Biometrical, biological, biochemical and molecular characteristics of Meloidogyne incognita isolates and related species Marcilene Fernandes Almeida dos Santos & Cleber Furlanetto & Maria Rita Alves Almeida & Marina Dechechi Gomes Carneiro & Fabiane Castro Mota & Ana Cristina Meneses Mendes Gomes & Natália Orrú Reis Silveira & Joelma Gardênia Pereira Silva & Philippe Castagnone-Sereno & Myrian Silvana Tigano & Regina Maria Dechechi Gomes Carneiro Accepted: 31 May 2012 / Published online: 25 September 2012 # KNPV 2012 Abstract Meloidogyne incognita is one of the most polyphagous species of root-knot nematodes occurring in Brazil and worldwide. Eight M. incognita isolates were studied, representing two enzymatic phenotypes (esterase and malate desydrogenase: I1/N1, I2/N1) and four cryptic Meloidogyne sp.1 (S2/N1) isolates, repre- senting one cytological type (3n 0 40–46). Three M. hispanica isolates (Hi3/N1, 2n 0 32–36) and two of an atypical Meloidogyne sp.2 (S2a/N3, 3n 0 40–44) were included in this study for comparison. All isolates were tested with three M. incognita-specific molecular markers . The primer pairs B06F/R, miF/R and incK14F/R amplified three species-specific fragments of 1,200 bp, 955 bp and 399 bp, respectively for M. incognita and Meloidogyne sp.1 isolates. No amplifica- tion occurred in the M. hispanica and Meloidogyne sp.2 isolates, except with primers miF/R (1,650 bp). The genetic variability of the Meloidogyne spp. isolates was evaluated, using RAPD and ISSR markers. The phylogenetic analyses revealed two strongly supported monophyletic clades: clade I, consisting of M. hispanica and the atypical Meloidogyne sp.2 isolates, and clade II, clustering together all M. incognita and the Meloidogyne sp.1 isolates. Considering the biometrical, cytological and molecular approaches, it was possible to conclude that the isolates with three enzymatic pheno- types (I1/N1, I2/N1 and S2/N1) presented the character- istics described for M. incognita. Some correlations were detected between the isozymatic phenotypes and the tree topology (S2a/N3, Hi3/N1, I1/N1, S2/N1), but no strict correlation could be observed for the phenotype I2/N1 and one isolate of S2/N1. Morphologically, the Msp.2 isolates differ from M. incognita and M. Eur J Plant Pathol (2012) 134:671–684 DOI 10.1007/s10658-012-0018-1 M. F. A. dos Santos : M. R. A. Almeida : M. D. G. Carneiro : F. C. Mota : A. C. M. M. Gomes : N. O. R. Silveira : J. G. P. Silva : M. S. Tigano : R. M. D. G. Carneiro (*) EMBRAPA-Recursos Genéticos e Biotecnologia, Brasília DF 70849-970, Brazil e-mail: recar@cenargen.embrapa.br M. F. A. dos Santos : C. Furlanetto : J. G. P. Silva Departamento de Fitopatologia, Universidade de Brasília, Brasília DF 70910-900, Brazil P. Castagnone-Sereno INRA-UMR1355, UNSA, CNRS UMR7354, Institut Sophia Agrobiotech, 400 route des Chappes, BP167, 06903 Sophia Antipolis, Frances