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ABSTRACT The virulence of Meloidogyne hapla, M. chitwoodi, and M. fallax was studied on genotypes of Solanum spp. in a greenhouse. Juveniles of 11 M. hapla race A isolates, 3 M. hapla race B isolates, and 5 mono-female lines of a M. hapla race A isolate were inoculated on S. chacoense, S. hougasii, and S. sparsipilum. Juveniles of eight M. chitwoodi isolates, five M. fallax isolates, and six mono-female lines of a M. chitwoodi isolate were inoculated on S. bulbocastanum, S. chacoense, S. hougasii, S. stoloniferum, and S. tuberosum. Virulence was expressed as nematode reproduction 8 weeks after inoculation. Nematode reproduction was estimated by the number of egg masses and, in one experiment, by the number of hatched second-stage juveniles per inoculated juvenile. Considerable variation in virulence and resistance was observed among M. hapla isolates and plant genotypes, respectively. The M. hapla isolate-plant species interaction was highly significant. The response to M. chitwoodi ranged from susceptible (S. tuberosum and S. chacoense) to highly resistant (S. bulbocastanum and S. hougasii). S. tuberosum was susceptible to M. fallax, whereas all four wild species were resistant. In contrast to M. hapla, no significant isolate-plant genotype interaction was obtained for M. chitwoodi or M. fallax, indicating no or little intraspecific variation in virulence. M. chitwoodi juveniles in species mixtures with M. fallax isolates appeared to be able to break the resistance of S. bulbocastanum and S. hougasii. Significant differences among mono-female lines of M. hapla and M. chitwoodi were observed, indicating heterogeneity of pathogenicity within meiotic parthenogenic Meloidogyne populations. 相似文献
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Sylvie Gamel Emilie Huchet Anne-Claire Le Roux-Nio Géraldine Anthoine 《European journal of plant pathology / European Foundation for Plant Pathology》2014,138(4):807-817
Several conventional PCR tests have been developed for the identification of the European quarantine root-knot nematodes Meloidogyne chitwoodi and M. fallax but data are lacking for the evaluation of their performance in terms of sensitivity, repeatability, reproducibility and specificity against a large range of populations. This study evaluated the performance criteria of three conventional PCR tests recommended by the consensus diagnostic protocol for Meloidogyne chitwoodi and Meloidogyne fallax published by the European and Mediterranean Plant Protection Organization (EPPO): a species-specific PCR (IGS target), a SCAR PCR, and a rDNA ITS PCR-RFLP. Evaluation was carried out with DNA extracts from juveniles, males and females according to EPPO recommendations for test validation. A minimum of 34 populations of target and non target nematode species were tested to check the specificity of these three PCR assays. The three PCR tests were ranked according to their specificity (with regard to cross reaction with other nematodes species or genus) and their sensitivity (detection of a single juvenile or mixed with other species). The species-specific PCR proved to be more sensitive but less specific than the SCAR PCR. The PCR-RFLP enables the identification of several Meloidogyne species but profile analysis can be difficult when several species are present in the mixture. Specific PCR products and RFLP profiles were also observed for M. arenaria and M. enterolobii, and described for M. minor and M. artiellia. 相似文献
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ABSTRACT Polymerase chain reaction amplification of the intergenic spacer region between the 5S and 18S genes from Meloidogyne chitwoodi, M. fallax, and M. hapla enabled these three important temperate species to be differentiated. Length polymorphism was found between M. chitwoodi and M. fallax as a result of differing numbers of short repeats located between the 5S and 18S genes. The presence of the 5S gene within the rDNA cistrons was confirmed in the Meloidogyne spp. included in this study. The region between the 28S and 5S genes for M. chitwoodi and M. fallax was short and lacked variability in repeated sequences compared with the main tropical Meloidogyne spp. and M. hapla. Differences in the number of these repeats resulted in intraspecific length polymorphism for M.hapla. 相似文献