<p>  <em>Heterodera glycines</em> or soybean cyst nematode (SCN) is one of the most yield-limiting soybean plant pathogens. The HG (<em>Heterodera glycines</em>) type test is a greenhouse test to determine the virulence of SCN populations to seven soybean “indicator” lines. Since there has not been a survey of SCN virulence phenotypes in Indiana in over a decade, a total of 124 samples were collected, and all tested positive for SCN. Of 42 selected populations for the HG type test, 88% were virulent to the soybean breeding line PI 88788, from which most SCN-resistant cultivars derive their resistance. All populations were virulent to at least one indicator line, including PI 548402 (‘Peking’), which pose problems for the future of soybean breeding for SCN. <em>Meloidogyne</em> spp. or root-knot nematodes (RKNs) are extremely damaging to agriculture, especially to specialty crops. RKN species are attracted by plant root exudates. The gene expression of <em>M. javanica</em> second-stage juveniles was determined after exposure to tomato root exudates, and the differentially expressed genes were analyzed.</p>

Thesis (M.A. Agricultural Management (Plant Production)) -- University of Limpopo, 2017 / Nemafric-BL and Nemarioc-AL phytonematicides, which are being researched and developed to serve as alternatives to methyl bromide, have not been tested against plant growth and accumulation of essential nutrient elements in watermelon (Citrullus lanatus) cultivars. The objectives of this study were two fold, to determine the (1) overall growth responses and accumulation of selected essential nutrient elements in watermelon cultivars ‘Congo’ and ‘Charleston Gray’ and suppression of Meloidogyne javanica in response to increasing concentrations of Nemafric-BL and Nemarioc-AL phytonematicides, and (2) efficacy of Velum, Nemafric-BL and Nemarioc-AL phytonematicides on growth of watermelon, accumulation of selected essential nutrient elements in leaf tissues of cv. ‘Congo’ and the suppression of population densities of Meloidogyne species. Objective 1 and Objective 2 were achieved under greenhouse and field conditions, respectively. At 56 and 90 days after initiating the greenhouse and field treatments, respectively, the data were collected and subjected to statistical analyses. Nemafric-BL phytonematicide significantly affected growth of watermelon cultivars ‘Charleston Gray’ and ‘Congo’, whereas Nemarioc-AL phytonematicide did not have any significant effects on the plant variables of both cultivars. Generally, plant growth variables and increasing concentrations of Nemafric-BL phytonematicide had density-dependent growth (DDG) patterns, which were quantified through either positive or quadratic equations (Chapter 3). In contrast, both phytonematicides had significant effects on selected nutrient elements in leaf tissues of both watermelon cultivars. The affected nutrient elements, P, Mn and Na versus increasing concentrations of phytonematicides exhibited the DDG patterns, which were also quantified through either positive or quadratic equations (Chapter 3). The phytonematicides were consistent in suppressing nematode numbers in both watermelon cultivars. Comparison of synthetic nematicide Velum and the two phytonematicides under field conditions suggested that, relative to untreated control, the three products each stimulated growth of watermelon cv. ‘Congo’. The efficacy of Nemafric-BL and Nemarioc-AL phytonematicides on suppression of population densities of Meloidogyne species was comparable to that of Velum. In conclusion, Nemafric-BL and Nemarioc-BL phytonematicides were highly effective in managing population densities of Meloidogyne species in watermelon cultivars and also affected the partitioning of selected nutrient elements in tissues. The study provided essential information that could assist in decision-making in nematode management in watermelon production, particularly in fertiliser application.

Thesis (M.Sc.(Plant Protection)) -- University of Limpopo, 2022 / Runner beans are extremely sensitive to root-knot (Meloidogyne species) nematodes. Phytonematicides had been consistently used in managing population densities of Meloidogyne species in various crops, with the application technologies being restricted to the ground leaching technology (GLT) and botinemagation technology, each with its own advantages and disadvantages. The use of seeds as carriers of active ingredients of phytonematicides and then drying prior to sowing, is being considered as another potential application strategy in seeds with hypogeal germination. In such seeds, during seedling emergence the seed cover and the endosperm remain below the soil surface, just above the developing root system. As a result, in phytonematicide-primed seeds, the seed structures could serve as carriers for the active ingredients of phytonematicides. In cucurbitacin phytonematicides, Nemarioc-AL and Nemafric-BL phytonematicides contain cucurbitacin A and B, respectively as active ingredients. The objectives of the study were two-fold, namely, to determine whether runner bean (Phaseolus coccineus L.) seeds would (1) serve as carriers of active ingredients of cucurbitacin-containing phytonematicides without affecting seed germination under in vitro conditions, (2) serve as carriers of cucurbitacins intended for suppression of M. incognita population densities under greenhouse and microplot conditions. Two separate studies were conducted under laboratory conditions, with seven treatment solutions at 0, 2, 4, 8, 16, 32 and 64% Nemafric-BL or Nemarioc-AL phytonematicide. After exposure to separate solutions for 2 h, runner bean seeds were dried on laboratory benches for 72 h. Treatments were arranged in a completely randomised design (CRD), with 8 replications. Two layers of filter papers were placed inside each Petri dish seeded with 10 primed and dried seeds. Petri dishes were incubated inside LABCON growth chamber at 25ºC and 75% relative humidity. Successful seed germination, viewed as emergence of radicle from the testa, was recorded daily for a period of 10 days, with each count being removed from Petri dish to avoid re-counting. Under greenhouse and microplot conditions, primed-and dried seeds were sown in plastic pots containing 2 700 ml steam-pasteurised sandy loam soil, arranged in a randomised complete block design, replicated six times and eight times, respectively. Each seedling was inoculated by distributing 5 000 eggs and second-stage juveniles (J2) of M. incognita race 4 using a 50 ml plastic syringe. Originally, pots were irrigated using 500 ml chlorine-free tapwater, which was reduced to half after seedling emergence at every other day. Plant variables were collected at 56 days after inoculation and data were subjected to the Curve-fitting Allelochemical Response Dose algorithm model. In vitro, germination percentage (R 2 = 0.96), radicle length (R 2 = 0.89) and plumule diameter (R 2 = 0.96) versus Nemarioc-AL phytonematicide exhibited positive quadratic relations. Similarly, the variables versus Nemafric-BL phytonematicide, exhibited positive quadratic relations. In vitro, Mean Concentration Stimulation Point (MCSP) value of Nemarioc-AL phytonematicide on runner bean seeds was 1.05%, whereas for Nemafric-BL phytonematicide MCSP value was 0.58%. Under greenhouse conditions, plant height (R 2 = 0.97), chlorophyll content (R 2 = 0.92), dry shoot mass (R 2 = 0.98), dead nodule number (R 2 = 0.90), total pod number (R 2 = 0.97) and active nodule number (R 2 = 0.93) versus Nemarioc-AL phytonematicide exhibited positive quadratic relations., Similarly, chlorophyll content (R 2 = 0.95), gall rating (R 2 = 0.82), dry shoot weight (R 2 = 0.69), stem diameter (R 2 = 0.85) and total nodule number (R 2 = 0.86) versus Nemafric-BL phytonematicide exhibited positive quadratic relations. Under greenhouse conditions, MCSP values for Nemarioc-AL and Nemafric-BL phytonematicides were 4.18 and 3.69%, respectively. Under microplot conditions, total number of nodules (R 2 = 0.88), number of nodules dead (R 2 = 0.99), number of nodules active (R 2 = 0.95), fresh root mass (R 2 = 0.99), and fresh pod mass (R 2 = 0.99) versus Nemarioc-AL phytonematicide, exhibited positive quadratic relations, whereas plant height (R 2 = 0.85), number of nodules dead (R 2 = 0.87), dry shoot mass (R 2 = 0.97), fresh root mass (R 2 = 0.97) and total number of nodules (R 2 = 0.63) versus Nemafric-BL phytonematicide exhibited positive quadratic relations. Under microplot conditions, MCSP values for Nemarioc-AL and Nemafric-BL phytonematicides were 3.76 and 3.93%, respectively, each with ∑k = 0. All degrees of Nemarioc-AL and Nemafric-BL phytonematicides profoundly reduced nematode numbers under greenhouse and microplot trials. Based on the information obtained from this study, it was confirmed that runner bean (P. coccineus) is sensitive to Nemafric-BL and Nemarioc-AL phytonematicides supported by the Curve-fitting Allelochemical Response Dose (CARD) model results due to most plant variables that had sensitivity values of zero. In conclusion, the priming technology should be developed further since it has the potential of being successful in nematode management in seeds with hypogeal germination / National Research Foundation (NRF) and Potatoes South Africa

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-01-10T09:15:32Z No. of bitstreams: 2 Dissertação - Nayane Oliveira Almeida - 2016.pdf: 4246837 bytes, checksum: 2ee0e2f0ece0d114ea4032c91be4556f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-10T10:58:54Z (GMT) No. of bitstreams: 2 Dissertação - Nayane Oliveira Almeida - 2016.pdf: 4246837 bytes, checksum: 2ee0e2f0ece0d114ea4032c91be4556f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-01-10T10:58:54Z (GMT). No. of bitstreams: 2 Dissertação - Nayane Oliveira Almeida - 2016.pdf: 4246837 bytes, checksum: 2ee0e2f0ece0d114ea4032c91be4556f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The problems caused by nematodes and by the Panama disease on banana plantations are responsible for production losses and limiting to its cultivation. In the state of Goiás there is few information about the nematode genus that affect this crop, and its relationship with the incidence of the fungus Fusarium oxysporum f. sp. cubense (Foc). This research aimed to survey the occurrence of plant parasitic nematodes, the incidence of Foc and soil attributes, and determine if there is a correlation among these factors. In January 2015, twelve banana producing regions in the state of Goiás were sampled: Anápolis, Caiapônia, Goiatuba, Itaguaru, Itumbiara (two areas), Jataí, Morrinhos, Ouro Verde, Palestina, Taquaral and Uruana. All sampled areas, except Morrinhos, revealed contamination with Foc, and all had different genus of nematodes. Meloidogyne sp., Helicotylenchus sp. and Rotylenchus sp. were the main genus of plant parasitic nematodes present in the banana plantations, with Meloidogyne sp. and Rotylenchus sp. the most dominant and abundant genus. We found that Pratylenchus sp. increases the population levels of F. oxysporum and that Helicotylenchus sp. has been affected by the concentration of P, Ca, Mn and the soil pH. / Os problemas fitossanitários causados por nematoides e pela doença mal-do-Panamá, na cultura da banana, são responsáveis por grandes perdas de produção ou são fatores limitantes de seu cultivo. Em Goiás, são escassas as informações sobre os gêneros de nematoides que afetam a bananicultura, bem como sua relação com a incidência do fungo Fusarium oxysporum f. sp. cubense (Foc), agente causal do mal-do-Panamá. Assim, esse trabalho teve por objetivo fazer levantamento da ocorrência de fitonematoides, da incidência de Foc e dos atributos dos solos, e determinar se há correlação entre estes fatores. Em janeiro de 2015, foram amostradas doze regiões produtoras de banana no estado de Goiás, distribuídas em onze municípios: Anápolis, Caiapônia, Goiatuba, Itaguaru, Itumbiara, Jataí, Morrinhos, Ouro Verde, Palestina, Taquaral e Uruana. Todas as áreas amostradas, exceto a do município de Morrinhos, apresentaram-se contaminadas com Foc, e todas apresentaram diversos gêneros de fitonematoides. Meloidogyne sp., Helicotylenchus sp. e Rotylenchus sp. foram os principais gêneros de fitonematoides presentes nos bananais no estado de Goiás, sendo Meloidogyne sp. e Rotylenchus sp. os gêneros mais dominantes e abundantes. Foi constatado que a presença de Pratylenchus sp. aumenta o nível populacional de F. oxysporum e que Helicotylenchus sp. é afetado pelos teores de P, Ca, Mn e pelo pH do solo.

CAPES; Fundação Araucária / O controle biológico e a adição de matéria orgânica ao solo representam as principais alternativas para o controle do nematoide-de-galhas. Os objetivos deste estudo foram avaliar o efeito do subproduto sólido da indústria vinícola (SSIV) sobre o desenvolvimento, in vitro, de Pochonia chlamydosporia e o efeito da associação do SSIV a esse fungo no manejo de Meloidogyne javanica em tomateiros, em casa de vegetação. Para avaliar o efeito direto do SSIV sobre o desenvolvimento do fungo, adicionaram-se as concentrações (0; 5; 10; e 15%) do extrato aquoso do SSIV em meio de cultivo batata-dextrose-ágar (BDA) fundente. Em seguida, a mistura foi vertida em placas de Petri e um disco de meio de cultivo ‘Corn Meal Ágar’ (CMA) colonizado pelo fungo foi colocado no centro de cada placa. Em outro estudo avaliou-se o efeito dos compostos voláteis do SSIV sobre o desenvolvimento de P. chlamydosporia. Para isto, utilizaram-se placas de Petri bipartidas, adicionando em um dos compartimentos as concentrações do SSIV (0,000; 0,065; 0,125; 0,250; e 0,500 g placa-1) e 2 mL de água destilada esterilizada placa-1. No centro do outro compartimento contendo meio de cultivo BDA, adicionou-se um disco de meio de cultivo CMA colonizado pelo fungo. As placas dos dois estudos foram armazenadas em câmara de crescimento, no escuro, a 21°C. Os dois estudos foram realizados duas vezes. Após 14 dias avaliaram-se o diâmetro das colônias e a produção de conídios do fungo. O SSIV reduziu de 9 a 21% o crescimento do fungo nos dois estudos, bem como reduziu a produção de conídios no primeiro estudo. Em casa de vegetação, avaliou-se a associação do SSIV (30 g kg-1 de substrato) às concentrações de P. chlamydosporia com clamidósporos (500; 1.500; 2.500; 3.500; 4.500; e 5.000 clamidósporos g-1 de substrato) ou sem clamidósporos (2,5; 5; 10; e 15 g de inóculo do fungo kg-1 de substrato). Três tratamentos foram utilizados como controle em cada ensaio: adição de P. chlamydosporia (5.000 clamidósporos g-1 de substrato ou 15 g de inóculo do fungo kg-1 de substrato), adição de SSIV (30 g do SSIV kg-1 de substrato) e apenas o substrato. Em seguida, cada saco contendo 4 kg de substrato esterilizado e os respectivos tratamentos foi infestado com 6.000 ovos de M. javanica kg-1 de substrato, homogeneizado e umedecido até 60% de capacidade de campo e armazenado por 14 dias no escuro, a 25 ºC. Depois, o substrato foi transferido para vasos de polipropileno de 500 mL, e uma muda de tomateiro foi transplantada para cada vaso. Após 60 dias foram avaliados a altura, a massa da parte aérea e das raízes frescas e o número de galhas e de ovos do nematoide. A associação do SSIV ao fungo, independentemente do tipo de inóculo do fungo, potencializou o desenvolvimento dos tomateiros e o controle do nematoide. As concentrações mais indicadas do fungo para se associar ao SSIV foram 3.500 clamidósporos g-1 de substrato e 15 g do inóculo sem clamidósporos kg-1 de substrato, pois, além de controlarem efetivamente o nematoide, também proporcionaram o desenvolvimento dos tomateiros. Conclui-se que a associação do SSIV ao fungo P. chlamydosporia potencializa o manejo do nematoide-de-galhas. / The biological control and the addition of organic matter to the soil represent the main alternatives for the control of root-knot nematode. The objectives of this study were to evaluate the effect of solid wine industry by-product (SSIV) on the development, in vitro, of Pochonia chlamydosporia and the effect of combining this fungus with the SSIV on the management of Meloidogyne javanica in tomatoes grown in a greenhouse. To evaluate the direct effect of the SSIV on fungal development, concentrations (0, 5, 10, and 15%) of the aqueous SSIV extract were applied to potato-dextrose-agar (BDA) culture medium. The mixture was then poured into Petri dishes and a disk of 'Corn Meal Agar' (CMA) culture medium colonized by the fungus was placed in the centre of each plate. A further study evaluated the effect of volatile SSIV compounds on the development of P. chlamydosporia. For this, twopart Petri dishes were utilised, to one of the compartments the concentrations of SSIV (0.000, 0.065, 0.125, 0.250, and 0.500 g plate-1) and 2 mL plate-1 sterile distilled water were added. To the other compartment, which contained BDA culture medium, a disc of CMA culture medium colonised by the fungus was added in the centre. The plates from the two studies were stored in a growth chamber in the dark at 21 °C. The two studies were performed twice. After 14 days, the diameter of the colonies and the production of fungal conidia were evaluated. The SSIV reduced fungal growth by 9 to 21% in the two studies, and reduced conidia production in the first study. In the greenhouse, the combination of SSIV (30 g kg-1 of substrate) with the concentrations of P. chlamydosporia with chlamydospores (500; 1,500; 2,500; 3,500; 4,500; and 5,000 chlamydospores g-1 of substrate) or without chlamydospores (2.5, 5, 10, and 15 g of inoculum of fungus kg-1 substrate) were evaluated. Three treatments were used as controls in each assay: the addition of P. chlamydosporia (5,000 chlamydospores g-1 substrate or 15 g of inoculum of fungus kg-1 of substrate), the addition of SSIV (30 g SSIV kg-1 of substrate) and only substrate. Following this, each bag containing 4 kg of sterilised substrate and the respective treatments were infested with 6,000 M. javanica eggs kg-1 of substrate, homogenized, moistened until 60% of field capacity and then stored for 14 days in the dark at 25 °C. The substrate was then transferred to 500 ml polypropylene pots, and one tomato seeding was transplanted into each pot. After 60 days the height, the shoot and fresh root masses, and the numbers of nematode galls and eggs were evaluated. The combination of SSIV and the fungus, independent of the type of fungal inoculum, increased the development of the tomato plants and the control of the nematodes. The fungal concentrations most recommended to combine with the SSIV were 3,500 chlamydospores g-1 of substrate and 15 g of inoculum without chlamydospores kg-1 of substrate, because, besides controlling effectively the nematode, they also improved the development of the tomato plants. It was concluded that the combination of SSIV and the fungus P. chlamydosporia improves the management of this root-knot nematode.

CAPES; Fundação Araucária / O controle biológico e a adição de matéria orgânica ao solo representam as principais alternativas para o controle do nematoide-de-galhas. Os objetivos deste estudo foram avaliar o efeito do subproduto sólido da indústria vinícola (SSIV) sobre o desenvolvimento, in vitro, de Pochonia chlamydosporia e o efeito da associação do SSIV a esse fungo no manejo de Meloidogyne javanica em tomateiros, em casa de vegetação. Para avaliar o efeito direto do SSIV sobre o desenvolvimento do fungo, adicionaram-se as concentrações (0; 5; 10; e 15%) do extrato aquoso do SSIV em meio de cultivo batata-dextrose-ágar (BDA) fundente. Em seguida, a mistura foi vertida em placas de Petri e um disco de meio de cultivo ‘Corn Meal Ágar’ (CMA) colonizado pelo fungo foi colocado no centro de cada placa. Em outro estudo avaliou-se o efeito dos compostos voláteis do SSIV sobre o desenvolvimento de P. chlamydosporia. Para isto, utilizaram-se placas de Petri bipartidas, adicionando em um dos compartimentos as concentrações do SSIV (0,000; 0,065; 0,125; 0,250; e 0,500 g placa-1) e 2 mL de água destilada esterilizada placa-1. No centro do outro compartimento contendo meio de cultivo BDA, adicionou-se um disco de meio de cultivo CMA colonizado pelo fungo. As placas dos dois estudos foram armazenadas em câmara de crescimento, no escuro, a 21°C. Os dois estudos foram realizados duas vezes. Após 14 dias avaliaram-se o diâmetro das colônias e a produção de conídios do fungo. O SSIV reduziu de 9 a 21% o crescimento do fungo nos dois estudos, bem como reduziu a produção de conídios no primeiro estudo. Em casa de vegetação, avaliou-se a associação do SSIV (30 g kg-1 de substrato) às concentrações de P. chlamydosporia com clamidósporos (500; 1.500; 2.500; 3.500; 4.500; e 5.000 clamidósporos g-1 de substrato) ou sem clamidósporos (2,5; 5; 10; e 15 g de inóculo do fungo kg-1 de substrato). Três tratamentos foram utilizados como controle em cada ensaio: adição de P. chlamydosporia (5.000 clamidósporos g-1 de substrato ou 15 g de inóculo do fungo kg-1 de substrato), adição de SSIV (30 g do SSIV kg-1 de substrato) e apenas o substrato. Em seguida, cada saco contendo 4 kg de substrato esterilizado e os respectivos tratamentos foi infestado com 6.000 ovos de M. javanica kg-1 de substrato, homogeneizado e umedecido até 60% de capacidade de campo e armazenado por 14 dias no escuro, a 25 ºC. Depois, o substrato foi transferido para vasos de polipropileno de 500 mL, e uma muda de tomateiro foi transplantada para cada vaso. Após 60 dias foram avaliados a altura, a massa da parte aérea e das raízes frescas e o número de galhas e de ovos do nematoide. A associação do SSIV ao fungo, independentemente do tipo de inóculo do fungo, potencializou o desenvolvimento dos tomateiros e o controle do nematoide. As concentrações mais indicadas do fungo para se associar ao SSIV foram 3.500 clamidósporos g-1 de substrato e 15 g do inóculo sem clamidósporos kg-1 de substrato, pois, além de controlarem efetivamente o nematoide, também proporcionaram o desenvolvimento dos tomateiros. Conclui-se que a associação do SSIV ao fungo P. chlamydosporia potencializa o manejo do nematoide-de-galhas. / The biological control and the addition of organic matter to the soil represent the main alternatives for the control of root-knot nematode. The objectives of this study were to evaluate the effect of solid wine industry by-product (SSIV) on the development, in vitro, of Pochonia chlamydosporia and the effect of combining this fungus with the SSIV on the management of Meloidogyne javanica in tomatoes grown in a greenhouse. To evaluate the direct effect of the SSIV on fungal development, concentrations (0, 5, 10, and 15%) of the aqueous SSIV extract were applied to potato-dextrose-agar (BDA) culture medium. The mixture was then poured into Petri dishes and a disk of 'Corn Meal Agar' (CMA) culture medium colonized by the fungus was placed in the centre of each plate. A further study evaluated the effect of volatile SSIV compounds on the development of P. chlamydosporia. For this, twopart Petri dishes were utilised, to one of the compartments the concentrations of SSIV (0.000, 0.065, 0.125, 0.250, and 0.500 g plate-1) and 2 mL plate-1 sterile distilled water were added. To the other compartment, which contained BDA culture medium, a disc of CMA culture medium colonised by the fungus was added in the centre. The plates from the two studies were stored in a growth chamber in the dark at 21 °C. The two studies were performed twice. After 14 days, the diameter of the colonies and the production of fungal conidia were evaluated. The SSIV reduced fungal growth by 9 to 21% in the two studies, and reduced conidia production in the first study. In the greenhouse, the combination of SSIV (30 g kg-1 of substrate) with the concentrations of P. chlamydosporia with chlamydospores (500; 1,500; 2,500; 3,500; 4,500; and 5,000 chlamydospores g-1 of substrate) or without chlamydospores (2.5, 5, 10, and 15 g of inoculum of fungus kg-1 substrate) were evaluated. Three treatments were used as controls in each assay: the addition of P. chlamydosporia (5,000 chlamydospores g-1 substrate or 15 g of inoculum of fungus kg-1 of substrate), the addition of SSIV (30 g SSIV kg-1 of substrate) and only substrate. Following this, each bag containing 4 kg of sterilised substrate and the respective treatments were infested with 6,000 M. javanica eggs kg-1 of substrate, homogenized, moistened until 60% of field capacity and then stored for 14 days in the dark at 25 °C. The substrate was then transferred to 500 ml polypropylene pots, and one tomato seeding was transplanted into each pot. After 60 days the height, the shoot and fresh root masses, and the numbers of nematode galls and eggs were evaluated. The combination of SSIV and the fungus, independent of the type of fungal inoculum, increased the development of the tomato plants and the control of the nematodes. The fungal concentrations most recommended to combine with the SSIV were 3,500 chlamydospores g-1 of substrate and 15 g of inoculum without chlamydospores kg-1 of substrate, because, besides controlling effectively the nematode, they also improved the development of the tomato plants. It was concluded that the combination of SSIV and the fungus P. chlamydosporia improves the management of this root-knot nematode.

Meloidogyne incognita est le nématode causant le plus de dégâts en agriculture. Sa particularité est d'être un organisme à reproduction asexuée obligatoire. Une femelle engendre des clones a priori 100% identiques génétiquement. Pourtant, M. incognita est capable de faire preuve d'une grande plasticité phénotypique lui permettant de répondre à de nouveaux environnements. Un exemple est le déterminisme du sexe, un phénotype lié aux conditions environnementales et semblant impliquer des régulations chromatiniennes. Un autre exemple est la capacité à contourner les résistances des plantes (virulence), un caractère héréditaire mais non-Mendelien. Dans le cadre de cette thèse, j'ai cherché à tester l'implication des mécanismes épigénétiques dans la plasticité phénotypique en absence de sexe de M. incognita. A ces fins, j'ai évalué la conservation des mécanismes épigénétiques chez les nématodes à galles. Cette approche a permis de pointer que les mécanismes connus chez C. elegans sont conservés chez les nématodes parasites de plantes. Puis, une méthodologie de ChIP-seq a été mise en place afin de comparer les profils d'accumulation des marques d'histones chez M. incognita au cours de la réponse aux conditions environnementales. Cette stratégie a permis la mise en évidence 1- de patrons d'histones modifiées marquant le développement du parasite et 2- de régions génomiques comportant plus de 300 gènes dont des candidats facteurs d'avirulence déjà décrits dans la littérature spécifiquement perdue entre M. incognita (a)virulents. Ces travaux de thèse présentent un intérêt fondamental sur la compréhension de l'évolution d'un organisme en absence de reproduction sexuée. / Meloidogyne incognita is the most damaging plant-parasitic nematode in agriculture. M. incognita reproduces in an asexual way by obligatory parthenogenesis. Genetically identical individuals develop from females and form clonal populations. Although these clones share the same genetic heritage, modifications of their phenotype can be observed when they are exposed to unfavorable environments. This phenotypic plasticity is characterized through two phenotypes of interest: sex-differentiation and virulence (i.e. capacity to parasite a resistant crop). Sex-differentiation varies among environmental conditions and was reported to be linked to decondensed chromatin regions. Virulence is an heritable character transmitted in a non-Mendelian way. Our study focuses on identifying the role of epigenome in the generation of phenotypic variability. To this end we detailed the presence of proteins involved in epigenetic regulations in Meloidogyne spp. We also developed a ChIP-seq assay to compare histone modifications between different developmental stages and between virulent and avirulent parasites. Our results allow to detect specific histone patterns associated with M. incognita development. These results lead us to propose a model that could explain sex determination in M. incognita. We also could link virulence acquisition with the loss of some specific genomic regions that contains more than 300 genes including already described potential avirulence factors. This study opens the way for analyzing the role of epigenetic mechanisms at a whole genome scale, and allows to identify novel biological processes involved in phenotypic variation in asexual organisms.

Espécies de Meloidogyne constituem o principal grupo de fitonematoides causadores de doenças em plantas. São espécies polífagas, distribuídas mundialmente e que se reproduzem profusamente nas mais variadas culturas agrícolas. O fumo não figura exceção, sendo severamente afetado por tais vermes. Globalmente, o controle destas moléstias é realizado essencialmente pela incorporação, em cultivares comerciais, de um único gene de resistência encontrado em Nicotiana tomentosa (gene Rk) e sabidamente efetivo contra às raças 1 e 3 de M. incognita. Todavia, a frequente ocorrência de plantas sintomáticas em cultivos nacionais sugere a existência de outros genótipos de Meloidogyne como agentes etiológicos da doença atualmente. Neste ensejo, realizou-se, no presente estudo, um levantamento das espécies de Meloidogyne ocorrentes em 39 áreas de plantio de fumo na região Sul do Brasil, em cultivares portadoras do gene Rk. Para isto, populações oriundas de raízes infectadas foram estabelecidas e mantidas em plantas de tomate e indivíduos das mesmas foram identificados em nível de espécie por meio da análise de isoenzimas (&alpha;-esterases), da observação de configurações perineais e do sequenciamento da região 18S-ITS1-5.8S do RNA ribossomal. Isolados obtidos a partir destas populações foram estabelecidos a partir de uma única massa de ovos, mantidos em plantas de tomate, agrupados em espécies com base nestes resultados e analisados quanto à patogenicidade em hospedeiros diferenciais e frente a várias características morfométricas. Identificaram-se M. incognita em dezoito amostras (46,2%), M. enterolobii em dez (25,6%), M. javanica em treze (33,3%), M. arenaria em duas (5,1%) e M. inornata em uma (2,6%). Populações mistas também foram encontradas (25,6%). Duas populações (5,1%) morfológica e bioquimicamente atípicas (LGM 27 e LGM 38) foram encontradas, mas com espectro de patogenicidade e sequências de 18S-ITS1-5.8S idênticas a M. enterolobii e M. incognita, respectivamente. Variações intra-específicas foram observadas sob o âmbito patogênico e morfométrico, porém geralmente próximas às suas descrições originais. M. incognita raça 2 foi predominante (79%) e variantes de M. enterolobii foi fato comum (40%). Tendo em vista a elevada ocorrência de M. enterolobii neste levantamento e a escassez de informações acerca de fontes de resistência a esta espécie, buscou-se, também, caracterizar, com base em índice de galhas (IG), a reação (resistência/suscetibilidade) de 97 acessos perante M. enterolobii. Destes, 7 genótipos (J102007T10, J1612008T12, J1612008T34, I112008T97, I112008T98, I112008T99 e I112008T100) foram identificados e avaliados em um segundo experimento. Estes mostraram-se como fontes promissoras de resistência, haja vista que exibiram valores baixos de severidade (IG<1,0). Diante dos resultados, depreende-se a necessidade de incluir resistência a biótipos virulentos, máxime raça 2, de M. incognita, a M. javanica, a M. arenaria e a M. enterolobii em cultivares comerciais. Sob este aspecto, este estudo definiu fontes de resistência para M. enterolobii, constituindo informação inédita na literatura fitonematológica. / Meloidogyne species are undoubtedly the major group of plant parasitic nematodes. Meloidogyne species are polyphagous, worldwide distributed and reproduce profusely in various agronomical crops. Tobacco crop is not an exception, being severely affected by these worms. Worldwide, the control of these diseases is based mainly on the incorporation in commercial cultivars of a single resistance gene found in Nicotiana tomentosa (gene Rk) and known to be effective against races 1 and 3 of M. incognita. However, the frequent occurrence of symptomatic plants in tobacco crops suggests the existence of other genotypes of Meloidogyne as etiological agents of the disease today. Therefore, our study aimed to perform a survey of Meloidogyne species occurring in 39 tobacco growing areas in Southern Brazil, in cultivars carrying the Rk gene. For this, Meloidogyne populations obtained from infected roots were established, maintained on tomato plants and specimens were identified at specific level by isoenzyme analysis (&alpha;-esterase), by analysis of perineal patterns and by sequencing of the 18S- ITS1-5.8S ribosomal RNA region. Isolates obtained from these populations were established from a single egg mass, maintained in tomato plants, grouped into species based on these results and analyzed for host range (pathogenicity) and several morphometric characteristics. From the total of samples, eighteen (46.2%) contained M. incognita, ten (25.6%) M. enterolobii, thirteen (33.3%) M. javanica, one (2.6%) M. arenaria and one (2.6%) M. inornata. Mixed populations were also found in 25.6% of the samples. Two populations (LGM 27 e LGM 38) (5.1%) were morphologically and biochemically atypical, but with host ranges and ITS1-5.8S-18S sequences identical to M. enterolobii and M. incognita, respectively. Intraspecific variations were observed in relation to host range and morphometric characters, but usually close to their original descriptions. M. incognita race 2 was predominant (79%) and strains of M. enterolobii were common fact (40%). Due to the high incidence of M. enterolobii found in this survey and the absence of information about resistance sources to this species, we characterized, based on gall index (GI), the reactions (resistance/susceptibility) of 97 accession of Nicotiana spp. to M. enterolobii. Seven genotypes (J102007T10, J1612008T12, J1612008T34, I112008T97, I112008T98, and I112008T99 I112008T100) were identified and evaluated in a second experiment. These were considered promising sources of resistance, once they exhibited low severity values (IG <1.0). From of our results, it is obviously necessary to include resistance to virulent biotypes (mainly race 2) of M. incognita, M. javanica, M. enterolobii and M. arenaria in commercial cultivars. This study defined resistance sources for M. enterolobii thus providing novel information for the literature related to plant nematodes.

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-02-21T11:58:37Z No. of bitstreams: 1 Andrea Chaves.pdf: 1539586 bytes, checksum: af90f959541cd7c5d31ad1b4d02c65f1 (MD5) / Made available in DSpace on 2017-02-21T11:58:37Z (GMT). No. of bitstreams: 1 Andrea Chaves.pdf: 1539586 bytes, checksum: af90f959541cd7c5d31ad1b4d02c65f1 (MD5) Previous issue date: 2007-01-12 / In Northeastern Brazil the land use of sandy costal table with sugarcane (Saccharum sp.)cropping associated with high temperatures and long dry seasons have increased plant parasitism nematode, particularly Meloidogyne spp. and Pratylenchus zeae, severity in fields. Despite many control measures have been applied, none has been efficient enough to keep nematode level under economic threshold. Therefore three experiments were conducted searching for more efficient, economic and ecological sound control alternatives. In the first experiment, it was evaluated the effect of neen (Azadirachta indica) oil, filter pressed mud and aldicarb on endoparasitic nematodes density and on technological and productive variables of sugarcane in a naturally infested field. There was no significant difference among treatments within technological variables. Stalk diameter and productivity were lower (P= 0.05) in the control and the nematicide treatment. Plants with filter cake (60 t/ha) and filter cake (60 t/ha) + Neen oil (1%) presented the highest (P=¤0.05) productive means, showing no significant difference in plant height and stalk number. Meloidogyne spp. densities in both soil and root were not affected by treatments, in contrast to P. zeae, which presented the lowest (P=H0.05) density in plots with aldicarb or neen oil (2%), indicating efficiency these products under field conditions. In the second experiment, it was evaluated acibenzolar-S-methyl (ASM), silicated fertilizer, and neen extract efficiency on the integrated management of Meloidogyne spp. and P. zeae in a sugarcane field. The association filter cake (50 t/ha) + aldicarb (20 kg/ha) + neen extract (1%) sprinkled on seed stalks significantly increased plant height. ASM (100g/100 L) sprinkled on seed stalks and aldicarb (20 kg/ha) + ASM (100g/100 L) sprinkled on shoots increased (P=o0.05) stalk diameter. The highest (P= 0.05) increases in productivity occurred in plots with filter pressed mud and silicated fertilizer. There was no significant difference in endoparasites densities in soil, incontrast to the roots, in which Meloidogyne spp. densities were significantly lower in plots with silicated fertilizer alone or in association with the other treatments. ASM did not affect root-knot nematode densities and neen extract was efficient only in association with aldicarb or aldicarb + filter cake. Pratylenchus zeae was not affected by any treatment. In the third experiment it was investigated under greenhouse the effects of three mineral organic complexes (Coda Radimax, Coda Humus PK and Coda Vit) on induction of resistance to M. incognita in three sugarcane varieties (RB 92579, RB 863129, RB 867515). All varieties were good host to M. incognita. Comparing to the untreated control, Coda Radimax significantly decreased final number of eggs per root system in all sugarcane varieties. Coda Humus-PK and Coda Vit were efficient in reducing eggs density in RB 867515 but not in RB 863129. All tested compounds did not affect stalk diameter, number and dry weight of shoots. No significant anatomical changes were observed in the M. incognita inoculated tissues examined using bright field microscopy, compared to corresponding tissues in healthy plants. / No nordeste do Brasil o uso de solos arenosos de tabuleiros costeiros com cana-de-açúcar (Saccharum sp.) e as altas temperaturas associadas a longos períodos de estação seca têm favorecido o parasitismo de fitonematoides, particularmente Meloidogyne spp. e Pratylenchus zeae, aumentando a severidade nos campos de cultivo. Embora muitas medidas de controle venham sendo aplicadas, nenhuma tem sido eficiente o suficiente para manter o nível populacional dos fitonematóides abaixo dos níveis de dano. Dessa forma três experimentos foram conduzidos buscando alternativas mais eficientes, econômicas e de menor impacto ambiental. No primeiro experimento, foi avaliado o efeito do óleo de nim, torta de filtro e aldicarb sobre a densidade populacional de nematóides endoparasitos e variáveis produtivas e tecnológicas da cana-de-açúcar em campo naturalmente infestado. Não ocorreram diferenças significativas nas variáveis tecnológicas. O diâmetro dos colmos e a produtividade foram menores (P=Ì0,05) nas testemunhas e no tratamento nematicida isoladamente. As maiores (P= 0,05) médias produtivas foram encontradas nas parcelas com torta de filtro e torta de filtro (60 t/ha) + óleo de nim (1%), não havendo diferença entre altura e número de colmos. A densidade populacional de Meloidogyne spp. no solo e na raiz não sofreu efeito dos tratamentos, diferentemente de P. zeae que apresentou as menores densidades em raízes com nematicida e com o óleo de nim (2%), mostrando eficiência no controle de P. zeae em condições de campo. No segundo experimento, avaliou-se em condições de campo a eficiência dos Acibenzolar-S-Metil (ASM), fertilizante silicatado e extrato de nim no manejo integrado de Meloidogyne spp. e P.zeae. Torta de filtro (50 t/ha) + aldicarb (20 kg/ha) + extrato de nim (1%) pulverizado sobre os rebolos aumentaram (P=[ 0,05) a altura das plantas. ASM (100g/100 L) pulverizado sobre os rebolos e aldicarb (20 kg/ha) + ASM (100g/100 L) promoveram aumentos (P=U0,05) no diâmetro dos colmos. Os maiores (P=U0,05) incrementos produtivos ocorreram nas parcelas com torta de filtro e fertilizante silicatado. Não ocorreu diferença significativa nos níveis dos endoparasitos no solo, diferentemente do que ocorreu nas raízes, quando as densidades de Meloidogyne spp. foram menores (P= 0,05) nas parcelas com fertilizante silicatado isoladamente e em conjunto com os demais tratamentos. ASM não apresentou efeito sobre a densidade deste fitonematóide e o extrato de nim foi eficiente quando usado em conjunto com aldicarb ou aldicarb + torta de filtro. Pratylenchus zeae não foi afetada pelos tratamentos. No terceiro experimento foi investigado, em casa de vegetação, os efeitos de três complexos organo-minerais (Coda Radimax, Coda Humus PK e Coda Vit) na indução de resistência a M. incognita em três variedades (RB 92579, RB 863129, RB 867515) de cana-de-açúcar. Todas as variedades estudadas foram boas hospedeiras de M. incognita. Em relação à testemunha, Coda Radimax reduziu significativamente o número final de ovos porsistema radicular em todas as variedades. Coda Humus-PK e Coda Vit se mostraram eficientes em diminuir (P=I0,05) a densidade de ovos em RB 867515, mas não em RB 863129. Todos os compostos testados não afetaram o diâmetro do colmo, peso da biomassa seca da parte aérea e número de perfilho. Não ocorreram modificações anatômicas significativas nos tecidos das plantas inoculados com M. incognita em relação aos tecidos sadios.

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-03-16T11:54:48Z No. of bitstreams: 1 Douglas Barbosa Castro.pdf: 3531587 bytes, checksum: 22215940a25ea18b769935787dced147 (MD5) / Made available in DSpace on 2017-03-16T11:54:48Z (GMT). No. of bitstreams: 1 Douglas Barbosa Castro.pdf: 3531587 bytes, checksum: 22215940a25ea18b769935787dced147 (MD5) Previous issue date: 2015-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Guava (Psidium guajava L.) farming has a great economic and social importance, especially for the Brazilian semiarid region. Severe damage caused by nematodes parasitism, particularly Meloidogyne enterolobii is reported in orchards across the country, with heavy losses. Neem-based products (Azadirachta indica) have emerged as a sustainable management alternative of these pathogens. The objectives of this study were: (a) evaluate the effects of the neem cake in nematode communities, in the soil microbial activity, soil and plant properties; (b) describe the structure and the composition of nematode communities in guava orchard area recently implemented; (c) to assess variations in the spatial and temporal distributions of plant nematodes and chemical properties of the soil by incorporating the neem cake. The study was conducted in a guava orchard located in a rural settlement in Pernambuco State, Brazil, which was divided into two areas, one of which was applied neem cake treatment. The evaluations were done before treatment, 90 and 180 days after initiation of treatment. Descriptive statistics, covariance and geostatistics was proceeded for nematological data, soil properties and plants nutrition. The results indicated that the neem cake improves soil quality, increasing of organic carbon content, microbial activity and microfauna abundance. Neem cake was effective to control plant parasitic nematode Pratylenchus, however it was not effective against M. enterolobii. The geostatistical analysis revealed that the spherical model fitted for the most of variables studied. Most nematodes not present spatial dependence, featuring pure nugget effect. The contour maps showed that neem cake incorporation increased the variability of soil chemical properties; spatial distribution of essential nutrients for root growth influenced the distribution of plant parasitic nematodes; and the introduction of M. enterolobii in the study area was through infected seedlings. / A cultura da goiabeira (Psidium guajava) é de grande importância econômica e social, especialmente para o semiárido do nordeste brasileiro. Danos severos causados pelo parasitismo por nematoides, principalmente os da espécie Meloidogyne enterolobii, são reportados em pomares de todo país, com elevados prejuízos. Os produtos à base de nim (Azadirachta indica) têm se mostrado uma alternativa para um manejo mais sustentável desses patógenos. Os objetivos do presente estudo foram: (a) avaliar os efeitos da incorporação da torta de nim nas comunidades de nematoides, na atividade microbiana do solo e nos atributos do solo e das plantas; (b) descrever a estrutura e a composição das comunidades de nematoides em área de pomar de goiabeiras recém-implantado; (c) avaliar variações nas distribuições espaço-temporal dos fitonematoides e atributos químicos do solo após a incorporação da torta de nim. O estudo foi conduzido em um pomar de goiabeiras localizado em um assentamento rural no agreste Pernambucano, o qual foi dividido em duas áreas; em uma delas foi aplicado o tratamento com a torta de nim. As avaliações foram feitas antes do tratamento, 90 e 180 dias após o início do tratamento. Procedeu-se com análises de estatística descritiva, covariância e geoestatística para os dados nematológicos, atributos do solo e nutricional de plantas. Os resultados obtidos indicaram que a torta de nim melhora a qualidade do solo, elevando os níveis de carbono orgânico, atividade microbiana e da microfauna. O tratamento foi eficaz em controlar os nematoides do gênero Pratylenchus presentes no solo, no entanto não foi eficaz contra M. enterolobii. A análise geoestatística revelou que o modelo esférico foi o que mais se ajustou às variáveis estudadas e que a maior parte das variáveis nematológicas não apresentou dependência espacial, caracterizando efeito pepita puro. Os mapas de isolinhas mostraram que a incorporação da torta de nim aumentou a variabilidade dos atributos químicos do solo; que a distribuição espacial de nutrientes importantes para o desenvolvimento radicular das plantas influenciou na distribuição de fitonematoides e permitiu concluir que a introdução de M. enterolobii na área se deu por meio de mudas infectadas.