February 2018: The Three-Pistil (Pis1) QTL in Wheat

A map for the QTL containing the three-pistil gene (Pis1) recently published by Yang et al (2017) BMC Genomics 18:567, including 127 predicted protein-coding genes flanked by KASP markers has been added to GrainGenes. The Pis1 gene is expressed in the mutant line CM28TP originating from Chuanmai 28, directing the plant to produce three seeds where normal wheat produces one seed. The causative gene for this mutation has not been identified yet, but the QTL contains 10 loci that are candidate genes for this trait. This lays the groundwork for map-based cloning of the Pis1 Gene.

Abstract from BMG-18-567:
Background: The wheat mutant line three-pistil (TP) exhibits three pistils per floret. As TP normally has two or three seeds in each of the florets on the same spike, there is the possibility of increasing the number of grains per spike. Therefore, TP is a highly valuable mutant for breeding and for the study of floral development in wheat. To map the three-pistil gene (Pis1), genotyping-by-sequencing single-nucleotide polymorphism (GBS-SNP) data from an F2 mapping population (CM28 x CM28TP) was used to construct a genetic map that is of significant value. Results: In the present study, a high-density genetic map of wheat containing 2917 GBS-SNP markers was constructed. Twenty-one linkage groups were resolved, with a total length of 2371.40 cM. The individual chromosomes range from 2.64 cM to 454.55 cM with an average marker density of 0.81 cM. The Pis1 gene was mapped using this high-resolution map, and two flanking SNP markers tightly linked to the gene, M70 and M71, were identified. The Pis1 is 3.00 cM from M70 and 1.10 cM from M71. In bread wheat genome, M70 and M71 were found to delimit a physical distance of 3.40 Mb, which encompasses 127 protein-coding genes. To validate the GBS-generated genotypic data and to eliminate missing marker data in the Pis1 region, five Kompetitive Allele-Specific PCR (KASP) assays were designed from corresponding GBS sequences, which harbor SNPs that surround Pis1. Three KASP-SNP markers, KM70, KM71, and KM75, were remapped to the Pis1 gene region. Conclusions : This work not only lays the foundation for the map-based cloning of Pis1 but can also serve as a valuable tool for studying marker-trait association of important traits and marker-assisted breeding in wheat.

Visit the GrainGenes MapData page Wheat, CM28xCM28TP, Pis1 QTL

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