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United States Department of Agriculture

Agricultural Research Service

Title: Expression of Nematode Resistance in Plant Introductions of Arachis Hypogaea.

Authors
item Timper, Patricia
item Holbrook, C
item Xue, H - NORTH CAROLINA STATE UNIV

Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 13, 2000
Publication Date: December 1, 2000
Citation: Timper, P., Holbrook, Jr., C.C., Xue, H.Q. 2000. Expression of nematode resistance in plant introductions of Arachis hypogaea. Peanut Science. 27:78-82.

Interpretive Summary: The peanut root-knot nematode is a world-wide pest of peanut. Several moderately resistant plant types have been identified in the cultivated peanut species. Our objective was to determine how the resistant peanuts affect the life cycle of the nematode. We examined four potential affects on the nematode: 1) reduced penetration of roots, 2) fewer nematodes establish functional feeding sites within roots, 3) slower maturation, and 4) reduced reproduction (eggs per female). Peanut seedlings were inoculated with juveniles of the peanut root-knot nematode, and transplanted 3 d later to synchronize nematode development. The resistant peanuts were compared to the cultivar Florunner, a susceptible control. The number of juveniles within the roots was similar in resistant and susceptible peanut after 3 days; however, numbers were lower in two of the resistant peanuts than in Florunner after 10 d. A greater percentage of juveniles failed to develop in all of the resistant peanuts (72 to 79%) than in Florunner (50%) after 17 days. Of the juveniles that did begin to develop, the rate of maturation and reproduction was similar in resistant and susceptible peanuts. A lack of development indicates that the juveniles failed to establish a feeding site. Therefore, the primary affect of the resistant peanuts appears to be a reduction in the percentage of juveniles that establish a functional feeding site.

Technical Abstract: The peanut root-knot nematode (Meloidogyne arenaria, race 1) is a world- wide pest of peanut (Arachis hypogaea). Several moderately resistant genotypes have been identified in the cultivated peanut species. Our objective was to determine the expression of resistance for six of these genotypes. We examined four potential expressions of resistance: 1) reduced penetration, 2) fewer second-stage juveniles (J2) establish functional feeding sites, 3) slower maturation, and 4) reduced fecundity (eggs per female). Peanut seedlings were inoculated with J2 of M. arenaria, and transplanted 3 d later to synchronize nematode development. The resistant genotypes were compared to the cultivar Florunner, a susceptible control. Penetration was assessed at 3 and 10 d; development at 10 (or 12), 17, 22, and 27 d; and fucundity at 60 d after inoculation. The experiments were conducted in a greenhouse or growth chamber. The number of juveniles within the roots was similar in resistant and susceptible peanut after 3 d; however, numbers were lower in two of the resistant genotypes than in Florunner after 10 d. A greater percentage of J2 failed to develop in all of the resistant genotypes (72 to 79%) than in Florunner (50%) after 17 d. Of the J2 that did begin to develop, the rate of maturation and fecundity was similar in resistant and susceptible genotypes. A lack of development indicates that the J2 failed to establish a feeding site. Therefore, the primary expression of resistance in the six peanut genotypes appears to be a reduction in the percentage of J2 that establish a functional feeding site. The decline in J2 after infection may be related to the failure to establish a feeding site.

Last Modified: 7/27/2014
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