Molecular Screening and Field Validation of Potato Germplasm for Resistance to Potato Cyst Nematodes

Potato cyst nematode (PCN; Globodera spp.) is an internationally quarantined pest threatening potato production in Yunnan, Sichuan, and Guizhou, China. We screened 418 potato accessions using markers 57R (H1), Gro1-4(Gro1-4), and Gpa2-2(Gpa2). Detection frequencies were 40.43% (Gpa2-2), 14.35% (57R), and 3.11% (Gro1-4); 50.48% carried at least one marker, 7.42% carried two markers, and none carried all three. Based on marker genotypes, nine representative accessions (five H1-carrying, two Gpa2-only, two marker-free) were field-tested in a nursery infested with Globodera rostochiensis. All five H1-carrying accessions showed no cyst formation (RF = 0), indicating high resistance. The Gpa2-only accessions had RF values of 0.37 and 0.58, indicating partial resistance, although Gpa2 mainly targets Globodera pallida. Marker-free accessions were susceptible (RF ≥ 0.79). According to international criteria (RF < 0.1 considered highly resistant), five accessions—‘Dianshu 1208’, ‘Dianshu 14023’, ‘Dianshu 1520’, ‘Diancaishu 102’, and ‘Atlantic’—were confirmed to be highly resistant. These results indicate that H1 is associated with effective resistance to G. rostochiensis in the tested accessions and highlight the value of combining marker-assisted selection with field validation for reliable PCN resistance identification.