Comparison between enzymatic and molecular diagnostic techniques for identification of Meloidogyne spp. on coffee in Brazil and restricted occurrence of M. izalcoensis

Abstract

Root-knot nematodes (RKNs), Meloidogyne spp. are considered important pathogens of the coffee crop, limiting production and causing economic losses. Meloidogyne izalcoensis was recently detected in the Triângulo Mineiro region, Minas Gerais (MG) state of Brazil, parasitizing coffee plants. To investigate the distribution of this particular nematode species in this region, two small prospective surveys targeting Meloidogyne spp. on coffee plantations were carried out, employing two different techniques (esterase phenotypes (Est) and SCAR markers) in the municipalities of Araguari and Indianópolis where M. izalcoensis had been previously detected. Unfortunately, the high level of female degeneration in the second survey prevented us from identifying the species using esterase phenotypes. In both surveys, we employed the SCAR-coffee Kit, which proved to be highly effective in accurately identifying all the species of Meloidogyne found in coffee plants especially M. exigua. By using eggs and second stage juveniles (J2s) extracted from coffee roots, we obtained reliable markers for the identification of M. exigua (41.67%), M. incognita (33.33%), M. paranaensis (20.83%) and M. izalcoensis (4.17%), which can be used as unique tools in multiplex in the characterization of Meloidogyne spp. from coffee. Mixed population species were also observed in 20.83% of the samples. The use of SCAR markers proved to be the most effective tool for accurately identifying M. exigua and mixed species. These surveys confirmed that M. izalcoensis has a restricted occurrence in the region where it was initially detected.