First report of, and additional information on, Meloidogyne konaensis (Nematoda: Meloidogyninae) parasitising various crops in Brazil

Abstract

In a survey for Meloidogyne spp. in different crops from 11 regions in Ceará State, Brazil, using esterase isozyme electrophoresis as a specific identification method, four atypical populations were characterised from cabbage, papaya, noni and canapum plants, all of which showed an esterase profile different from those previously detected in Brazil. Morphological studies showed typical characteristics of Meloidogyne konaensis. Perineal patterns of females were variable, similar to M. arenaria and M. incognita, stylet length 14-20 μm. In females, the knobs gradually merged with the shaft and the dorsal pharyngeal gland orifice (DGO) ranged from 4 to 7 μm. Although males are not frequently found, the stylet morphology provides the most useful source of diagnostic character for the species, having 6-12 large projections protruding from the shaft. The esterase pattern K3 is unique and species-specific with three major bands Rm 1.0, 1.17, 1.27 and a secondary band Rm 1.10. Some confusion about the true identity of this species was clarified in this study, including differentiation from M. paranaensis. A species-specific SCAR marker developed for M. paranaensis was tested and no amplification products were observed. In Neighbour-Joining analyses of ITS and D2-D3 rRNA sequences, M. konaensis from Brazil appeared clearly separated from M. paranaensis. Pathological tests indicated that coffee is not a host of M. konaensis as previously reported in the original description of this species.