RESUMO
Weeds can be hosts of root-knot nematodes of the genus Meloidogyne. The importance of the species Meloidogyne morocciensis parasitizing many crops is recognized, but their reproductive capacity in weeds is not known. The present study hypothesizes the ability of M. morocciensis to parasitize and reproduce in different weed species found in Brazil. The objective was to evaluate the reproduction of M. morocciensis in 36 weed species. The plants were individually inoculated with 5,000 eggs and second stage juveniles and kept in greenhouse for 60 days. The experimental design was completely randomized with twelve replications. The root system of each plant was evaluated for gall index (GI), final nematode population (PF), number of nematode/g of root (NNGR) and reproduction factor (RF). It was verified that M. morocciensis has the capacity to parasite 36 weed species belonging to 16 different botanical families, confirming the hypothesis proposed. From the 36 species evaluated, 77.8% (28) were susceptible (FR ≥ 1.0) to M. morocciensis. The present study is the first to identify different weeds as hosts of M. morocciensis, evidencing its polyphagous habit, indicating species of plants with high capacity to multiply this nematode and that need more attention during the integrated management of these pathogen.
Assuntos
Tylenchida , Tylenchoidea , Humanos , Animais , Brasil , Plantas Daninhas , ReproduçãoRESUMO
BACKGROUND: While searching for novel small molecules for new organic pesticide agents against plant-parasitic nematodes, we found that the hexane extract from the roots of Senecio sinuatos and its main secondary metabolite, 3ß-angeloyloxy-6ß-hydroxyfuranoeremophil-1(10)-ene (1), possess nematicidal activity against the second stage juvenile (J2) of Meloidogyne incognita and Nacobbus aberrans. Both species reduce yield of various vegetable crops. These results encouraged us to synthesize esters 3-9 formed by diol 2, obtained by alkaline hydrolysis of 1 and acetic anhydride, benzoic acid, 2-nitrobenzoic acid, 2-bromobenzoic acid, 4-nitrobenzoic acid, 4-bromobenzoic acid, and 4-methoxybenzoic acid, respectively. The nematicidal activity of these esters was evaluated and compared with that of the free benzoic acids. RESULTS: Natural product 1 and derivatives 2-9 were obtained and characterized by their physical and spectroscopic properties, including one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) experiments; X-ray diffraction analysis established their absolute configuration. The nematicidal activity of compounds 1-9 was assessed in vitro against M. incognita and N. aberrans J2 and was compared to activity shown by benzoic acid, 2-nitrobenzoic acid, 2-bromobenzoic acid, 4-nitrobenzoic acid, 4-bromobenzoic acid, and 4-methoxybenzoic acid. The esters suppressed nematodes more than free benzoic acid. Nacobbus aberrans J2 were suppressed, with compounds 5, 6, and 8 being the most active. CONCLUSION: Esters formed by 3ß,6ß-dihydroxyfuranoeremophil-1(10)-ene and ortho- or para-substituted benzoic acids containing electron acceptor groups had nematicidal activity against N. aberrans. These compound can potentially serve as a model for the development of new organic nematicidal agents. © 2022 Society of Chemical Industry.
Assuntos
Tylenchida , Tylenchoidea , Animais , Antinematódeos/química , Benzoatos/farmacologia , Ácido Benzoico , Ésteres , Nitrobenzoatos , Tylenchida/metabolismo , Tylenchoidea/metabolismoRESUMO
Several species of nematodes are known to cause losses to cowpea (Vigna unguiculata) throughout the world. In Brazil, Aphelenchoides besseyi was described as causing damage on soybean, cotton, and common bean, but no report was found about the parasitism of this nematode in cowpea. This study aimed to verify the host reaction of cowpea cultivars to A. besseyi. The experiment was conducted under greenhouse conditions, using two A. besseyi populations as inocula, obtained from symptomatic soybean and cotton plants collected in naturally infested fields. Cultivars Imponente, Aracê, Guariba, Tumucumaque, Nova Era, and Tracuateua were inoculated with 500 A. besseyi of each population, separately, into soil, and after 30 days from the inoculation nematodes were extracted from shoot systems. Both populations were able to parasitize all the cowpea cultivars. Independently of the cultivar, cowpea plants exhibited symptoms of leaf deformation similar to those described for soybean, cotton, and common bean and, in addition, severe brooming was observed, with the interior of the stems being porous and necrotic. To our knowledge, this is the first report of parasitism by A. besseyi of cowpea in Brazil, under greenhouse conditions, increasing the list of hosts of this nematode.
Assuntos
Fabaceae , Nematoides , Tylenchida , Vigna , Animais , Brasil , Glycine maxRESUMO
Sugarcane-associated nematodes (Saccharum spp.) can reduce productivity up to 50%. Through the survey, it was possible to identify the main nematodes that occur in a certain region as a tool for designing the best management and control strategies. The aim of this study was to characterize the population of nematodes associated with sugarcane in the North Central, North Pioneiro and Northwest mesoregion of the state of Paraná, Brazil, quantify the nematode genera associated with the crop and identify the species of Pratylenchus and Meloidogyne. A total amount of 89 soil and root composite samples were collected in nine municipalities. Nematodes were extracted and counted in a Peters counting chamber under an optical light microscope. Morphological description followed identification keys. Pratylenchus spp. were identified by morphological characteristics; Meloidogyne spp. were identified by morphological characteristics and isoenzyme electrophoresis. Twelve genera of nematodes associated with sugarcane were identified: Pratylenchus, Meloidogyne, Helicotylenchus, Xiphinema, Mesocriconema, Trichodorus, Aphelenchus, Hoplolaimus, Tylenchus, Tylenchorhynchus, Ditylenchus, and Paratrichodorus. The genera Pratylenchus and Meloidogyne were found with the highest frequencies in the roots. Among the species of Pratylenchus, P. zeae and P. brachyurus were found, with P. zeae being the most frequent. Among the Meloidogyne species, only M. javanica was found. These results are essential to aid decision making in the management of phytonematodes, mainly in the development of new control strategies and in directing genetic breeding programs for development of sugarcane cultivars for the Paraná state.
Assuntos
Tylenchoidea , Tylenchida , Saccharum/parasitologia , Nematoides/classificaçãoRESUMO
Cereal cyst nematode is a major pest of small grain cereals, which causes huge yield losses to crops in China and other parts of the world. In this study, the effects of five inorganic ion concentrations on egg hatching of Heterodera avenae were studied. Results revealed that ZnCl2 and FeCl3 promoted hatching of induced and natural diapausing eggs. The cumulative hatching rates of eggs were 49 % and 13 % at 30 mM ZnCl2 and 10 mM FeCl3, respectively, which were higher than those of other treatments. The hatching ability promoted by ZnCl2 is greater than by FeCl3. Diapause induced eggs in ZnCl2 continued to hatch after 10 days; however, those in FeCl3 mainly hatched in the first two weeks. ZnCl2 had obvious stimulating effects on the hatching of natural diapause and nondiapause free eggs at 15 and 30 mM concentrations. FeCl3 promoted the hatching of natural diapause eggs; howevr, it inhibited hatching of nondiapause free eggs. Conversely, different concentrations of inorganic ions did not have any stimulatory effect on white female eggs. In the nematode life cycle, hatching is the critical stage because juveniles may be infected. The results of this study provide useful information the use of new fertilizers (including promoted hatching inorganic ions) applied before planting for controlling nematode diseases caused by H. avenae.(AU)
Assuntos
Grão Comestível/parasitologia , Tylenchida/crescimento & desenvolvimento , Cistos/parasitologiaRESUMO
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.
Assuntos
Nematoides , Phaseolus , Tylenchida , Animais , Brasil , Glycine maxRESUMO
Aberrant nematode larval migration in the CNS of horses is rare but frequently fatal; one of the main etiological agents involved in this illness is Halicephalobus gingivalis. This soil nematode has been associated with several fatal equine meningoencephalitis reports worldwide; however, it had never been diagnosed in horses of Mexico. A 10 year-old Andalusian horse presented dysphagia, fever, weakness, prostration and ataxia; the patient expired during the medical attention. Post mortem examination was performed and no gross alterations were found. Histopathology revealed meningoencephalitis, vasculitis and intralesional adult nematodes, larvae and eggs compatible with Halicephalobus spp. A polymerase chain reaction (PCR) for the nuclear large subunit ribosomal RNA gene (LSU rDNA) of nematodes was performed from formalin-fixed and paraffin wax-embedded sections of brain. Posterior nucleotide sequence analysis of the amplified fragment identified the agent as H. gingivalis. To our knowledge, this is the first confirmed report of Halicephalobiasis in Mexico.
Assuntos
Doenças dos Cavalos/diagnóstico , Meningoencefalite/veterinária , Infecções por Rhabditida/veterinária , Rabditídios/isolamento & purificação , Animais , Evolução Fatal , Doenças dos Cavalos/parasitologia , Cavalos , Masculino , Meningoencefalite/diagnóstico , Meningoencefalite/parasitologia , México , Rabditídios/classificação , Infecções por Rhabditida/diagnóstico , Infecções por Rhabditida/parasitologia , Tylenchida/isolamento & purificaçãoRESUMO
RATIONALE: The nematode Aphelenchoides besseyi is the causal agent of green stem and foliar retention, a soybean disease recently described in Brazil. This condition can reduce soybean yield by up to 100%. However, little is known about chemical interactions between the plant and pathogen. Therefore, this work aimed to investigate metabolites from healthy soybean roots and from soybean roots that were inoculated with A. besseyi. METHODS: A. besseyi were multiplied in vitro with Fusarium sp. colonies in Petri dishes for 25 days, and were axenically inoculated into hydroponics healthy soybean plants. The metabolites were extracted from the roots of healthy and A. besseyi-infected plants 16 days post-inoculation. These extracts were analyzed using an untargeted metabolomic method with an ultra-high-performance liquid chromatography/electrospray ionization /tandem mass spectrometry (UHPLC/ESI-MS/MS) and molecular networking approach. RESULTS: Roots from infected plants showed morphological alterations such as shrinkage, darkening, and arching. Similarly, they also showed an increased presence of flavonoids, compared with healthy roots. Compounds such as neobavaisoflavone, glycitin, genistin, and genistein were putatively identified and had greater intensity in inoculated roots. These compounds are linked to the defensive mechanisms in plants against nematodes. Moreover, coumaric acid, also exclusively putatively identified in inoculated roots, shows activity related to inhibition of root growth. CONCLUSIONS: Liquid chromatography, mass spectrometry, and molecular networking approaches proved to be a powerful tool for the metabolomic study of GSFR. This study showed metabolomics differences of protective substances in the roots, evidencing a quick response of the plant to the attack of A. besseyi.
Assuntos
Glycine max/metabolismo , Glycine max/parasitologia , Metabolômica/métodos , Raízes de Plantas/parasitologia , Espectrometria de Massas em Tandem/métodos , Animais , Cromatografia Líquida de Alta Pressão , Interações Hospedeiro-Parasita , Doenças das Plantas/parasitologia , Raízes de Plantas/metabolismo , Metabolismo Secundário , Tylenchida/patogenicidadeRESUMO
Genetically diverse interspecific hybrids of Vitis were selected for resistance to Pratylenchus brachyurus. Three segregating populations with 57 hybrid crosses were evaluated. The parents included Vitis romanetiiC166-043 × 07355-075, 06354-047 × Cereza and 06354-047 × Nocera, selected from the germplasm bank at the University of California, Davis, the United States. The experiment was arranged in a randomized block design, with three replications and three plants per plot. Root mass, nematodes per gram of root and reproduction factor were determined and used as quantitative variables; 16 multi categoric descriptors were also evaluated. The traits were analyzed using the Ward-Modified Location Model procedure (Ward-MLM) for the composition of genotype groups. Genetic parameters and prediction of genetic values by Restricted Maximum Likelihood / Best Linear Unbiased Prediction (REML / BLUP) were assessed. The Ward-MLM classification strategy supported the formation of three homogeneous groups. Group I comprised 13 hybrids; Group II, 26 hybrids; and Group III, 18 hybrids. Groups II and III contained hybrids resistant to P. brachyurus. High broad sense heritability values were found for root mass, reproduction factor and nematodes per gram of root, which provided genetic gain and allowed selection of resistant genotypes available for cloning, since the total genetic variance occurred due to the dominance effects. Of the 57 genotypes assessed, those with the lowest genotypic values for reproduction factor were selected as resistant, including: CH3.2, CH3.23, CH3.8, CH3.37, CH3.38, CH3.41, CH3.36, CH2.1, CH2.7, CH1.1, CH1.3 and CH1.2.
Assuntos
Resistência à Doença/genética , Tylenchida , Vitis/genética , Vitis/parasitologia , Melhoramento VegetalRESUMO
Genetically diverse interspecific hybrids of Vitis were selected for resistance to Pratylenchus brachyurus. Three segregating populations with 57 hybrid crosses were evaluated. The parents included Vitis romanetiiC166-043 × 07355-075, 06354-047 × Cereza and 06354-047 × Nocera, selected from the germplasm bank at the University of California, Davis, the United States. The experiment was arranged in a randomized block design, with three replications and three plants per plot. Root mass, nematodes per gram of root and reproduction factor were determined and used as quantitative variables; 16 multi categoric descriptors were also evaluated. The traits were analyzed using the Ward-Modified Location Model procedure (Ward-MLM) for the composition of genotype groups. Genetic parameters and prediction of genetic values by Restricted Maximum Likelihood / Best Linear Unbiased Prediction (REML / BLUP) were assessed. The Ward-MLM classification strategy supported the formation of three homogeneous groups. Group I comprised 13 hybrids; Group II, 26 hybrids; and Group III, 18 hybrids. Groups II and III contained hybrids resistant to P. brachyurus. High broad sense heritability values were found for root mass, reproduction factor and nematodes per gram of root, which provided genetic gain and allowed selection of resistant genotypes available for cloning, since the total genetic variance occurred due to the dominance effects. Of the 57 genotypes assessed, those with the lowest genotypic values for reproduction factor were selected as resistant, including: CH3.2, CH3.23, CH3.8, CH3.37, CH3.38, CH3.41, CH3.36, CH2.1, CH2.7, CH1.1, CH1.3 and CH1.2.(AU)