Fig 2. Positional cloning of the resistance gene Co-1^HY.

(A) The primary genetic linkage map of Co-2322 gene constructed by Chen et al. [26]. (B) The fine mapping of the Co-2322 (or Co-1^HY) gene and associated molecular markers. Recombination distances are indicated on the left side of the linkage group in centiMorgans (cM), and the marker names are shown on the right side. (C) The physical map showing the locations of the Co-1^HY locus and SSR markers. The Co-1^HY region was positioned between 50,264,608 bp and 50,339,673 bp in an approximately 75 kb interval of chromosome 1 between the SSR markers PSSR0869 and PSSR0771. The dotted lines indicate common markers. (D) The predicted genes flank the target 75-kb region. Fifteen ORFs are shown as open arrows, and the parentheses show PCR markers Plc1, TF1, STK1 and Clp-N1 that were developed with reference to the predicted genes. (E) The amplification of the F₂ population with the PCR markers Plc1, TF1, STK1 and Clp-N1. P1: resistant parent; P2: susceptible parent; 1–10: susceptible individuals of the F₂ population; individual 10 in the markers of Plc1 and TF1 and individuals 5 and 6 in Clp-N1 are recombined. (F) Diagrammatic representation of the Co-1^HY mapping. The distribution of recombination events that were detected by high-resolution mapping is depicted. The hatched bar represents the region of the Hongyundou genome, and the open bar represents the region of the Jingdou genome. The number below the markers PSSR0869, Plc1, TF1, STK1, Clp-N1 and PSSR0771 represents the recombinant. Genotyping of the homozygous progeny delimited the Co-1^HY locus to an approximately 46 kb stretch flanked by Clp-N1 and TF1. P1: resistant parent; P2: susceptible parent; 1–10: susceptible individuals of the F₂ population; R1, R2: resistant individuals of the F₂ population. (G) Annotation of the 46-kb candidate region. The pentagons represent the predicted genes with the sizes indicated in the lengths of each gene, and the arrows indicate the relative orientation.