Mapping of a novel locus Ra conferring extreme resistance against potato virus A in cultivated potato (Solanum tuberosum L.)

Wei Huang, Jie Zheng, Bihua Nie, Jiana Li, Ruhao Chen, Xianzhou Nie, Zhen Tu, Kyle Gardner, Jiaru Chen, Manhua Yang, Jingcai Li, Jianke Dong, Hui Ma & Botao Song

Theoretical and Applied Genetics; August 2024; vol.137; article 198

Figure: Potato virus A symptom.

Key message

The Ra extreme resistance against potato virus A was mapped to the upper of chromosome 4 in tetraploid potato.

Abstract

Potato virus A (PVA) is one of the major viruses affecting potato worldwide and can cause serious disease symptoms and yield losses. Previously, we determined that potato cultivar Barbara harbors Ry_sto (genotype: Ryryryry) and Ra (genotype: Rararara) that each independently confer extreme resistance to PVA. In this study, employing a combination of next-generation sequencing and bulked-segregant analysis, we further located this novel Ra on chromosome 4 using a tetraploid BC₁ potato population derived from a Ry-free progeny (Rararararyryryry) of Barbara (RarararaRyryryry) × F58050 (rararararyryryry). Using 29 insertion–deletion (InDel) markers spanning chromosome 4, Ra was delimited by the InDel markers M8-83 and M10-8 within a genetic interval of 1.46 cM, corresponding to a 1.86-Mb genomic region in the potato DM reference genome. The InDel marker M10-8, which is closely linked with the resistance against PVA in the Ry-free segregating populations, was then used to screen 43 selected Ry_sto-free tetraploid potato breeding clones. The phenotype to PVA was significantly correlated with the present/absent of the marker, albeit with a 9.3% false positive rate and a 14.0% false negative rate. These findings are of importance in furthering the cloning of Ra and employing the marker-assisted selection for PVA resistance.

See https://link.springer.com/article/10.1007/s00122-024-04705-x