Molecular Characterization of Root-Knot Nematodes on Selected Vegetables Grown in Kano State, Nigeria

Abstract

Root-Knot Nematode species are morphologically very similar to each other and identification to the species level is difficult. More than one root knot nematode species is sometimes found together in the same plant root. Therefore, fast and accurate identification is needed for management and breeding. Meloidogyne incognita is the predominant root-knot nematode species infecting tomato, okra, and capsicum in the surveyed vegetable fields of Kano State. An extensive field survey was carried out from June to September 2025 across four vegetable fields located within Kano State (Bichi, Bagwai, Dawakin/Tofa, and Ungogo). Tomato, okra, and capsicum plants were inspected for above-ground symptoms of nematode infestation. The results revealed that Ungogo LGA was the only location among the surveyed areas with severe and widespread infestation of root-knot nematodes, characterized by profuse galling, chlorosis, wilting, and general plant decline. Infected roots and rhizosphere soil samples were collected from heavily infested fields in the Center for Dryland Agriculture (CDA, BUK New Campus), located in Ungogo LGA. Nematodes were extracted from soil and Morphological identification was performed using Perennial pattern analysis under compound microscopy, indicating Meloidogyne incognita. Molecular analysis further validated this identification; the genomic DNA was extracted from single adult female nematodes using worm lysis buffer, followed by PCR amplification with species-specific SCAR primers SEC1F/SEC2R. The amplified products were separated on 1.5% agarose gel electrophoresis for species confirmation, which produced a distinct amplicon of approximately 502 bp, a diagnostic fragment widely reported for M. incognita in species-specific identification studies.