Morphological, Biometrical, Biochemical, and Molecular Characterization of the Coffee Root-Knot Nematode Meloidogyne...

Meloidogyne megadora infects coffee trees, an economically important crop worldwide. The accurate identification of M. megadora is essential for the development of preventive measures to avoid the dispersion of this pathogen and establishment of efficient and sustainable integrated pest management programs. One M. megadora isolate was studied by biometrical, biochemical, and molecular characteristics (random amplified polymorphic DNA [RAPD] and PCR of internal transcribed spacer [ITS] region). Biometrical characteristics of M. megadora females, males, and second-stage juveniles were similar to the original description. Biochemical studies revealed a unique enzyme pattern for M. megadora esterases (Me3) that allowed for species differentiation. Three RAPD primers (OPG-4, OPG-5, and OPG-6) produced specific bands to all Meloidogyne spp. studied: M. megadora, M. arenaria, M. incognita, and M. javanica. Molecular analysis of the ITS region resulted in an amplification product of 700 bp. The phylogenetic relationship between M. megadora and several Meloidogyne spp. sequences was analyzed, revealing that M. megadora clearly differs from the most common root-knot nematode species. Based on the studies conducted, isozyme analysis remains a useful and efficient methodology for M. megadora identification when females are available. Further studies will be needed to convert the M. megadora differential DNA fragment obtained by RAPD and develop a species-specific sequence-characterized amplified region PCR assay for its diagnosis based on second-stage juveniles.