Analysis of a satellite DNA from Meloidogyne hapla and its use as a diagnostic probe

A Styl satellite DNA previously isolated from Meloidogyne hapla gave hybridization signals only with the five M. hapla populations tested in Southern blot experiments, indicating that this satellite sequence is species-specific. Because of its high level of reiteration and its variability, this sequence was able to discriminate both between Meloidogyne species and among three M. hapla populations. The StyI satellite DNA was polymorphic at the intraspecific level, since hybridization patterns of M. hapla populations exhibited very different profiles with polymorphisms characterizing each of the three populations tested. In simple squashed-nematode experiments, we were able to unambiguously identify M. hapla vs. M. chitwoodi, which are sympatric. The procedure was effective even on a single female located in root tissues, with the main advantage that it avoided time-consuming DNA extraction procedures. Therefore, in a case where confusion may occur among some particularly damaging nematodes, this very sensitive technique may prove to be reliable. Such satellite DNA sequences should provide rapid, inexpensive, and user-friendly field tools for Meloidogyne species identification