INTROGRESSION OF RESISTANCE TO COLUMBIA AND NORTHERN ROOT-KNOT NEMATODES FROM SOLANUM-BULBOCASTANUM INTO CULTIVATED POTATO

Resistance to Meliodogyne chitwoodi races 1 (MC1) and 2 (MC2) and M. hapla (MH) derived from Solanum bulbocastanum was introduced into the cultivated potato gene pool through somatic fusion. The initial F-1 hybrids showed resistance to the three nematodes. Resistance to reproduction on roots by MC1 was accompanied by resistance to tuber damage in F-1 clones. Tuber damage sometimes occurred, however, in hybrids of BC1 progeny resistant to reproduction on roots when MC2 and MH were the challenging nematodes. Resistance to reproduction was transferred into BC1 individuals, but a greater proportion of BC1 progeny was resistant to MC1 than to MC2 or MH. Resistance to MC1 appears to be dominant and discretely inherited. F-1 and BC1 progeny were pollen sterile, but seed were produced from crosses using cultivated tetraploid pollen sources. Approximately 11 and 33 per cent of pollinations produced berries on F-1 and BC1 pistillate parents, respectively. Seed yield increased fourfold overall in crosses with F-1 compared to BC1 individuals.