Submitted to: American Journal of Potato Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/3/2005
Publication Date: 1/2/2006
Citation: Brown, C.R., Mojtahedi, H., James, S., Novy, R.G., Love, S. 2006. Development and evaluation of potato germplasm resistant to columbia root-knot nematode (meloidogyne chitwoodi). American Journal of Potato Research. 83:1-8. Interpretive Summary: Potato growers have an expensive proposition on hand. Besides paying for the cost of fertilizer, fuel to power equipment, electricity to pump irrigation water, in the Columbia Basin of the Pacific Northwest there is a huge cost associated with controlling the damage caused by little worms in the soil. The worm is the Columbia root-knot nematode. The cost of controlling this nematode is about 15% of the total cost of growing the potato. The nematode reproduces on the root system of the potato plant, produces numerous eggs, and the hatchlings invade the tubers and cause deformation of the tuber and blemishing of the flesh, revealed upon peeling. It is neither acceptable to the grocery store consumer or the processing industry. The control measure currently employed involves fumigation of the soil with strong chemicals. However, breeding research is offering an alternative. By incorporating resistance to the Columbia root-knot nematode obtained from wild Mexican potatoes, we have developed commercially acceptable potato lines that do not allow the nematode to reproduce on the root system of the potato plant. Without reproduction there are no newly hatched nematode juveniles available to spoil the tubers. Introduction of this new genetic material into commercial utilization will reduce the cost of production significantly and contribute substantial relief to the environment by reducing the use of the fumigants that control the problem at present.
Technical Abstract: Columbia root-knot nematode (Meloidogyne chitwoodi) (CRN) is a serious pest of potato in the Pacific Northwest of the US. Small initial populations are capable of causing crop loss due to the ability of this nematode to reproduce rapidly in the long growing season of the Columbia Basin of Washington or Oregon. Presently, fumigation of the soil is the only option to reduce the nematode damage. Developing resistance to CRN is highly desirable to reduce the control cost and alleviate environmental concerns due to use of fumigants. Resistance to CRN was found in two wild Solanum spp. Resistance from S. bulbocastanum was introduced via protoplast fusion and S. hougasii via sexual hybridization. Subsequent breeding consisted of repeated backcrossing and selection. The dominant monogenic inheritance was expressed in undiminished fashion across several backcross generations. Selected resistant clones from the BC4 and BC5 of the S. bulbocastanum introgression populations had total marketable yields and yields over 4 ounces as good as or better than commercial standards tested in replicated yield trials in three locations. Percent of tubers weighing over 4 ounces was not significantly different from commercial standards. The resistance phenotype, failure of the nematode to reproduce on the root systems, was sufficiently effective to prevent economic damage in field exposures. All M. chitwoodi resistant clones are pollen sterile. Germplasm listed is available upon request.