THE INCORPORATION OF RESISTANCE TO GLOBODERA-PALLIDA INTO SOLANUM-TUBEROSUM GERMPLASM ADAPTED TO NORTH-AMERICA

Potato seeds of 24 families consisting primarily of Solanum tuberosum ssp. andigena with some S. vernei germplasm that were segregating for resistance to potato cyst nematodes (Globodera pallida races P4A and P5A and G. rostochiensis race R1A) were obtained from the International Potato Center. These seeds produced 468 clones with sufficient tubers for evaluation for resistance to G. pallida races P4A and P5A in pot tests at the International Potato Center. Twenty-six of these clones, selected for a high degree of resistance to G. pallida races P4A and P5A, were crossed with neotuberosum x Solanum tuberosum hybrids that had been selected for resistance to G. rostochiensis race R1A (golden nematode) and the viruses PVX and PVY. The resultant progenies possessed a high degree of resistance to all three races of the potato cyst nematode. From these progenies, 23 clones were selected for resistance to the three races (G. pallida P4A and P5A, G. rostochiensis R1A) of potato cyst nematodes. The better adapted clones with resistance to the 3 races of potato cyst nematodes will be used in the next cycle of back-crossing.