Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/1996
Publication Date: N/A
Interpretive Summary: The southern root-knot nematode is a major pest of pepper in the United States. The primary control method at present is soil fumigation, but an alternative measure will be needed by the end of the decade because of the pending withdrawal of the leading fumigant (methyl bromide) from the U. S. market. A suitable alternative control measure would be the use of resistant cultivars. The results of a series of greenhouse experiments demonstrated that the resistance exhibited by the cayenne-type pepper 'Carolina Hot' is superior to the resistance exhibited by the pimiento-type pepper 'Mississippi Nemaheart.' Both cultivars were shown to possess the same dominant resistance gene. However, 'Carolina Hot' was found to possess a second, recessive-type, gene, and this extra gene accounted for the superior resistance exhibited by the cayenne cultivar. The ease and reliability of evaluating plants for resistance to root-knot nematodes and the availability of a simply inherited source of outstanding resistance makes breeding for southern root-knot nematode resistance a viable objective in pepper breeding programs. Resistant cultivars of bell-type peppers are badly needed by the fresh-market industry, and their availability would eliminate the need to use pesticides to control the southern root-knot nematode.
Technical Abstract: A series of greenhouse experiments were conducted to determine the inheritance of the high level of southern root-knot nematode resistance exhibited by the cayenne pepper 'Carolina Hot' and to compare the genetic nature of this resistance to that exhibited by 'Mississippi Nemaheart.' Evaluation of parental, F1, F2, and backcross generations of the cross 'Mississippi Nemaheart' x 'California Wonder' confirmed an earlier published report that the 'Mississippi Nemaheart' resistance is conditioned by a single dominant gene. Evaluation of parental, F1, F2, and backcross generations of a cross between highly resistant and highly susceptible lines selected from a heterogeneous 'Carolina Hot' population indicated that the resistance exhibited by 'Carolina Hot' is conditioned by two genes, one dominant and one recessive. Evaluation of the parental and F2 populations of a cross between 'Mississippi Nemaheart' and the highly resistant 'Carolina Hot' line indicated that the dominant resistance gene in 'Mississippi Nemaheart' is allelic to the dominant resistance gene in 'Carolina Hot.' The presence of the second resistance gene in 'Carolina Hot' probably accounted for its high level of resistance.