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The Mi-1.2 gene confers resistance to a wide range of Meloidogyne species, being the most important resistance factor employed in tomato breeding so far. However, many aspects related to the interaction of Mi-1.2-carrying tomato cultivars and virulent/avirulent Meloidogyne populations have not yet been clarified. Herein, comparative histopathological analyses were carried after inoculation of the homozygous (Mi-1.2/Mi-1.2) tomato rootstock 'Guardião' and the susceptible cultivar 'Santa Clara' (mi-1.2/mi-1.2) with virulent and avirulent populations of M. javanica. In the susceptible control, it was possible to visualize second stage juveniles (J2) of avirulent population and feeding sites from 2 to 30 days after infection (DAI) with females reaching maturity at 24-34 DAI. In the resistant rootstock, the Mi-1.2 gene-mediated resistance was related mainly to early defense responses (pre-infection and hypersensitive reaction), which led to an immunity-like phenotype that completely prevented the reproduction of the avirulent Meloidogyne population. On the other hand, J2s of the virulent M. javanica population were able to penetrate roots much more than the avirulent population, migrated and developed normally, showing intense and similar pattern of penetration from 4 to 34 DAI in the root tissues of both resistant and susceptible tomato genotypes. The total numbers of J2, J3, J4, and females counted in 'Santa Clara' for the virulent population of M. javanica were higher than in 'Guardião'. [ABSTRACT FROM AUTHOR]

A new root‐knot nematode (RKN), Meloidogyne izalcoensis, was detected on coffee in Brazil. This species was first described on coffee from El Salvador and later detected in Asia and Africa. There are no reports on the genetic diversity of this species and resistance to M. izalcoensis has not yet been studied in coffee cultivars. All populations were identified by esterase phenotype and sequence‐characterized amplified region (SCAR) species‐specific markers. Based on random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) markers, low intraspecific variability was detected among M. izalcoensis populations from Africa, Vietnam and Brazil, but the population from El Salvador showed fewer genetic differences from the other populations. Phylogenetically, all populations of M. izalcoensis from different locations (El Salvador, Kenya, Tanzania, Vietnam and Brazil) grouped with 90% and 69% bootstrap support for COII and HSP90 regions, respectively, indicating that these markers are highly conserved for the species. In addition, both markers enabled separation of M. izalcoensis populations from other important coffee Meloidogyne species, including M. exigua, M. paranaensis, M. incognita, M. arabicida and M. lopezi. In resistance studies, most genotypes tested that had resistance to other Meloidogyne spp. (Amphillo × Catuaí, Hybrid of Timor, IAPAR 59, IPR 99, IPR 100, IPR 102, IPR 103, IPR 105, IPR 106, IPR 107 and IPR 108) were found to be susceptible to M. izalcoensis, except for the rootstock cv. Apoatã IAC 2258, which proved to be moderately resistant, with a genetic segregation for this character of 43.8%. [ABSTRACT FROM AUTHOR]

The root‐knot nematodes are the most devastating worms to worldwide agriculture with Meloidogyne incognita being the most widely distributed and damaging species. This parasitic and ecological success seems surprising given its supposed obligatory clonal reproduction. Clonal reproduction has been suspected based on cytological observations but, so far, never confirmed by population genomics data. As a species, M. incognita is highly polyphagous with thousands of host plants. However, different M. incognita isolates present distinct and overlapping patterns of host compatibilities. Historically, four "host races" had been defined as a function of ranges of compatible and incompatible plants. In this study, we used population genomics to assess whether (a) reproduction is actually clonal in this species, (b) the host races follow an underlying phylogenetic signal or, rather represent multiple independent transitions, and (c) how genome variations associate with other important biological traits such as the affected crops and geographical distribution. We sequenced the genomes of 11 M. incognita isolates across Brazil that covered the four host races in replicates. By aligning the genomic reads of these isolates to the M. incognita reference genome assembly, we identified point variations. Analysis of linkage disequilibrium and 4‐gametes test showed no evidence for recombination, corroborating the clonal reproduction of M. incognita. The few point variations between the isolates showed no significant association with the host races, the geographical origin of the samples, or the crop on which they have been collected. Addition of isolates from other locations around the world confirmed this lack of underlying phylogenetic signal. This suggests multiple gains and losses of parasitic abilities and adaptations to different environments account for the broad host spectrum and wide geographical distribution of M. incognita and thus to its high economic impact. This surprising adaptability without sex poses both evolutionary and agro‐economic challenges. [ABSTRACT FROM AUTHOR]

The type population of Meloidogyne brasiliensis is synonymised under M. ethiopica based on morphological and morphometric similarities, as well as through biochemical, molecular and phylogenetic studies. Meloidogyne ethiopica was first described in 1968 in Tanzania using specimens from a single egg mass culture on tomato and re-described in 2004 using an isolate from Brazil. Meloidogyne brasiliensis was described in 2002 in Brazil based on specimens collected from tomato (type population) and pea. Morphological and morphometric studies of their descriptions showed important similarities in major characters as well as some general variability in others. Characterisation of esterase isozyme phenotypes of three populations of M. ethiopica from Brazil, Chile and Kenya, and two M. brasiliensis populations, resulted in only one esterase pattern (E3), a phenotype already known for M. ethiopica. In PCR assays, the species-specific 350 bp SCAR marker developed for M. ethiopica was amplified from the M. brasiliensis populations tested. In phylogenetic analyses based either on sequences of the ITS1-5.8S-ITS2 and D2-D3 (28S) rRNA regions or on RAPD and AFLP data, the populations of both species clustered together with a strong bootstrap support. Altogether, these results provide congruent evidence that M. brasiliensis is not a valid species but rather a junior synonym of M. ethiopica. [ABSTRACT FROM AUTHOR]

Root-knot nematodes (RKN) are important plant pathogens affecting rice in South-East Asia and southern Brazil in irrigated rice fields. In order to investigate the specific diversity of RKN associated with irrigated rice in southern Brazil, Meloidogyne spp. from Rio Grande do Sul (RS) and Santa Catarina (SC) States were characterised biochemically by esterase (Est) and malate dehydrogenase (Mdh) phenotypes. Fifty-six Meloidogyne spp. populations were detected in 48% of rice samples, and a total of five esterase phenotypes were identified, four of which presented as drawn-out bands in different positions. In RS State, M. graminicola (Est VS1), Meloidogyne sp. 2 (Est R2) and Meloidogyne sp. 3 (Est R3) were identified, which corresponded to ca 80, 40 and 10% of samples, respectively. In SC State, M. graminicola, M. javanica (Est J3), Meloidogyne sp. 1 (Est R1), Meloidogyne sp. 2 and Meloidogyne sp. 3 accounted for ca 93.75, 12.50, 62.50, 12.25 and 6.25% of samples, respectively. The esterase phenotypes R1, R2 and R3 are new, never having been detected on rice before. Meloidogyne javanica showed a N1 Mdh phenotype (Rm: 1.0), while four other populations exhibited a N1a (Rm: 1.4) phenotype. All populations were tested with two SCAR markers specific to M. graminicola, which confirmed that, but no specificity was obtained with both markers in relation to the atypical populations analysed. Sequencing and phylogenetic analyses of internal transcribed spacer-rRNA (ITS) were performed to infer the phylogenetic relationship of these atypical Meloidogyne spp. populations. Meloidogyne sp. 1 grouped with the mitotic parthenogenetic species, while the two others (Meloidogyne sp. 2 and sp. 3) clustered with M. graminicola and other meiotic parthenogenetic species. Taken together, these data highlight the unprecedented specific diversity of RKN associated with irrigated rice in southern Brazil. Further morphological and phylogenetic studies involving these atypical isolates will be carried out to identify this complex of species. [ABSTRACT FROM AUTHOR]

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In a survey for Meloidogyne spp. in different crops from 11 regions in Ceará State, Brazil, using esterase isozyme electrophoresis as a specific identification method, four atypical populations were characterised from cabbage, papaya, noni and canapum plants, all of which showed an esterase profile different from those previously detected in Brazil. Morphological studies showed typical characteristics of Meloidogyne konaensis. Perineal patterns of females were variable, similar to M. arenaria and M. incognita, stylet length 14-20 Qm. In females, the knobs gradually merged with the shaft and the dorsal pharyngeal gland orifice (DGO) ranged from 4 to 7 Qm. Although males are not frequently found, the stylet morphology provides the most useful source of diagnostic character for the species, having 6-12 large projections protruding from the shaft. The esterase pattern K3 is unique and species-specific with three major bands Rm 1.0, 1.17, 1.27 and a secondary band Rm 1.10. Some confusion about the true identity of this species was clarified in this study, including differentiation from M. paranaensis. A species-specific SCAR marker developed for M. paranaensis was tested and no amplification products were observed. In Neighbour-Joining analyses of ITS and D2-D3 rRNA sequences, M. konaensis from Brazil appeared clearly separated from M. paranaensis. Pathological tests indicated that coffee is not a host of M. konaensis as previously reported in the original description of this species. [ABSTRACT FROM AUTHOR]

Summary -- A significant portion of the Cerrado (Brazilian savanna) has been replaced by major crops such as soybean. This may reveal populations of nematodes with different genetic backgrounds compared to cultivated fields. The objectives of this study were to evaluate the genetic variability and aggressiveness of isolates of Meloidogyne spp., contrasting nematodes from preserved areas of the Cerrado with those originating from cultivated soybean fields. Cluster analysis separated isolates of Meloidogyne spp. and isolates from Cerrado and soybean but did not separate an aggressive Meloidogyne morocciensis isolate. The aggressiveness of six selected populations of Meloidogyne spp. from Cerrado and soybean against soybean cultivars was evaluated. Results showed that populations of M. javanica and M. incognita from Cerrado and soybean showed similar aggressiveness. However, for M. morocciensis, the population from soybean was much more aggressive than the one from Cerrado. Aggressiveness is a very intriguing subject that needs special attention for future research in nematology. [ABSTRACT FROM AUTHOR]

The Cerrado biome represents a hotspot of biodiversity. Despite this, the nematofauna in this biome has not been well characterized, especially that related to root-knot nematodes. This work aimed to identify Meloidogyne species present in different cerrado vegetations and to investigate potential hosts of Meloidogyne javanica in this biome. Soil samples (250) were collected in native areas of cerrado vegetation located at the National Park of Brasília ( PNB) (125 samples) and Água Limpa Farm ( FAL) (125 samples), and transferred to sterile pots. Single tomato plants cv. Santa Clara (susceptible) were transplanted into individual pots and maintained for 90 days under glasshouse. Females of Meloidogyne spp. were extracted from tomato roots and identified based upon esterase phenotypes and confirmed with PCR using specific sequence characterized amplified regions ( SCAR) primers. Native plants were inoculated with 10 000 individuals (eggs + J2) of a pure culture of M. javanica and maintained under glasshouse for 6 months. From the 250 samples collected, 57 (22.8%) presented Meloidogyne spp. A total of 66 Meloidogyne populations were identified as follows: M. javanica (75.76%), M. incognita (10.60%), M. hapla (9.1%), M. morocciensis (3.03%) and M. arenaria (1.51%). The following esterase phenotypes were detected: M. javanica (J3 and J2), M. incognita (I1 and I2), M. hapla (H1), M. morocciensis (A3) and M. arenaria (A2). The SCAR primers incK14F/incK14R, Fjav/Rjav and Fh/Rh amplified specific fragments in M. incognita (399 bp), M. javanica (670 bp) and M. hapla (610 bp) and can be used for identification of indigenous Meloidogyne spp. from cerrado. The primer set Far/Rar is not specific for M. arenaria due to the amplification of DNA in M. morocciensis. Mimosa caesalpiniifolia was the only native plant in which M. javanica developed a high reproductive rate, and it is probably a host for this nematode in cerrado. [ABSTRACT FROM AUTHOR]

A new root-knot nematode parasitising vegetables, flowers and fruits in Brazil, Iran and Chile, is described as Meloidogyne luci n. sp. The female has an oval to squarish perineal pattern with a low to moderately high dorsal arc and without shoulders, similar to M. ethiopica. The female stylet is robust and 15-16 pm long; the distance from the dorsal pharyngeal gland orifice to the stylet base (DGO) is 3-4 p.m. Males have a high, rounded head cap continuous with the body contour. The labial disc is fused with the medial lips to form an elongated lip structure. The head region is not marked by incomplete annulations. Male stylet robust, 20.8-23.0 p.m long with rounded knobs; the DGO is 2.5-4.5 p.m. The stylet of second-stage juveniles (J2) is 12.0-13.5 pm long and the DGO to the stylet base is 2.3-3.3 /xm. The J2 tail is conoid with finely rounded terminus and is 40.0-48.5 //m long. Biochemically, the esterase phenotype L3 (R nv 1.05, 1.10, 1.25) is unique and is the most useful character to differentiate M. luci n. sp. from all other Meloidogyne species. Reproduction is by mitotic parthenogenesis (2rc = 42-46 chromosomes). In a differential host test, the population from Lavandula spica, Caxias do Sul, RS State, Brazil, reproduced on tomato cv. Rutgers, tobacco cv. NC95 and pepper cv. California Wonder. No reproduction occurred on watermelon cv. Charleston Gray, cotton cv. Deltapine 61 or peanut cv. Florunner. In Neighbour-Joining analyses of ITS and D2-D3 rRNA sequences, populations of M. luci n. sp. from Brazil, Chile and Iran clustered together and were clearly separated from other Meloidogyne spp., thus confirming that all three populations are very similar and conspecific. [ABSTRACT FROM AUTHOR]

Females, males and second-stage juveniles of an unusual population of Meloidogyne exigua race 3 that only parasitises the rubber tree were examined by light and scanning electron microscopy. Previous molecular characterisation, using SCAR markers, showed consistency with other M. exigua populations from coffee. However, RAPD analysis showed high polymorphism (43.1-57.8%) but with 100% bootstrap support among populations from coffee and rubber tree. In addition, this population showed the main M. exigua esterase band (Rm: 1.5) and an additional band (Rm: 1.6) not detected in the coffee population. The morphology of this atypical population was very close to M. exigua from coffee in major diagnostic characters such as perineal pattern and male head region. However, minor differences occurred in morphological and morphometric features, particularly in the female and male stylet morphology. Cytogenetic studies confirmed the occurrence of meiotic parthenogenesis with haploid chromosome number (n = 18). [ABSTRACT FROM AUTHOR]

A root-knot nematode parasitising yakon (Polymia sonchifolia) in São Paulo State, Brazil, is identified as Meloidogyne inornata. The species is redescribed from this material and compared with the original description of M. inornata. The female perineal patterns have a distinct, high, dorsal arch composed of smooth to wavy striae, similar to Meloidogyne incognita. The female stylet is 15.0-17.0 μm long with the cone generally slightly curved dorsally and with well developed knobs. DGO is 3.5-4.5 μm. Males have a high, rounded, head cap that is continuous with the body contour and has a large, round, centrally concave, labial disc raised above the medial lips. The head region is never marked by incomplete annulations and the stylet is robust, 20.0-25.0 μm long, with a straight cone, cylindrical shaft with several small projections and pear-shaped, backwardly sloping knobs. The stylet length of second-stage juveniles is 10.0-13.0 μm, DGO is 2.5-3.5 μm, tail length is 35.0-58.0 μm and c = 6.7-13.9. Biochemically, the esterase phenotype I3 (= Y3) is species-specific and is the most useful character for differentiating M. inornata from other Meloidogyne species. Reproduction is by mitotic parthenogenesis, 3n = 54-58. In a soybean test, cv. Abura was susceptible and cv. LA411219 was highly resistant. As the type material is lost, a neotype female is formally designated. [ABSTRACT FROM AUTHOR]

An obligate parasite bacterium of the root-knot nematode, Pasteuria penetrans strain P10, isolated from Meloidogyne incognita females on banana roots in Imperatriz Maranhão State, Brazil, was evaluated in glasshouse conditions, using two doses of a dry root bionematicide (107 endospores (5.0 g/seedling) and 106 endospores (0.5 g/seedling)) on seedlings of cv. Mundo Novo coffee. The soil in which coffee seedlings were raised was inoculated previously with these two doses of P. penetrans and after 2 months the plants were transferred to soils of different textures: clay-sandy soil (38% clay, 2% silt and 60% sand) and sandy soil (17% clay, 0% silt and 83% sand). When the coffee plants were 30 cm high, they were inoculated with 20 000 eggs/plant of M. incognita race 1. The coffee plants were examined 8, 16 and 24 months after nematode plant infestation. The effectiveness of the biological control was determined by the reduction of nematode reproduction factor, which ranged from 62 to 67% in clay-sandy soil and 80 to 85% in sandy soil. The mechanism of suppression caused by the bacterium was evaluated by the percentage of infected second-stage juveniles (J2), number of endospores attached/J2 and number of infected females. The high levels of suppression were related to time, increasing from 8 to 24 months, and to the percentage of sand in the soil. [ABSTRACT FROM AUTHOR]

Enzyme phenotypes, specifically esterases (EST) and malate dehydrogenase (MDH), were used to characterise different species of Meloidogyne from Chile. Esterase activity was highly polymorphic and was the most useful in the identification of the different species. Using this enzyme it is possible to characterise and identify M. ethiopica in about 80% of samples on grapevine, kiwi and tomatoes. Another three species, M. javanica, M. hapla and M. arenaria, were identified on tomatoes, kiwi and pomegranate with only one or a few populations. It was possible to detect minor atypical (unidentified) phenotypes, generally in mixed populations with M. ethiopica. Only the profiles N1 and H1 of MDH were detected. N1 was not specific and H1 allowed identification of M. hapla. Contaminated nursery stock has probably resulted in serious infestation by M. ethiopica in vineyards in various localities in Chile. [ABSTRACT FROM AUTHOR]

A new root-knot nematode parasitising coffee in the region of the Izalco volcano, Sansonate, El Salvador, is described as Meloidogyne izalcoensis n. sp. The suggested common name is El Salvador coffee root-knot nematode. The perineal pattern is characterised by the moderately high to high, squareish to rounded, dorsal arch, striae coarse, smooth to wavy, sometimes zigzaggy, usually without a distinct whorl, and similar to that of M. incognita and M. paranaensis. The female head region set off from body, sometimes annulated, and the labial disc has two prominent elevations or bumps on the ventral side that are slightly raised above the medial lips. The female stylet is robust, 15.0-16.0 μm long and with the DGO at 4.5-6.0 μm posterior to the knobs. Males have a high, round, head cap continuous with the body contour and the labial disc is fused with the medial lips to form an elongated structure. The head region is never marked by incomplete annulations. The stylet is robust, 23.0-26.0 μm long, and has rounded, backwardly sloping, knobs with the DGO located at 4.0-7.0 μm posteriorly. The stylet of second-stage juveniles is 12.0-13.0 μm long and the DGO is located 3.0-4.0 μm posterior to the stylet base; the tail is 45-48 μm long, conoid, with a rounded terminus. Biochemically, the esterase phenotype I4 (= Sa4) (Rm: 0.86, 0.96, 1.24, 1.30) is unique and is the most useful character to differentiate M. izalcoensis n. sp. from all other species. [ABSTRACT FROM AUTHOR]

The 18S rDNA of 19 populations of Meloidogyne spp. was amplified and directly sequenced. The region of mitochondrial DNA, located in the 3′ portion of the gene that codes for cytochrome oxidase subunit II (COII) through a portion of the 16S rRNA (lRNA) gene, from 16 of these populations was cloned and sequenced. Heteroplasmic sequences were identified from both rDNA and mtDNA regions for several taxa. Several sequences sampled from nominal taxa differed from previously published accounts. Phylogenetic trees based on alignments of these sequences were constructed using distance, parsimony and likelihood optimality criteria. For 18S rDNA data, three main clades were identified. One well supported clade (86–91% bootstrap) included the most common and widely disseminated species, e.g.,M. arenaria, M. javanica and M. incognita, some recently described or redescribed species (M. floridensis, M. paranaensis, and M. ethiopica) plus numerous unidentified isolates. All mitotic parthenogenetic species, except for M. oryzae, were included in this clade. Other, less well supported clades included the amphimictic and facultative meiotic species M. hapla, M. microtyla, M. maritima and M. duytsi. One such clade comprised three meiotic parthenogens (M. exigua, M. graminicola and M. chitwoodi) and M. oryzae. This clade was moderately supported (77% bootstrap) but the relationships within this clade were poor. For mitochondrial DNA data, only the species in clade I from rDNA analysis, and M. hapla were analysed. These species formed a well supported clade (100% bootstrap) to the exclusion of M. mayaguensis and M. hapla. The addition of taxa and mtDNA data to publicly available records improved the discrimination sensitivity of species and atypical, non-identified, isolates. [ABSTRACT FROM AUTHOR]

The present study was based on 18 populations of Meloidogyne spp. originating from different coffee fields in Brazil, Central America and the USA (Hawaii). The identification of the main species and an outline of the diversity of root-knot nematodes parasitising coffee in these countries with respect to esterase phenotypes, morphology and molecular polymorphism, are provided. With the present electrophoretic procedure, esterase phenotypes were demonstrated to be species-specific and constitute a good tool for identifying root-knot species from coffee, viz., M. incognita (Est I1, I2), M. paranaensis (Est P1, P2), M. arenaria (Est A2), M. arabicida (Est AR2), M. exigua (Est E1), M. mayaguensis (Est M2) and two unknown populations that probably represent new species (Est SA2, SA4). The perineal pattern is often an unreliable character when used alone for making diagnostic conclusions but, when used as a complementary tool together with enzyme characterisation, is essential for checking the morphological consistency of the identification. Male characters are important for confirming the diagnosis of some species, such as M. paranaensis, M. konaensis and M. incognita. The results showed that the RAPD markers produced are consistent with other approaches (esterase phenotypes and morphological features) for confirming species identification and for estimating genetic relationships among species and isolates. Phylogenetic analyses showed that M. mayaguensis and M. exigua are more closely related to one another than they are to the other species. This was also true for M. javanica, M. arenaria and Meloidogyne spp. Low levels of intraspecific polymorphism were detected in M. exigua (8.6%), M. incognita (11.2%) and M. paranaensis (20.3%). Conversely, M. arenaria and the two unknown Meloidogyne spp. exhibited higher levels of intra- or interspecific variability (34.9 and 29.9%, respectively). [ABSTRACT FROM AUTHOR]

Esterase phenotypes were used to characterise 25 populations of Meloidogyne spp. collected on bananas from different banana producing areas in Brazil, using a simplified technique for routine analysis. Meloidogyne javanica, M. incognita, M. arenaria, and Meloidogyne spp. were detected at percentages of 61.7, 32.2, 4.3 and 1.8, respectively. The Meloidogyne populations represented mixed species in 80% of the samples, M. javanica and M. incognita prevailing under field conditions. Genetic analyses were conducted using RAPD markers which provided, alone or in combination, reliable polymorphisms both between and within species. Based on the presence or absence of bands, RAPD analysis of the data resulted in clustering of species and isolates congruent with esterase phenotype characterisation. The intraspecific variability in M. javanica, M. incognita and M. arenaria represented 29.1, 19.5 and 40.2% of the polymorphic amplified fragments, respectively. A general lack of correlation was observed between banana cultivar group, geographical origin and differentiation of the nematodes. [ABSTRACT FROM AUTHOR]

A root-knot nematode parasitising kiwi fruit (Actinidia deliciosa) in Rio Grande do Sul State, Brazil and grape-vine (Vitis vinifera) in Chile, is identified as Meloidogyne ethiopica Whitehead, 1968. The species is redescribed from this new material and compared with the type description of M. ethiopica and another population of the species from Kenya. The female has an oval to squarish perineal pattern with a moderately high to high dorsal arch, smooth, widely spaced striae, and no 'shoulders'. The head region is set off with an elevated squarish labial disc, usually marked by annulations, and the stylet is 12-15 μm long, the cone usually being slightly curved dorsally and the shaft gradually widening posteriorly to near the junction with the rounded stylet knobs. The DGO is 3.0-5.0 μm behind the knobs. The male has a high, rounded head cap which is continuous with the body contour and has a distinct labial disc, almost circular to hexagonal in shape, and distinctly separated from the medial lips. The stylet is robust, 23-27 μm long with a straight cone and a cylindrical shaft widening slightly near its junction with the basal knobs which are smooth, round to pear-shaped and backwardly sloping. The stylet length of the second-stage juvenile is 11-14 μm, the DGO is 2.0-3.0 μm behind the knobs and the tail length is 52-72 μm. Biochemically, the esterase phenotype E3 ( Ki3) is species-specific and is the most useful character for differentiating M. ethiopica from other species. Reproduction is by mitotic parthenogenesis, 2n 36-38. In a differential host test, populations of M. ethiopica reproduced on tomato, tobacco, pepper and watermelon. No reproduction occurred on cotton or peanut. Using the PCR-RAPD analysis to compare populations from Brazil, Chile and Kenya, a low proportion of polymorphic fragments (about 17.7%) was detected and the isolates clustered together with high bootstrap support (100%), thus confirming that all three populations are very similar and apparently conspecific. [ABSTRACT FROM AUTHOR]

Pasteuria penetrans isolates from different geographical areas were tested for the ability of endospores to attach to secondstage juveniles and to colonise females of different populations of Meloidogyne spp. from coffee and other crops. Our results confirm that the spore attachment test cannot be used as the only criterion for screening for the efficiency of the bacterial isolate against nematodes. The percentage of females infected with the bacteria and the endospore concentration in 100 macerated females were the best approaches for screening the highly pathogenic isolates. Using these parameters, it was possible to select some isolates for M. javanica and M. arenaria race 2; one isolate, P12, for the three populations of M. paranaensis, and isolate P10 for the four races of M. incognita from coffee. The isolates exhibited poor pathogenicity on M. hapla, M. exigua, M. graminicola and M. mayaguensis. There was clear evidence that the greatest parasitism occurred when the isolates of P.penetrans were exposed to species of Meloidogyne that were genetically close to that from which the bacteria populations had been originally isolated. The dendrogram obtained from attachment of 18 P. penetrans isolates on 13 Meloidogyne spp. populations clearly defined subgroups of the bacteria related to their geographical origin. RAPD analyses were used for fingerprinting the genomes of P.penetrans isolates. Twenty 10-mer oligonucleotide primers of arbitrary sequence revealed 145 scorable binary characters. Cluster analysis showed a low (61%) to high (80%) level of genetic similarity among the isolates and that phenetic groups were sometimes related to pathogenicity. [ABSTRACT FROM AUTHOR]