In 2013, during a field survey conducted in Portugal on potato, Solanum tuberosum, an unusual esterase (EST) phenotype was detected in a root‐knot nematode (RKN) from potato roots collected in Coimbra. This Portuguese isolate was purified and maintained on tomato, S. lycopersicum, and morphological, biochemical and molecular characteristics were studied. Perineal pattern morphology was highly variable, similar to Meloidogyne ethiopica and not useful for identification. The EST phenotype, from young egg‐laying females, displayed three bands similar to the Brazilian M. luci (L3) and distinct from M. ethiopica (E3). Phylogenetic analyses of mitochondrial cytochrome oxidase subunit I and the mitochondrial DNA region between COII and 16S rRNA genes revealed that the Portuguese isolate grouped with M. luci isolates close to M. ethiopica isolates. However, considering the ITS1‐5.8S‐ITS2 region, the Portuguese isolate grouped with isolates of M. luci, M. ethiopica and M. hispanica, which limits the confidence of this region for M. luci diagnosis, and its differentiation from other species with morphological similarities. The M. luci pathogenicity to potato was also assessed in 16 commercial cultivars and compared with M. chitwoodi, considered to be a quarantine RKN species by EPPO. All potato cultivars were susceptible to both Meloidogyne species with gall indices of 5 and higher reproduction factor values ranging from 12.5 to 122.3, which suggests that M. luci may constitute a potential threat to potato production. In the present study, M. luci is reported for the first time attacking potato in Portugal.

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Maleita, C. M., Simoes, M. J., Egas, C, Curtis, R. H. C, and Abrantes, I. M. de O. 2012. Biometrical, biochemical, and molecular diagnosis of Portuguese Meloidogyne hispánica isolates. Plant Dis. 96:865-874.Meloidogyne hispánica infects many economically important crops worldwide. The accurate identification of this pathogen is essential for the establishment of efficient and sustainable integrated pest management programs. Portuguese M. hispánica isolates were studied by biometrical, biochemical, and molecular characteristics. Biometrical characteristics of M. hispánica females, males, and second-stage juveniles were similar to the original description. Biochemical studies revealed a unique enzyme pattern (Hi4) for M. hispánica esterases that allowed for species differentiation. Molecular analysis of the mtDNA region from COII and 16S rRNA genes resulted in amplification products (1,800 bp) similar to M. hispánica, M. ethiopica, and M. javanica, and the described Hinñ was unable to discriminate M. hispánica from the other two species. Analysis of the mtDNA sequences revealed altered nucleotides among the isolates that created new restriction sites for Alul and Dralll. The resulting restriction patterns successfully discriminated between the three species, providing a new tool for Meloidogyne identification. Finally, the phylogenetic relationship between M. hispánica and several Meloidogyne spp. sequences was analyzed using mtDNA, confirming the divergence between meiotic and mitotic species and revealing the proximity of M. hispánica to closely related species. Based on the studies conducted, the application of isozyme or polymerase chain reaction restriction fragment length polymorphism analysis would be a useful and efficient methodology for M. hispánica identification.The "Seville root-knot nematode", isolated from peach rootstock {Prunus pérsica (L.) Batsch) in Spain, was studied for the first time by Dalmasso and Berge (17) and described later as Meloidogyne hispánica Hirschmann, 1986 (27). This species has a woridwide distribution, and has been reported infecting economically important crops in Africa (22,34,48), Asia (21), Australia (21), Europe (4,21,31,49), and North, Central, and South America (10,15,21).M. hispánica is cytologically similai-to the diploid race of M. arenaria, and morphologically very close to M. arenaria, M. floridensis, and M. incognita (13,25,27). When tested using the North Carolina differential host test, M. hispánica isolates have host responses similar to M. arenaria race 2 or M. javanica (4,13), M. arenaria race 1 or M. incognita race 2 (4,27), and M. incognita race 3 (4), showing an intraspecific variability among the isolates of this species. The identification of M. hispánica only on the basis of morphological characteristics, especially on perineal patterns, or on the pattern of disease reacfions induced in the North Carolina differential hosts, is very difficult. One isolate of M. hispánica from South Africa was erroneously associated with M. arenaria thamesi on the basis ...

Naphthoquinones exhibit important biological activities and are present in walnut husk residues in significant amounts. However, their potential as alternatives to synthetic nematicides has not been fully explored. This work aimed to assess the effects of pure naphthoquinones (juglone; 1,4-naphthoquinone; plumbagin) on the mortality of the root-knot nematode Meloidogyne hispanica second-stage juveniles (J2). Extracts from Juglans spp. walnut husks were characterized, and the effects of J. nigra extracts on attraction and life cycle of M. hispanica were evaluated. 1,4-Naphthoquinone was the most effective compound causing 42% J2 mortality at 50 ppm. The extract from in natura J. nigra walnut husks presented similar effects on J2 mortality to those observed for pure 1,4-naphthoquinone. The extract from dried husks was repellent and reduced nematode root penetration but did not affect reproduction. Therefore, walnut residues can be valorized as renewable sources of naphthoquinone-based products and potentially employed as bionematicides against Meloidogyne spp.

The reproduction of a Meloidogyne hispanica isolate from Portugal was evaluated in 63 plant species/cultivars, in pot assays at 25±2.0°C, on the basis of root gall index (GI) and reproduction factor (Rf0final/initial egg density) at 60 days after inoculation. Cultivars of aubergine, bean, beetroot, broccoli, carnation, corn, cucumber, French garlic, lettuce, melon, onion, parsley, pea, potato, spinach, and tobacco and two of cabbage were susceptible (3≤GI≤5; 1.15≤ Rf≤262.86). Cabbage cv. Bacalan, cauliflower cv. Temporão and pepper cv. Zafiro R2 were hypersusceptible or poor hosts (Rf<1; GI>2) and pepper cvs. Aurelio and Solero were resistant (0.0 ≤ GI ≤ 0.4; 0.00≤Rf≤0.03). The response of the pepper cultivars and the Mi-1 resistant tomato cv. Rossol was also conducted in pots using two inoculum levels and four temperatures, three growth chamber (25±2.7°C, 29.3±1.8°C and 33.6±1.2°C) and one outdoors (24.4±8.2°C). At 24.4±8.2°C and 25±2.7°C, the reproduction on the resistant tomato was significantly lower compared to the susceptible cv. Easypeel. At all temperatures, resistance was evident for the pepper cultivars, despite the fact they were not found to contain any of the Me1, Me3, Me7 and N genes. The eggs obtained on cv. Aurelio at 33.6± 1.2°C were used to get a selected resistance breaking isolate of M. hispanica that was able to reproduce on the three pepper cultivars. Our results suggest that the initial M. hispanica isolate is a mixture of virulent and avirulent individuals. The pepper cultivars tested, have potential to reduce M. hispanica populations in agro-ecosystems under certain conditions, but they should be used as a part of an integrated management strategy in order to prevent the development of virulent populations.