple studies using various pathotypes, including an unknown locus on 7H (named Susceptibility to Ptm 1, or Sptm1 hereafter). To map and clone Sptm1, segregating populations will be derived from the cross between barley genotype Tradition (susceptible) and PI 67381 (resistant). At least three independent transgenic lines will be used for phenotype evaluation at both T0 and T1 generations. In the meantime, we will use the clustered CRISPR vector JD633 to knockout the Sptm1 gene in Tradition, and the resulting mutations in M0 plants will be detected by DNA sequencing.
