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.