CYTOGENETIC, ENZYMATIC, AND RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM VARIATION OF MELOIDOGYNE SPP FROM SPAIN

A survey of the cytogenetic, enzymatic, and DNA variation of root-knot nematodes, Meloidogyne spp., involved a total of 19 populations from various hosts in several regions of Spain. Of these, nine populations were identified as M. arenaria, six as M. incognita, three as M. javanica, and one as M. hapla. All M. javanica populations were hypotriploids with 43-46 chromosomes. The M. arenaria populations were hypotriploids with 40-48 chromosomes, except one diploid population with 34. The M. hapla population was a hypotriploid with 43-45 chromosomes. To assess isozyme variation, we assayed 11 enzyme systems. Only three systems showed some variation. Esterase patterns allowed separation of the four Meloidogyne species and two different forms in M. incognita and M. arenaria. Malate dehydrogenase patterns separated M. hapla from the rest of the species. Glutamate oxaloacetate transaminase separated M. incognita from the other species. Variation at the nucleic acid level was examined with a 1.8-kb mitochondrial DNA probe, IB2-37, which allowed the differentiation of M. incognita, M. arenaria, and M. javanica, after digestion of nucleic acids with either EcoRI or HinfI. Oligonucleotide primers based on IB2-37 were used in polymerase chain reactions. DNA, amplified from 1-10 juveniles, was digested with HinfI and produced patterns identical to those obtained in hybridization experiments. This procedure also allowed separation of M. hispanica and M. microcephala from the four major species. These results demonstrate that enzyme phenotyping and nucleic acid analysis provide consistent species identification in Meloidogyne.