ARS | Publication request: Virulence of Meloidogyne incognita to expression of N gene in pepper

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 26, 2012
Publication Date: April 6, 2012
Citation: Thies, J.A. 2012. Virulence of Meloidogyne incognita to expression of N gene in pepper. Journal of Nematology. 43(2):90-94.

Interpretive Summary: The southern root-knot nematode, Meloidogyne incognita, causes major losses in pepper production in the US and world-wide. Resistant bell and hot pepper varieties have been developed and are known to perform well when planted in fields highly infested with root-knot nematodes. In this report, we describe studies in which several root-knot nematode resistant pepper varieties were tested in the greenhouse against a new strain of southern root-knot nematode that was found to be virulent on peppers in preliminary tests. All resistant pepper varieties (including bell types, cayenne types, and Scotch Bonnet-types) tested against this nematode strain were found susceptible. It will be important to continue evaluating resistant pepper varieties against different populations of southern root-knot nematode to determine whether the resistance is stable against other new nematode strains.

Technical Abstract: Five root-knot nematode resistant pepper genotypes and three susceptible pepper genotypes were compared for their reactions against a population of Meloidogyne incognita (Chitwood) Kofoid and White which had been shown to be pathogenic to bell pepper (Capsicum annuum) in preliminary tests. The pepper genotypes used in all experiments were the Capsicum annuum cultivars: Charleston Belle (resistant to M. incognita = R) , Keystone Resistant Giant (susceptible = S), Carolina Wonder (R), Yolo Wonder B (S), California Wonder (S), Carolina Cayenne (R), and the C. chinense cultigens: PA-426 (R), and PA-350 (S) . Root gall indices were > 3.0 for all genotypes in both tests except for PA-426 (GI=2.57) in test 1 and ‘Carolina Cayenne’ (2.83) in test 2. Numbers of eggs per gram fresh root (range: 20,635 to 141,319) and reproductive indices (range: 1.20 to 27.2) were high for all genotypes in both tests, indicating that all 8 genotypes tested were susceptible to M. incognita. The M. incognita population used in these studies overcame resistance conferred by the N gene in resistant genotypes of both C. annuum and C. chinense.