Genetic diversity of the root‐knot nematode <i> <scp>M</scp> eloidogyne ethiopica </i> and development of a species‐specific <scp>SCAR</scp> marker for its diagnosis

Abstract

Meloidogyne ethiopica is an important nematode pathogen causing serious economic damage to grapevine in C hile. In B razil, M . ethiopica has been detected with low frequency in kiwifruit and other crops. The objectives of this study were to evaluate the intraspecific genetic variability of M . ethiopica isolates from B razil and C hile using AFLP and RAPD markers and to develop a species‐specific SCAR ‐ PCR assay for its diagnosis. Fourteen isolates were obtained from different geographic regions or host plants. Three isolates of an undescribed M eloidogyne species and one isolate of M . ethiopica from K enya were included in the analysis. The results showed a low level of diversity among the M . ethiopica isolates, regardless of their geographical distribution or host plant origin. The three isolates of M eloidogyne sp. showed a high homogeneity and clustered separately from M . ethiopica (100% bootstrap). RAPD screenings of M . ethiopica allowed the identification of a differential DNA fragment that was converted into a SCAR marker. Using genomic DNA from pooled nematodes as a template, PCR amplification with primers designed from this species‐specific SCAR produced a fragment of 350 bp in all 14 isolates of M . ethiopica tested, in contrast with other species tested. This primer pair also allowed successful amplification of DNA from single nematodes, either juveniles or females and when used in multiplex PCR reactions containing mixtures of other root‐knot nematode species, thus showing the sensitivity of the assay. Therefore, the method developed here has potential for application in routine diagnostic procedures.