Taxonomy of coffee-parasitic root-knot nematodes, meloidogyne spp.

Abstract

Meloidogyne species are characterized primarily on morphological features of females, males and second-stage juveniles. Based on these characters, identifying the 17 coffee-parasitic Meloidogyne species is a difficult task even for well-qualified taxonomists. This chapter outlines the most diagnostic morphological and morphometric features for Meloidogyne taxonomy, and presents the useful characters for identification of those 17 species. In recent years, esterase phenotyping has become a practical and reliable taxonomic tool for this genus. Unfortunately, only 12 out of the 17 coffee-parasitic species have had their phenotypes characterized; M. africana, M. decalineata, M. kikuiensis, M. megadora and M. oteifae can only be identified by morphological features. Recently, a new identification tool has been developed: the multiplex PCR (SCAR primers) allows unambiguous differentiation of M. exigua, M. incognita and M. paranaensis from Brazil, with prospects for extending this method to other species. This chapter concludes by outlining studies and initiatives that should be undertaken to facilitate and improve the reliability of coffee-related Meloidogyne taxonomy.