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The aim of this study was to characterize Meloidogyne paranaensis populations collected from infested coffee crops. Methodologies used to characterize the 11 studied populations from municipalities in Paraná and Minas Gerais States involved the morphological analysis of perineal patterns, biochemical analysis by isozyme electrophoresis, sequencing of internal transcribes spacer 1 (ITS-1) and D2/D3 ribosomal DNA (rDNA) regions, reproductive fitness, and virulence characterization in coffee genotypes. Morphological evaluations showed the existence of variation between populations, although the majority of them showed typical perineal patterns. The biochemical identification was based on α-esterase isozyme analyses and resulted in the appearance of three distinct profiles: P1 (typical), P2 (atypical), and a nondescribed profile, P2b. BLAST of the ITS-1 and D2/D3 rDNA regions indicated homology (>95%) with other sequences deposited in GenBank. For reproductive fitness and virulence characterization, 13 coffee genotypes (5 Coffea arabica and 8 C. canephora) were inoculated with 11 M. paranaensis populations. Variation in the reproductive fitness of populations was observed for cultivar Mundo Novo, a genotype without resistance genes, and variation in the virulence of populations was observed in genotypes carrying resistance genes. Three populations exhibited virulence combined with high reproductive fitness, while one showed virulence with low reproductive fitness. Some hosts were resistant to 11 populations, while one of the hosts was resistant to only one population, indicating the presence of different resistance genes. Nevertheless, no relationship was observed between the origin of population and their variations in perineal patterns, esterase profiles, phylogeny, or reproductive fitness in coffee genotypes, or between the different characterizations, although differences were observed within each characteristic.

Abscisic acid (ABA) is a classical hormone involved in the plant defense against abiotic stresses, especially drought. However, its role in the response against biotic stresses is controversial: it can induce resistance to some pathogens but can increase the susceptibility to other ones. Information regarding the effect of ABA in the relationship between plants and sedentary phytonematodes, as Meloidogyne paranaensis, are scarce. In this study, we reported ABA changing Arabidopsis thaliana susceptibility level against M. paranaensis. The population of M. paranaensis was reduced 58.3% with the application of exogenous ABA 24 hours before the nematode inoculation, which demonstrated that this phytohormone plays a role in the pre-infectional defense of A. thaliana against this root-knot nematode. The increases in the nematode population densities in the ABA biosynthesis mutant, aba2-1, corroborated the results observed with the exogenous application of ABA. The phytohormone did not show nematicide or nematostatic effects on M. paranaensis juveniles in in vitro tests, indicating that the response is linked to intrinsic plant factors, which was corroborated by the decrease in the number of nematodes in the abi4-1 mutant. This reduction indicates that the gene expression regulation by transcript factors possibly is related to regulatory cascades mediated by ABA in the response of A. thaliana against M. paranaensis.

The objective of this work was to evaluate the development and reproduction of Meloidogyne paranaensis in three Arabic coffee genotypes, IPR 106, resistant; Mundo Novo IAC 376-4, susceptible; and IAPAR 88480-8-4, with intermediate levels of resistance. To evaluate the penetration and the development of M. paranaensis in the coffee genotypes, plants were inoculated with 3000 eggs, and evaluations were performed at 5, 10, 15, 20, 25, 30, 35, and 40 days after inoculation (DAI). To evaluate the nematode multiplication, 1000 eggs were inoculated, and the evaluations were performed at 60, 90, 120, 150, 180, 210, and 240 days after inoculation (DAI), when the reproduction factor (RF) and the number of nematodes per gram of roots were obtained. We can conclude that IAPAR 88480-8-4, despite the delay caused in the development of the nematode, did not show the intermediate level of resistance, as previously reported, and Mundo Novo and IPR 106 behavior as susceptible and resistant genotypes. The adjustment of the behavior of the variable RF showed that, only after 120 DAI, RF values were high, suggesting that the evaluations should be performed between 120 and 180 DAI, to obtain more consistent results.

Aphelenchoides besseyi is the causal agent of soybean green stem and foliar retention syndrome known as “Soja Louca II.” This nematode has recently been reported parasitizing cotton in Brazil. In Costa Rica, it causes the symptoms known as “amachamiento” and false angular spots in common bean (Phaseolus vulgaris). Due to the great importance of beans to Brazilian agriculture, the objective of this research was to study the pathogenicity of A. besseyi in common bean under greenhouse conditions, including its endoparasitic relationships by staining root and shoot system tissues with fuchsin acid. In addition, A. besseyi was collected and quantified from shoot systems 30 days after inoculation by washing the tissue in water and blender centrifugal flotation. We observed the symptoms of amachamiento, leaf and vein deformation in the expanded trifoliate leaves, and also leaves with necrotic, brown to reddish and angular lesions, characteristics from false angular spot, and deformed stems characterized by enlargement of nodes, retortions, and necrotic lesions. High numbers of nematodes were found inside common bean plants. This is the first report of the pathogenicity and symptoms caused by A. besseyi in common bean in Brazil. These findings are important for development of management strategies to avoid losses on bean cropped in infested areas.

Meloidogyne paranaensis is an important root-knot nematode species for several crops in Brazil, especially coffee. Despite such notoriety, studies with this pathosystem are time and space consuming. Although Arabidopsis thaliana is widely used for genetics, physiological and biotic/abiotic stress studies, no information was found regarding M. paranaensis relationships with this model plant. The objective of this study was to optimize methodologies to study the interactions between M. paranaensis and plants, using A. thaliana as model plant. Columbia-0 (Col-0) ecotype was challenged with M. paranaensis to evaluate the penetration rates and nematode reproduction factor. Besides, nematode initial populations and plant ages for inoculation were tested to evaluate the parasitism, in different evaluation times. Substrate types and ideal number of plants were also evaluated. Once A. thaliana hosts M. paranaensis and showed to be a susceptible and reliable tool for studies with this nematode, the methodology optimization conditions were tested by the screening of 29 ecotypes, and variation on susceptibility among these genotypes was observed, indicating the adequacy of the methodology suggested and genetic variability to this trait. The optimization of the experimental conditions using A. thaliana here reported can provide a range of research lines to reach data faster, besides the possibility of increasing the knowledge of plant-M. paranaensis interactions.

Root-knot nematodes are obligate parasites, so changes at their feeding sites can limit their development. Alterations to feeding sites is one of the main actions taken by antagonistic plants. The aim of this study was to assess the response and histopathology of interactions between Meloidogyne javanica and the roots of Macrotyloma axillare cv. Java. The penetration and development of the nematode was assessed from 8 to 30 days after inoculation (DAI) with 3000 eggs + second-stage juveniles (J2) of M. javanica. The reproduction factor (RF) was assessed at 60 DAI, with two inoculation levels, 700 and 1000 eggs + J2, and the changes in the development and histopathology of M. javanica was assessed at 10, 15 and 30 DAI. Suscetible soybean was used as a control. The development of nematodes at the third (J3) and fourth juvenile (J4) stages was delay, despite the presence of J2 inside the roots, and no adult females were found in the M. axillare cv. Java roots. RF was 0.31 and 0.39 for M. axillare cv. Java and 3.40 and 4.52 for soybean at inoculation levels of 700 and 1000 eggs + J2, respectively. The feed cells in M. axillare cv. Java could not effectively nourish the nematode, which led to deformed females 30 DAI. The feed cells and nematode development, however, were normal in soybean. M. axillare cv. Java was resistant to M. javanica and had an antagonistic potential, because it did not prevent the nematode from penetrating the roots but had a negative effect on M. javanica due to the inefficiency of the feeding site.

Summary One of the concerns for nematological research is the absence of information on standard nematode population densities to be used when screening to assess resistance/susceptibility levels of a genotype. In addition, the length of the growth period, especially for perennial crops such as coffee, must also be known. The objective of this work was to evaluate the ideal evaluation periods and population densities of the root-knot nematode, Meloidogyne incognita, for phenotyping Coffea arabica genotypes. Seedlings of coffee ‘Mundo Novo’ with five leaf pairs cropped in 700 cm3 plastic pots were inoculated with population densities of 700, 1400, 2800, 5600 and 11 200 eggs of M. incognita per plant and evaluated at 90, 120, 150 and 180 days after inoculation (DAI) to determine the nematode reproduction factor (RF). The use of population densities of M. incognita from 700-2000 nematodes with evaluations between 90 and 180 DAI was the most suitable to obtain higher RF values and allows earlier and more accurate evaluations, which reduces the time for phenotyping in genetic screening programmes.

Meloidogyne species are widely distributed in coffee growing areas in Brazil, where M. paranaensis is responsible to significant losses to the crop. One of the main management strategies is the use of resistant cultivars, such as Apoatã rootstock and cultivars IPR 100 and IPR 106. However, the parasitic relationship between coffee and M. paranaensis in cultivars carrying resistance genes has been poorly understood. The objective of this paper was to characterize the resistance response of Coffea arabica cv. IPR 106 to M. paranaensis. For this, penetration and histopathological studies were carried out using root tissues parasitized by the nematode. ‘IPR 106’ and ‘Mundo Novo’ (susceptible cultivar) seedlings were inoculated with 4,000 eggs of M. paranaensis and, 15 days after inoculation (DAI), roots were stained with fuchsine to verify the penetration rates of the nematode. Histopathological studies were conducted at 15, 30, 45 and 60 DAI and nematode reproduction was calculated at 120 DAI. ‘IPR 106’ did not avoid completely nematode penetration at 15 DAI, although the number of nematodes was 50 % lower than in Mundo Novo, disregarding the hypothesis of a pre-infectional mechanism of resistance that could prevent nematode penetration completely. However, giant cells and collapsed nematodes were observed in ‘IPR 106’ at 30 DAI, suggesting that the resistance mechanism to M. paranaensis in ‘IPR 106’ involves a post-infectional response and could be mediated by a hypersensitive reaction.

The analysis of nematode communities allows inferring consequences of management practices on the soil food web. We studied the taxonomic structure of nematode communities in preserved areas of the Atlantic forest (native forest = NF) in Ponta Grossa, Paraná State, Brazil, and in three different agroecosystems in neighboring areas to assess the effect of agricultural land use on nematode assemblages. Agroecosystems were located in a red latosol cropped during 30 years under conventional tillage (CT), no-tillage (NT), and minimal tillage (MT). We collected ten composite soil samples in each area in the summer. Nematodes were extracted by Baermann funnel and fixed with formalin. Subsequently, individuals were classified into taxonomic groups and counted on a Peters slide to determine densities of each taxon. Plant-parasitic and free-living nematodes were classified at the genus level. Data were analyzed with the parameters abundance, Bray & Curtis, Shannon-Weaver, and Simpson indexes. We recorded 35 genera and abundance of nematodes in MT and NT areas was more similar. Higher richness was observed in NF in relation to cropped areas, especially under NT and CT. The PCA and clustering analyses from both nematode communities and soil chemical characteristics showed that MT and CT were more similar and NT was clustered near NF. The replacement of native vegetation by cropping systems caused a reduction of nematode diversity, demonstrating the influence of agricultural practices on nematode communities.

Root-knot nematodes cause damage to several crops and the importance of each species can vary according with the crop and the agricultural region. In Brazil, Meloidogyne javanica is one of the most important nematode species parasitizing mulberry. To define management strategies, it is important to know if the crop species is damaged by the parasitism of the nematode and the best choices for control, as the use of nematicides. Biological nematicides have been extensively used in Brazil, but no information regarding its efficiency to control M. javanica in mulberry is available. Besides, it is not known if biological nematicides could improve the quality of leaves or if they alter the nutrient composition of leaves, which could interfere in the development of the silkworms that are feed with these leaves or in the quality of the silk produced. With the aim to address these questions, we propose a study that will start in the phenotyping of the main Brazilian mulberry cultivars to Meloidogyne species, passing through the test of efficiency of biological nematicides in the control of M. javanica in mulberry cultivar Miura, evaluation of the amount and quality of leaves produced and, using these leaves to feed silkworms, in the analyzes of the impact of these diet in the health of silkworms, and in the production and quality of the silk.

The potential of silicon (Si) to control nematodes is often reported in association with the resistance induction mechanism. The objective of this work was to evaluate the hypothesis of resistance induction in plants against nematodes through the application of Si. In vitro experiments were carried out to evaluate the effect of Si and potassium chloride (KCl) on the hatching and mortality of Meloidogyne paranaensis juveniles. For the purpose of a greenhouse experiment, tomato plants were used as a model for bifurcated roots, using the respective control treatments, KCl and distilled water. Ten days after treatment, 2,000 eggs of M. paranaensis were inoculated. At 55 days post-inoculation, the reproduction factor and number of nematodes per gram of root were evaluated. Additionally, the tissue nutrient concentration and gas exchange variables were analyzed. Silicon reduces nematode viability, when in direct contact with the nematode in in vitro experiments and in bifurcated plants. When plants were treated with Si on one side of the root, no nematode control was observed on the opposite corresponding side. Results suggested that Si has a positive effect on the reduction of M. paranaensis population, but probably induced resistance to nematode only through direct action.

Cultivar IPR 106 resulted from a spontaneous hybridization between “Icatu IAC 925” and an unknow dwarf plant. It is a dwarf cultivar with high rusticity, late ripening cycle, large grains, excellent cup quality and resistance to some populations of the nematodes Meloidogyne paranaensis and M. incognita found in the state of Paraná.

Coffee plants are considerably affected by the presence of Meloidogyne spp. and management is based in the use of resistant rootstocks. Systemic induced resistance could constitute an option to manage Meloidogyne paranaensis in coffee-growing areas. Coffee seedlings cv. Mundo Novo were treated with silicate before the inoculation of M. paranaensis to evaluate the potential control of this pathogen. We found, 120 days after the inoculation of 2000 eggs, that the application of silicate was effective to reduce the nematode population, based on reproduction factor and number of nematodes per g roots. Based on the present results, we suggest that the application of silicon constitutes an important alternative for the management of M. paranaensis in infested coffee-growing areas. Further studies are necessary to clarify the biochemical and molecular relationships between M. paranaensis and coffee in the presence of silicon.

Pratylenchus brachyurus has become one of the most serious problems in Brazilian soybean fields. The use of resistant cultivars has long been considered the most practical and effective means of controling nematodes. Nonetheless, to our knowledge, there is no study on the genetic parameters associated with resistance of soybean to P. brachyurus in Brazil. This study was undertaken to estimate resistance genetic parameters under glasshouse conditions. In both trials, we found high phenotypic and genotypic variability, either for reproductive factor or number of nematodes per fresh gram of roots. Furthermore, high coefficients of genotypic determination and variation index were obtained. These results suggest that breeding for this feature can be relatively easy. The next logical step will be to conduct inheritance genetic studies.

The Brazilian Cerrado Region has many natural resources that have high social economic interest. Pequi (Caryocar brasiliense Camb.), a native species from that area, has an edible fruit, which is highly appreciated by the local population, and also a high-quality wood. In January 2010, pequi root samples were collected near the municipality of Rio Verde, Goiás State, Brazil (17°49′25.76″S, 51°02′10.06″W). Roots were washed with tapwater, dried on absorbent paper, cut in 1-cm2 pieces, and processed for nematode extraction by the blender centrifugal flotation method (2). The specimens were identified by morphological and morphometrical characteristics of six adult females mounted in formaldehyde temporary slides (1). Morphological characters used for identification included female body, stylet, pharyngeal overlapping, pharynges, postvulval uterine sac, tail lengths, stylet knobs, number of labial rings, vulva position in relation to body length, body diameters (high body, vulval, and anus region), and the de Man's ratios (a, b, b', c, and c'). Characters measured were consistent with those described for Pratylenchus zeae Graham, 1951 (1); the labial region showed three annuli, stylet was 14.83 (±0.93) μm long, with broad, anteriorly flattened basal knobs. Vulva position was 71.66% (±0.98) of body length and spermatheca was round, small, and without sperm (males were not found). Postvulval uterine sac was short (31.3 ± 4.03 μm) and tail (26.6 ± 3.61 μm) was conoid, pointed, and unstriated. Pharyngeal overlapping length was 30.5 (±6.5) μm; pharynges were 150.83 (± 28.16) μm long. The de Man's ratios obtained were: a = 24.26 ± 2.31; b = 3.89 ± 0.69; b' = 3.08 ± 0.48; c = 17.17 ± 1.47; and c' = 2.25 ± 0.19. To our knowledge, this is the first report of P. zeae infecting pequi. It is difficult to determine the economic importance of this nematode parasite to pequi production since pequi is not yet a commercial crop in Brazil. This finding, however, has long term importance because researchers have been developing improved cultivars by combining favorable agronomic characteristics with high oilseed content for biofuel production. If these are commercialized, P. zeae could become an important pathogen in pequi plantings. References: (1) P. Castillo and N. Vovlas. Pratylenchus (Nematoda: Pratylenchidae): Diagnosis, Biology, Pathogenicity and Management. Koninklijke Brill NV, Leiden, the Netherlands, 2007. (2) W. A. Coolen and C. J. D'Herde. A Method for the Quantiative Extraction of Nematodes from Plant Tissue. State Agric. Entomol. Res. Stn. Ghent, Belgium, 1972.

Teak (Tectona grandis Linn. F.) is one of the most important forest crops in Brazil, occupying areas in different regions, such as Goiás, Mato Grosso, Paraná, and São Paulo states. Teak wood is used for many purposes such as shipbuilding, rolling and plywood, firewood, and charcoal. In May 2011, teak symptomatic feeder root samples, exhibiting inconspicuous, small galls, were collected in the municipality of Piracicaba, São Paulo State, Brazil (22°41′46.90″S, 47°38′36.84″W). Specimens were identified through perineal patterns and esterase phenotypes of 20 adult females (1,2). Perineal patterns and esterase phenotypes were consistent with those described for Meloidogyne arenaria (Neal, 1889) Chitwood, 1949 and M. javanica (Treub, 1885) Chitwood, 1949. Perineal patterns of M. arenaria showed a low dorsal arch, compressed dorsolaterally, with lateral field marked by some forked and broken striae; no punctate markings between anus and tail terminus were observed. Perineal patterns of M. javanica were rounded, with low dorsal arch, striae smooth, lateral field distinct, clearly demarcated from striae by parallel lines. From the esterase electrophoresis we obtained A2 (Rm:1.2;1.3) and J3 (Rm:1.0;1.25;1.4) phenotypes, typical from M. arenaria and M. javanica, respectively. To our knowledge, this is the first report of M. arenaria parasitizing teak roots in Brazil and elsewhere (new host) and the first report of M. javanica infecting teak in the State of São Paulo. Previously, M. javanica was reported to be infecting teak-growing areas in the State of Mato Grosso (3). This finding has a great importance, not only by the inclusion of these parasites in teak pathological scenario, but also for predicting possible damage in plant species used in teak-based intercropping systems. References: (1) P. R. Esbenshade and A. C. Triantaphyllou. J. Nematol. 22:10, 1990. (2) K. M. Hartman and J. N. Sasser. 1985. Page 115 in: An Advanced Treatise on Meloidogyne. Volume II, Methodology. K. R. Barker et al., eds. North Carolina State University Graphics, Raleigh,1985. (3) R. A. Silva et al. Nematol. Bras. 27:261, 2003.

Common bean (Phaseolus vulgaris F.) is one of the most important crops in Paraná State, which is responsible for almost 10% of the Brazilian production (4). Root knot nematodes, Meloidogyne spp., are common parasites of this crop worldwide, but damage caused by Meloidogyne inornata has not been reported. During a survey of nematode species present on common bean fields in Paraná State, Brazil, galled root samples of cultivars Tuiuiú and Eldorado were submitted, in June 2012, in the Nematology Laboratory from IAPAR, collected in the municipalities of Araucária (25°35′34″S, 49°24′36″W) and Santana do Itararé (23°45′18″S, 49°37′44″W). Plants did not exhibit any above-ground symptoms. The specimens were identified through perineal patterns and esterase phenotypes of 20 adult females extracted from dissected roots (2,3). The population densities observed in the samples were 140 and 700 J2 and eggs per gram of roots, respectively, for both samples. Characteristics were consistent with those described for M. inornata. For example, perineal patterns of M. inornata showed a high dorsal arch, with smooth to wavy striae, similar to those of M. incognita; but no punctate markings between anus and tail terminus were observed. However, from the esterase electrophoresis we obtained the I3 (Rm = 0.83, 1.15, and 1.32) phenotype, typical of M. inornata, a species-specific phenotype used to differentiate this species from M. incognita (1). Moreover, the excretory pore of adult females was located 32.1 (± 5.4) μm from the anterior end, consistent with the M. inornata description (25 to 53 μm) (1). To the best of our knowledge, this is the first report of M. inornata parasitizing common bean roots. This finding has great importance for Brazilian agriculture, since this nematode may damage common bean plants and become an additional problem for this crop. Additional work is necessary in order to elucidate the losses caused by M. inornata on common bean. References: (1) R. M. D. G. Carneiro et al. Nematology 10:123, 2008. (2) P. R. Esbenshade and A. C. Triantaphyllou J. Nematol. 22:10, 1990. (3) K. M. Hartman and J. N. Sasser. Page 115 in: An Advanced Treatise on Meloidogyne, Volume II Methodology. K. R. Barker et al., eds. Raleigh: North Carolina State University Graphics, 1985. (4) MAPA. Feijão, Ministério da Agricultura, Brasil. Retrieved from http://www.agricultura.gov.br/vegetal/culturas/feijao September 05, 2012.

Nematode diseases have a worldwide importance for several economic agricultural crops, such as soybean. Frequently, new or secondary pathogens arise as emergent diseases due to the intensified use of agricultural lands, causing extensive yield losses. Helicotylenchus dihystera (Hd) and Scutellonema brachyurus (Sb) appear as potential pathogens for soybean in Brazil, since their spread and population densities have been increased on soybean growing areas. Aiming to evaluate the quantitative distribution of Hd and Sb in soybean fields in South Brazil, a survey was conducted during the growing seasons of 2014–2015 and 2015–2016 in which 1,088 soil samples and 1,043 root samples were analyzed. Besides, two greenhouse experiments were conducted to evaluate the pathogenicity of both nematodes to soybean plants, in comparison with P. brachyurus (Pb), a known pathogen of the crop. The survey demonstrated that Pb, Hd and Sb are widely distributed in the States of Parana, Santa Catarina and Mato Grosso do Sul. Besides, we proved that Hd and Sb multiply and cause root lesions in soybean cv. Potencia, since they were found inside roots, and can be considered as potential pathogens for soybean plants.

Our study surveyed Meloidogyne spp. from tobacco cultivars in Brazil carrying the Rk gene, which confers resistance to Meloidogyne incognita races 1 and 3. Identification of Meloidogyne populations from 39 tobacco fields was based on the analysis of esterase phenotypes, perineal patterns, and 18S-internal transcribed spacer (ITS)1-5.8S ribosomal RNA sequences. Biometric characterization and differential host tests of isolates were determined as well. We detected M. incognita, M. javanica, M. enterolobii, M. arenaria, and M. inornata in 18 (46.2%), 16 (41%), 10 (25.6%), 2 (5.1%), and 1 (2.6%) samples, respectively. Mixtures of species were found in 25.6% of the samples. This is the first report of M. inornata parasitizing tobacco in Brazil’s southern region. Two morphological and biochemically unusual populations had host ranges and ITS1 sequences nearly identical to M. enterolobii and M. incognita, respectively. Pathogenic and biometric intraspecific variations were observed. Based on our results and considering the limited efficiency of the Rk gene, it is indispensable not only to search for resistance sources to M. incognita virulent strains but also to consider resistance to M. enterolobii, M. inornata, M. arenaria, and M. javanica in tobacco breeding programs. Changes in integrated management procedures should be considered to avoid increased crop damage in the future.

International audience; 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 compat‐ible 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 re‐production 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 environ‐ments account for the broad host spectrum and wide geographical distribution of M. incognita and thus to its economic impact. pact. This surprising adaptability without sex poses both evolutionary and agro‐economic challenges.

The objective of this study was to accomplish a survey on populations of Meloidogyne and Pratylenchus species in sugarcane farming areas in the state of Alagoas, Brazil. Twenty samples of soil and roots were processed to extract and quantify nematodes; however, the identification of Meloidogyne species was performed using only 12 samples. Pratylenchus spp. were reported at moderate population levels of 68-1556 specimens 50g-1 of roots and 2-298 specimens 100cm-3 of soil in twenty analyzed samples. For Meloidogyne spp., these values were of 12-487 specimens 50g-1 of roots and 0-140 specimens 100cm-3 of soil. Based on electrophoresis of esterase isozymes, M. incognita was reported to be the most frequent species, followed by M. javanica and M. arenaria. Pratylenchus species identified through morphometrical and morphological characteristics were P. zeae and P. brachyurus , with predominance for the first species. No significant correlation (P≤0.05) were reported between nematode populations and sugarcane cropping systems. RESUMO: O objetivo deste trabalho foi realizar um levantamento de espécies de Meloidogyne e de Pratylenchus existentes em áreas de cultivo de cana-de-açúcar, no estado de Alagoas. Vinte amostras de solo e raízes foram processadas para a extração e quantificação, sendo a identificação das espécies de Meloidogyne realizada em 12 amostras. Detectou-se a presença de Pratylenchus spp. em níveis populacionais médios de 68-1556 espécimes 50g-1 de raízes e 2-298 100cm-3 de solo, em todas as amostras. Para Meloidogyne spp., esses valores foram de 12-487 50g-1 de raízes e 0-140 100cm-3 de solo. Com base na eletroforese da isoenzima esterase, M. incognita foi a espécie mais frequente, seguida por M. javanica e M. arenaria . As espécies de Pratylenchus identificadas pelas características morfológicas e morfométricas, foram P. zeae e P. brachyurus , com predomínio da primeira espécie. Não houve correlações significativas (P≤0,05) entre as populações de nematoides e as características dos sistemas de cultivo de cana-de-açúcar.

Bean crops have their productivity limited by biotic factors, as the phytonematodes. Several species have been reported causing damage to the crop, especially those from the Meloidogyne genus. Recently, a new species was reported parasitizing bean plants in Parana State, Brazil, Meloidogyne inornata. The present work was aimed in order to study the pathosystem bean and M. inornata, through the evaluation of host reaction of 32 bean cultivars to the nematode, the potential damage of this pathogen to the crop, and the biology and parasitism of M. inornata on bean, under different temperatures, comparing with M. incognita. The host reaction was accessed under greenhouse conditions, with an initial population density of 2000 eggs of each nematode species per plant. Fifty days after inoculation, it was found that all tested cultivars were susceptible to M. inornata, however with varying extent. Pathogenicity of M. inornata on bean cv. Tuiuiu was also evaluated under greenhouse conditions, with the following initial population densities: 0 (check); 0.0625; 0.125; 0.25; 0.5; 1; 2; 4; 16; 32; and 64 eggs per cm3 of soil. Tolerance limit obtained to this cultivar was 9.9 nematodes per cm3. In relation to the comparative biology between M. inornata and M. incognita, under growth chamber and three different temperatures, 18, 25 and 32°C, results showed that under 18°C, both species have their life cycles retarded, while under 32°C, the cycle is accelerated.

Root-knot nematodes, especially Meloidogyne incognita, are recognized by expressive damages on important agronomic crops worldwide. White oat (Avena sativa) is an excellent alternative to sustainable management of nematodes especially when used in crop rotation with another plant species. In this context, the aim of the present work was to study the resistance of IPR Afrodite oat cultivar to M. incognita, using histopathological methods in a comparative approach with the susceptible cultivar URSFAPA Slava. Experiments were done under greenhouse conditions, with 6 replicates for each cultivar and evaluation time. Observations of fuchsin-stained roots at 3, 9, 15 and 30 days after inoculation (DAI) revealed that the resistant cultivar did not suppress nematode penetration but caused a delay in the nematode development compared with the susceptible cultivar. Moreover, mature, egg-laying females were not found in the roots of the resistant cultivar. Hypersensitive reaction (HR) was observed at 18 DAI. The HR was characterized by the formation of few giant cells of reduced size on the resistant cultivar, associated with collapsed M. incognita specimens. In most specimens, light blue fluorescence indicated lignified cells, an active plant response to nematode penetration or establishment. Intercellular spaces were of dark yellow color, indicating the presence of phenols, often associated with plant defense mechanisms to nematodes and other pathogens. Our results suggest that resistance of IPR Afrodite to M. incognita is mediated by a HR response and studies are needed to clarify the nature of compounds produced by the plant involved in the resistance.

Summary Common bean diseased plants with symptoms of decline and root knots were collected in two growing areas in the municipality of Araucária, Paraná State (Brazil). Morphological (perineal patterns), biochemical (esterase phenotypes) and molecular (ITS1 sequences) studies allowed us to identify the infecting nematode as Meloidogyne luci. To our knowledge, this is the first formal record of M. luci parasitizing common bean in Paraná State, Brazil.

The aim of this study was to assess the susceptibility of rice genotypes toPratylenchus brachyurusand investigate the inheritance of resistance in the crop. Two experiments were conducted under controlled conditions, using naturally infested soil. Twenty-six rice genotypes were assessed, with maize used to show the susceptibility pattern. The maize was cultivated for 90 days and the initial nematode population was determined. Then, rice genotypes were cultivated, and the final nematode population and the reproduction factor (RF) were estimated 90 days after germination. All genotypes were susceptible toP. brachyurusin the two experiments but only one showed statistical differences, indicating variation in susceptibility, and genotypes Linhagem L03-107 and Cateto Amarelo scored higher than the control genotype, with RF of 8.80 and 9.48, respectively. Inheritance of resistance was poorly influenced by genotype genetics. Cluster analysis allowed the identification of five different groups of genotypes but there was low genetic variability among the genotypes.

Coffee crop is of high importance to the Brazilian agriculture, but plant-parasitic nematodes, especially the root-knot nematode Meloidogyne paranaensis, can reduce the productivities of coffee plants. The management of nematodes in coffee is done mainly with the use of resistant plants and chemical and biological nematicides, mainly in large-scale farms. Nevertheless, there is scarce information about the efficacy of available nematicides and new molecules in the control of root-knot nematodes in coffee. Thus, the objective of the present work was to evaluate the efficacy, under greenhouse conditions, of four chemical (cadusafos, carbofuran, fluopyram, and fluensulfone) and two biological (Purpureocillium lilacinum and Trichoderma harzianum) nematicides and one organo-mineral compost in the control of M. paranaensis, the main nematode species for Parana coffee production. For this, coffee plants of the cultivar Mundo Novo with four to five pairs of leaves were transplanted to 3.6 L-capacity plastic pots and inoculated with 1,000 eggs of M. paranaensis; noninoculated plants were used as control. Nematicide treatments at the recommended dosages by manufacturers were done soon after the transplant and inoculation or 60 days after. Evaluations were done 120 days after the inoculation on the basis of nematode reproduction factor (RF) and number of nematodes per gram of root (Nema/g). Additionally, the development of plants was measured by the variables plant height, fresh top weight, and fresh root weight. The results showed that the best nematicides to reduce nematode population were fluensulfone and fluopyram, with 99% and 100% reduction of the nematode RF, respectively. Carbofuran and cadusafos, although controlled the nematode, caused phytotoxicity to coffee plants. Biological nematicides were not effective in the reduction of the nematode population, but the application of P. lilacinum provided better development of plants. These results have high relevance, as they demonstrated the effect of chemical molecules and biological agents, both in M. paranaensis-infected plants and in noninfected plants; with this information, growers can choose products with a higher nematicidal effect and that allow better plant development for use in infested fields.

A greenhouse study using naturally infested soil was conducted to evaluate the susceptibility of rice genotypes to Pratylenchus zeae and the broad-sense heritability of host resistance. Twenty-six rice genotypes were evaluated and maize ‘BRAS 3010’ and pearl millet ‘AMN 17’ were used as susceptible checks. Two variables, initial and final population densities and reproduction factor of P. zeae, were measured before sowing and 90 days after seed germination. The genotypes varied significantly in susceptibility to P. zeae. Heritability levels as high as 77.2 and 68 % for the reproduction factor and the number of nematodes per gram of roots, respectively, suggested that breeding rice for P. zeae resistance is difficult due to large environmental effects on the phenotypic expression of resistance.

In Brazil, Pratylenchus brachyurus damages economic important crops and it is managed with non-chemical methods such as crop rotation or resistant cultivars. However, the variability in reproduction and damaging effects observed among P. brachyurus populations could limit the efficacy and long lasting effect of nematode control practices. Twelve populations of P. brachyurus from different geographical areas of Brazil were analyzed morphologically and molecularly. The morphological and morphometric characters of the populations studied were variable, but fitted those of P. brachyurus. Assemblages of populations with different host preferences and reproductive capabilities were revealed by PCA of these populations using selected morphological characters. Phylogenetic analysis using ITS-rDNA sequences distinguished statistically supported groups of sequences that matched those of other populations of P. brachyurus deposited in the GenBank, confirming the identity of populations here studied. Intraspecific sequence diversity was observed among the populations. These variant sequences suggest the presence of microheterogeneity between ITS-1 copies in individuals. The findings of this study did not provide evidence of cryptic species in the P. brachyurus populations studied. The variability within and among populations of P. brachyurus observed in this work must be taken into consideration in breeding programs for resistance to this nematode.

In Brazil, oat (Avena sativa) is widely cultivated as a winter crop mainly in the south region. However, there are several species of nematodes that are of economic importance to oats and knowledge about the reaction of cultivars to root-knot and root-lesion nematodes is sparse. Thereby, in this present work we aimed to characterize the host response of some selected oat genotypes to Meloidogyne incognita (Mi) race 3, M. javanica (Mj), M. paranaensis (Mp), M. enterolobii (Me), and P. brachyurus (Pb) under greenhouse conditions, based on the nematode reproductive factor (RF) and number of nematodes per gram of roots [nem (g root)−1]. We also determined the variance components associated with root-knot and root-lesion resistance. Results revealed variation in the susceptibility of cultivars to nematodes tested, except for M. enterolobii, in which all cultivars tested were highly resistant. The cultivar IPR Afrodite was the most resistant to root knot species (Mi race 3, Mj, Mp and Me), whereas all cultivars tested were considered susceptible to Pb. Data of nem (g root)−1 confirmed the characterization of the cultivars based on RF values.

Five pot trials were carried out under glasshouse conditions to assess the host response of some selected rice cultivars to Meloidogyne javanica, M. paranaensis and M. enterolobii, based on nematode reproductive factor (RF) and number of nematodes (g root)−1. We also determined the broad-sense heritability and variance component estimations associated with M. paranaensis and M. incognita resistance. In addition, cluster analysis of cultivars was conducted. All cultivars were rated as susceptible or highly susceptible to M. javanica and highly resistant to M. enterolobii. To M. paranaensis, only cvs IAPAR 177 and BRS Caravela were resistant. From the principal component analysis and Ward’s cluster analysis, we obtained four conspicuous clusters of cultivars according to Meloidogyne species resistance, which demonstrates the variability of the genetic material studied. Higher broad-sense heritability values for RF and nematodes (g root)−1 were obtained. Taken together, our findings suggest that improvement of resistance of rice to Meloidogyne species resistance is possible. The implications for management programmes are also discussed.

The oat cultivar IPR Afrodite, resulting from a cross between CFT 2 and the inbred line ER 88144-1, is high-yielding, has grain quality traits that are relevant for food processing and industry, and is resistant to the root-knot nematode species Meloidogyne incognita, M. javanica, M. paranaensis and M. enterolobii.

Abstract Nowadays, rice is among the most preferred crops for rotation with soybean and cotton in the large producing areas of Central Brazil. Nevertheless, the host status of the Brazilian upland rice cultivars for Meloidogyne incognita race 4 and Rotylenchulus reniformis has not been investigated and remains unknown. This study dealt with the assessment of the host response of some selected Brazilian upland rice cultivars to these nematodes under glasshouse conditions. The host status for each tested interaction was based on the nematode reproduction factor (RF) and number of nematodes (g root)–1. Two experiments with M. incognita race 4, referred to as trial 1 (initial population (IP) = 4000) and trial 2 (IP = 800), included, respectively, 14 cultivars (cvs AN Cirad 141, BRS Monarca, BRS Primavera, AN Cambará, BRS Pepita, BRS Curinga, BRS Sertaneja, IAPAR 9, IAPAR 62, IAPAR 63, IAPAR 64, IAPAR 117, IAC 201, IAC 202) and 19 cultivars (the same ones in Experiment 1 plus cvs BRS Maravilha, BRS Talento, BRS Bonança, Ricetec Ecco, BRS Soberana). Except for cv. BRS Pepita, rated as resistant, the cultivars were rated as susceptible or moderately susceptible (RF means ranged from 1.09 to 12.56). In a third experiment with R. reniformis (IP = 1800) that included the same cultivars as in Experiment 1, all cultivars were rated as resistant (RF means ranged from 0.01 to 0.29).

Abstract Due to the complexity of management of plant-parasitic nematodes in cash crops, the use of non-chemical methods, such as rotation with green manures, has increased in recent years. However, data about the host status of green manures for lesion nematodes are scarce. Thus, two glasshouse trials were carried out to evaluate the host status of some green manures for two isolates of Pratylenchus brachyurus, a root-lesion nematode often found attacking soybean, maize and cotton in Brazil. Green manures tested were pigeon pea (Cajanus cajan) cultivars Fava Larga and Iapar 43, Crotalaria juncea, C. spectabilis, C. mucronata, C. breviflora, C. ochroleuca, C. paulina, velvetbean (Mucuna pruriens) cvs Black, Dwarf and Gray. Soybean cv. Pintado and French marigold (Tagetes patula) were included as standard good and poor hosts for P. brachyurus. In a separate glasshouse experiment, a naturally infested soil was used to evaluate the suitability of two green manures to P. brachyurus in comparison with two gramineaceous cover crops. In addition, morphometric studies were carried out with the two isolates of P. brachyurus used in experiments in order to confirm the species. Among the 11 green manures tested, at least two, C. spectabilis and C. breviflora, can be useful as rotation crops to reduce population densities of P. brachyurus, irrespective of the origin of the nematode. By contrast, all velvetbean cultivars and C. juncea must be avoided in infested areas as they are good hosts for the nematode.

Pratylenchus brachyurus é um dos nematóides mais disseminados na cultura do algodão nas áreas produtoras do Brasil. Sua patogenicidade ao algodoeiro, entretanto, é pouco estudada. Os objetivos deste trabalho foram: i) correlacionar níveis populacionais iniciais crescentes de P. brachyurus (0, 12.000, 30.000 e 75.000 exemplares/ planta) com os danos causados ao algodoeiro \'Delta Opal\'; ii) avaliar a patogenicidade de populações de P. brachyurus em algodoeiros \'Delta Opal\' e \'Fibermax 966\'; iii) testar cultivares de algodão em relação à reprodução de três populações de P. brachyurus ; iv) caracterizar a relação parasito-hospedeiro (em termos de suscetibilidade/resistência) de alguns adubos verdes, coberturas vegetais e pastagens a Pratylenchus brachyurus; v) caracterizar molecularmente populações de P. brachyurus, através de PCR-RFLP e seqüenciamento da região ITS-1 do rDNA. Os resultados sugerem que P. brachyurus é patógeno pouco agressivo da cultura do algodão, já que não se verificaram danos significativos às plantas em densidades populacionais do nematóide inferiores a 12.000 exemplares/ planta. Em relação às cultivares, todas foram suscetíveis a P. brachyurus . Entre as espécies vegetais testadas, as que se mostraram resistentes a P. brachyurus foram Crotalaria spectabilis, C. breviflora, amaranto \'BRS Alegria\', nabo forrageiro \'Comum\' e as cultivares de aveia preta Campeira Mor, IPFA 99006, Comum, CPAO 0010 e Garoa. As análises de PCRRFLP revelaram variabilidade genética entre as diferentes populações de P. brachyurus estudadas, em função dos diferentes padrões de bandas encontrados para as populações estudadas. O seqüenciamento da região ITS-1 do rDNA confirmou a variabilidade observada pela digestão enzimática, além de evidenciar heterogeneidade das regiões 18S e ITS-1 do rDNA de P. brachyurus Although Pratylenchus brachyurus is widespread in Brazilian cotton fields, information about its importance as a cotton pathogen is scarce. The objectives of this work were: i) correlate crescent initial population densities (0; 12,000; 30,000; and 75,000 nematodes/ plant) with damage on cotton \'Delta Opal\'; ii) measure the pathogenic effect of P. brachyurus on cotton \'Delta Opal\' and \'Fibermax 966\'; iii) characterize the reaction of cotton cultivars to three populations of P. brachyurus ; iv) characterize the host reaction (in terms of susceptibility/ resistance) of some green manures, cover crops and pastures to two populations of P. brachyurus; v) characterize different populations of P. brachyurus by PCR-RFLP and sequencing of ITS-1 rDNA region. Results suggest that P. brachyurus is an eventual pathogen of cotton, since high population levels were necessary to reduce plant growth (< 12,000 nematodes/ plant). All cotton cultivars tested were rated as susceptible to P. brachyurus In relation to crop species tested, Crotalaria spectabilis, C. breviflora, amaranth \'BRS Alegria\', oil radish \'Comum\', and the black oat cultivars Campeira Mor, IPFA 99006, Comum, CPAO 0010, and Garoa were resistant to P. brachyurus PCR-RFLP showed intraspecific variability for different population of P. brachyurus studied. Sequencing of the ITS-1 rDNA region confirmed the results of the enzymatic digestion and demonstrated heterogeneity of 18S and ITS-1 rDNA regions of P. brachyurus.