Diversity of Root-knot Nematodes Associated with Tubers of Yam (Dioscorea spp.) Established Using Isozyme Analysis and Mitochondrial DNA-based Identification.

Yao A. Kolombia, Gerrit Karssen, Nicole Viaene, P. Lava Kumar, Nancy de Sutter, Lisa Joos, Danny L. Coyne, Wim Bert

Abstract


The root-knot nematodes (RKN), Meloidogyne spp., represent an important threat to yam (Dioscorea spp.) production in West Africa. With the aim to establish the diversity of RKN species affecting yam tubers, for control and resistance screening purposes, surveys were conducted in the main yam producing areas of Nigeria. Galled tubers (N = 48) were collected from farmers’ stores and markets in nine states in Nigeria and in one district in Ghana. RKN isolated from yam tubers were identified using enzyme phenotyping (esterase and malate dehydrogenase) and mitochondrial DNA (mtDNA) NADH dehydrogenase subunit 5 (Nad5) barcoding. Examination of 48 populations revealed that yamtubers were infested byMeloidogyne incognita (69%), followed byM. javanica (13%), M. enterolobii (2%), and M. arenaria (2%). Most of the tubers sampled (86%) were infected by a single species, and multiple species of RKN were detected in 14%of the samples. Results of both identificationmethods revealed the same species, confirming their accuracy for the identification of these tropical RKN species. In addition to M. incognita, M. javanica, and M. enterolobii, we report for the first time M. arenaria infecting yam tubers in Nigeria. This finding extends the list of yam pests and calls for caution when developing practices for yam pest management.

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