Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2003
Publication Date: 11/14/2003
Citation: BROWN, C.R., MOJTAHEDI, H., SANTO, G.S. CHARACTERISTICS OF RESISTANCE TO COLUMBIA ROOT-KNOT NEMATODE INTROGRESSED FROM SEVERAL MEXICAN AND NORTH AMERICAN WILD POTATO SPECIES. ACTA HORTICULTURAE, 619:117-125. 2003. Interpretive Summary: Potato growers are under constant pressure to decrease costs of production. Soil fumigation to control Columbia root-knot nematode is among the higher costs of production. This microscopic worm reproduces on the root system and newly hatched juveniles penetrate the tuber causing dark spots and a bumpy surface on the potato's surface. Fumigating to control this pest can cost up to $350 per acre. A good alternative would be to breed resistant varieties. Resistance to Columbia root-knot nematode is not easy to find. In fact, we had to use wild potatoes from Mexico as our source of resistance. Although this is a tremendous amount of work and takes many years to accomplish we have now been able to use new molecular tools that allow us to track genes from wild potatoes and shave off years from the process of breeding. We have found three wild species to date that have resistance. One species has been utilized in particular and this has given us advanced potato lines with good yield and processing characteristics, and resistance to the nematode. Breeding will continue through more cycles of crossing and selection. A successful variety will cut the cost of production by permitting a decrease in the use of soil fumigants which could contribute to a reduction in pesticide contamination of groundwater.
Technical Abstract: Columbia root-knot nematode is a serious pest of potato in the Pacific Northwest of the US and in the Netherlands. At present, control is achieved by chemical fumigation, a costly practice. Resistance has been found in several wild species endemic to Mexico and the United States. This type of resistance is expressed as lower root infestation rates and a barrier to the successful establishment of a feeding site, giant cell, and reproduction. In resistant roots, the juveniles remain in a vermiform stage. It appears that localized cell death accompanies the resistance reaction, suggesting the functioning of an R-gene. The inheritance and chromosomal location was identified for two sources of resistance, Solanum bulbocastanum, a diploid, and S. hougasii, a hexaploid, as the upper arm of chromosome 11. The localization of resistance to the same chromosome suggests synteny and the possible presence of the primitive B genome of S. bulbocastanum in S. hougasii. Recent surveys have confirmed that two out of twelve plant introduction accessions of S. fendleri tested were 100% resistant to race 1 of Columbia root-knot nematode. Resistance derived from Solanum bulbocastanum was introduced into cultivated potato by protoplast fusion, and a traditional backcrossing program has produced advanced breeding clones with root-knot resistance, good horticultural type, acceptable fry color and long tuber.