Ulrike Gartner,  Miles R. Armstrong, Sanjeev K. Sharma,  John T. Jones,  Vivian C. Blok,  Ingo Hein &  Glenn J. Bryan

Theoretical and Applied Genetics; May 2024; Volume 137, article number 106

Wild potato

Key message

A new resistance locus acting against the potato cyst nematode Globodera pallida was mapped to chromosome VI in the diploid wild potato species Solanum spegazzinii CPC 7195.

Abstract

The potato cyst nematodes (PCN) Globodera pallida and Globodera rostochiensis are economically important potato pests in almost all regions where potato is grown. One important management strategy involves deployment through introgression breeding into modern cultivars of new sources of naturally occurring resistance from wild potato species. We describe a new source of resistance to G. pallida from wild potato germplasm. The diploid species Solanum spegazzinii Bitter accession CPC 7195 shows resistance to G. pallida pathotypes Pa1 and Pa2/3. A cross and first backcross of S. spegazzinii with Solanum tuberosum Group Phureja cultivar Mayan Gold were performed, and the level of resistance to G. pallida Pa2/3 was determined in progeny clones. Bulk-segregant analysis (BSA) using generic mapping enrichment sequencing (GenSeq) and genotyping-by-sequencing were performed to identify single-nucleotide polymorphisms (SNPs) that are genetically linked to the resistance, using S. tuberosum Group Phureja clone DM1-3 516 R44 as a reference genome. These SNPs were converted into allele-specific PCR assays, and the resistance was mapped to an interval of roughly 118 kb on chromosome VI. This newly identified resistance, which we call Gpa VI^l_spg, can be used in future efforts to produce modern cultivars with enhanced and broad-spectrum resistances to the major pests and pathogens of potato.

See https://link.springer.com/article/10.1007/s00122-024-04605-0#Abs1

Fig 4: Distribution of SNPs identified by GenSeq at 5% mismatch rate. Each set of coloured data represents a specific chromosome. Coloured “spikes” represent the number of single and low copy number genes targeted by probes across each chromosome. Each dot represents SNPs, and its placement on the y-axis determines the number of SNPs identified in a 1 Mb bin. Panel A shows the SNPs identified between the two parental lines. Panel B shows the SNPs found in the two bulks with the expected ratio of the alternative allele being 0.5 ± 0.1 for the resistant bulk and 0 or 1 ± 0.1 for the susceptible bulk. Panel C shows the informative SNPS identified and validated to be intragenic in the bulks and parents