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Title: THE EFFECT OF THE MI GENE IN TOMATO ON REPRODUCTIVE FACTORS OF MELOIDOGYNE CHITWOODI AND M. HAPLA

Author
item Brown, Charles
item MOJTAHEDI, HASSAN - WSU-PROSSER
item SANTO, GERALD - WSU-PROSSER
item WILLIAMSON, V - UNIV CALIF-DAVIS

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Columbia root-knot nematode, a microscopic worm-like organism that lives in the soil, is a serious pest of potato in the Northwest. When nematodes hatch they invade potatoes that the plant is producing under the surface of the soil, causing blemishes that look like bumps on the outside and dark spots in the flesh when the potato is peeled. Twenty million dollars is spent every year in the Columbia Basin on chemical fumigants to prevent forty million dollars of damage from occurring. This study shows that a gene in tomato is effective against this nematode. It is important because the gene in tomato can be transferred to potato by traditional breeding or by transformation, a method of inserting genes through genetic engineering, in the future when the tomato gene is cloned. These results suggest that movement of genes across crop species may be an effective remedy for certain problems and in fact may be the most efficient way to solve the problem caused by this pest, especially if the gene is available for transformation. More studies are needed in the future to examine the probable effectiveness of the tomato gene against different races and isolates of the nematode. Genetic resistance in new potato varieties is the best way of reducing the use of pesticides and increasing profitability of potato production through reduction in losses and by lessening the cost of production.

Technical Abstract: The effect of the Mi gene on the reproductive factor of Meloidogyne chitwoodi and M. hapla, major nematode pests of potato, was measured using nearly isogenic tomato lines differing in presence or absence of the Mi gene. The Mi allele controlled resistance to reproduction of race 1 of M. chitwoodi. In contrast, the Mi allele controlled resistance to one isolate eof race 2 but not the other. No resistance to race 3 of M. chitwoodi or t M. hapla was found. Variability in response to isolates of race 2 may reflect diversity of virulence genotypes heretofore undetected. Tomato genotypes with resistance to other Meloidogyne species were not used as differentials to define race categories within M. chitwoodi. Resistance to race 1 of M. chitwoodi could be useful in potato if the Mi gene were functional following transferal by gene insertion technology into potato. Since the Mi is not superior to RMc1 derived from Solanum bulbocastanum, the transferal by protoplast fusion appears to offer no advantage.