Made available in DSpace on 2015-06-17T19:34:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-20. Added 1 bitstream(s) on 2015-06-18T12:47:06Z : No. of bitstreams: 1 000829026.pdf: 336457 bytes, checksum: 8b02bbfade913853e331d4f14b9e3cc1 (MD5) / A cultura de cana-de-açúcar é de grande importância para a economia brasileira. Os fitonematoides são um dos fatores limitantes na maioria dos canaviais causando grandes perdas à cultura. O manejo dos nematoides é feito através de nematicidas químicos que são prejudiciais ao homem, meio ambiente e produtos colhidos, devido sua alta toxicidade. O controle biológico tem sido uma alternativa viável e sustentável para o manejo dos nematoides. O objetivo do presente trabalho foi avaliar espécies de Bacillus no controle de Meloidogyne incognita e M. javanica in vitro e na cana-de-açúcar. Foram instalados experimentos em condições de laboratório com delineamento inteiramente casualizado com os tratamentos: Cadusafós 200 CS (14 L/ha); B. subtillis; B. firmus e B. amyloliquefaciens (1 e 10 L/ha), além de uma testemunha (água). Os ensaios em vasos, à céu aberto, tiveram delineamento inteiramente casualizado, com os tratamentos B. subtilis (10 L/ha), B. firmus (10 L/ha), B. amyloliquefaciens (10 L/ha), Carbofurano 350 SC (5 L/ha - tratamento padrão) e uma testemunha, com cinco repetições e duas avaliações (100 e 150 dias após inoculação e aplicação dos tratamentos). No ensaio in vitro, B. firmus (10 L/ha) é o mais eficiente para diminuir a eclosão de J2 de M. javanica, sendo estasticamente semelhante ao produto químico testado. Quanto a motilidade de J2 de M. javanica, B. subtilis (10 L/ha) e B. amyloliquefaciens (1 e 10 L/ha), causam a mortalidade do nematoide, porém inferior ao padrão químico testado. Para M. incognita, B. firmus (10 L/ha) proporciona maior eclosão de J2. Quanto a motilidade de J2 de M. incognita, Cadusafós 200 CS (14 L/ha) causou a maior mortalidade. Nos ensaios em vasos, todos os tratamentos aumentam o número de perfilhos, mas não controlam os nematoides / The sugar-cane crop is very important to Brazilian economy. Phytonematodes are among the main limitating factors of such culture causing great losses. Chemical nematicides are harmful to humans, environment, harvested products, and are the main method used to manage the populations of these nematodes. Biological control have been a sustainable alternative to manage these nematodes. The aim of the present study was to evaluate Bacillus species for control Meloidogyne incognita and M. javanica in vitro and in sugar cane plants. We set assays in laboratory conditions in a completely random design with the treatments: Cadusafós 200 CS (14 L/ha), B. subitilis, B. firmus, B. amyloliquefaciens (1 and 10 L/ha) and a control (water). The pot assay, in a semi-field condition, had a completely random design with the treatments: B. subtilis (10 L/ha), B. firmus (10 L/ha), B. amyloliquefaciens (10 L/ha), Carbofurano 350 SC, with five replicates and two evaluation periods (100 and 150 days after inculation and application of treatments). At laboratory assay B. firmus (10 L/ha) was the most efficient in decreasing the M. javanica J2 eclosion and were statistically similar to the chemical nematicide tested. For M. javanica J2 mobility, B. subtilis (10 L/ha) and B. amyloliquefaciens (1 and 10 L/ha) cause nematode mortality, but lower than that presented by the chemical. To M. incognita, B. firmus (10 L/ha) provides higher J2 eclosion. For the M. incognita J2 mobility, Cadusafos 200CS (14 L/ha) caused higher mortality. In the pot assay, all treatments increase the number of tillers but do not control the nematodes

Made available in DSpace on 2015-03-26T13:37:43Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2701343 bytes, checksum: b9c5cc5b07f66e4816776e04f12b0511 (MD5) Previous issue date: 2010-08-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Considering the importance of Meloidogyne enterolobii (= M. mayaguensis) to the culture of guava and the potential of Essential Oil of Mustard (EOM) on nematode control, was aimed to evaluate the efficiency of EOM on control of these nematodes in the field, on a orchard of plants uprooted and cut off at 0.3 m from soil level or in intact plants in production. An orchard of guava trees naturally infested with M. enterolobii, in Viçosa, MG, was selected. EOM was applied on soil at 100 μg/mL, by strips of cardboard in the rhizosphere of intact plants, or by irrigating the cultivation area with EOM diluted in water after the plants have been cut off or uprooted. Samples were collected over 140 days after the product application and evaluated on the number of J2 in soil and number of galls and eggs in roots of tomato plants in the bioassay. The J2 population in soil underwent rapid reduction, regardless of treatment, and was configured as an unreliable variable. By the bioassay, was obtained a reduction of 71%, 81% and 99% for number of galls and 60%, 80% and 83% for number of eggs at 45, 75 and 140 days after application, respectively, for plots treated with EOM, in uprooted or cutted plants. The terbuphos only reduced the number of galls during 45 days. The biological evaluation at 140 days revealed a general trend of population reduction, considering the number of galls and eggs. In intact plants, there was no control of nematodes, as the average variations of J2, galls and eggs did not differ significantly between treatments. In conclusion, the EOM was effective in controlling M. enterolobii at the field in the absence of the host. / Considerando a importância de Meloidogyne enterolobii (= M. mayaguensis) para a cultura da goiabeira e o potencial do óleo essencial de mostarda (OEM) no controle de nematoides, objetivou-se avaliar a eficiência do OEM no controle do nematoide no campo, em pomares de plantas arrancadas, recepadas ou em produção. Selecionou-se um pomar de goiabeiras naturalmente infestado por M. enterolobii, em Viçosa, MG. O OEM foi aplicado no solo a 100 μg/mL, por meio de tiras de papelão na rizosfera de plantas intactas ou irrigando a área de cultivo com OEM diluído em água, após as plantas serem recepadas ou arrancadas. Em amostras coletadas ao longo de 140 dias após aplicação do produto, avaliou-se o número de J2 no solo e número de galhas e ovos em raízes de tomateiros, no teste biológico. Como a população de J2 no solo sofreu rápida redução, independente do tratamento, ela foi considerada uma variável pouco confiável para a avaliação. Pelo teste biológico, obteve-se uma redução de 71%, 81% e 99% para número de galhas e 60%, 80% e 83% para número de ovos aos 45, 75 e 140 dias após a aplicação, respectivamente, para as parcelas tratadas com OEM, em plantas arrancadas ou recepadas. O terbufós reduziu apenas o número de galhas aos 45 dias, o qual voltou a aumentar posteriormente. Aos 140 dias, houve tendência generalizada de redução da população, considerando-se o número de galhas e ovos. Nas plantas intactas não houve controle do nematoide, pois as médias das variações de J2, galhas e ovos não diferiram significativamente entre os tratamentos. Em conclusão, o OEM foi eficiente em controlar M. enterolobii no campo na ausência do hospedeiro.

Orientador: Pedro Luiz Martins Soares / Coorientador: Jaime Maia dos Santos / Banca: Bruno Flávio Figueiredo Barbosa / Banca: Rita de Cássia Panizzi / Resumo: A cultura de cana-de-açúcar é de grande importância para a economia brasileira. Os fitonematoides são um dos fatores limitantes na maioria dos canaviais causando grandes perdas à cultura. O manejo dos nematoides é feito através de nematicidas químicos que são prejudiciais ao homem, meio ambiente e produtos colhidos, devido sua alta toxicidade. O controle biológico tem sido uma alternativa viável e sustentável para o manejo dos nematoides. O objetivo do presente trabalho foi avaliar espécies de Bacillus no controle de Meloidogyne incognita e M. javanica in vitro e na cana-de-açúcar. Foram instalados experimentos em condições de laboratório com delineamento inteiramente casualizado com os tratamentos: Cadusafós 200 CS (14 L/ha); B. subtillis; B. firmus e B. amyloliquefaciens (1 e 10 L/ha), além de uma testemunha (água). Os ensaios em vasos, à céu aberto, tiveram delineamento inteiramente casualizado, com os tratamentos B. subtilis (10 L/ha), B. firmus (10 L/ha), B. amyloliquefaciens (10 L/ha), Carbofurano 350 SC (5 L/ha - tratamento padrão) e uma testemunha, com cinco repetições e duas avaliações (100 e 150 dias após inoculação e aplicação dos tratamentos). No ensaio in vitro, B. firmus (10 L/ha) é o mais eficiente para diminuir a eclosão de J2 de M. javanica, sendo estasticamente semelhante ao produto químico testado. Quanto a motilidade de J2 de M. javanica, B. subtilis (10 L/ha) e B. amyloliquefaciens (1 e 10 L/ha), causam a mortalidade do nematoide, porém inferior ao padrão químico testado. Para M. incognita, B. firmus (10 L/ha) proporciona maior eclosão de J2. Quanto a motilidade de J2 de M. incognita, Cadusafós 200 CS (14 L/ha) causou a maior mortalidade. Nos ensaios em vasos, todos os tratamentos aumentam o número de perfilhos, mas não controlam os nematoides / Abstract: The sugar-cane crop is very important to Brazilian economy. Phytonematodes are among the main limitating factors of such culture causing great losses. Chemical nematicides are harmful to humans, environment, harvested products, and are the main method used to manage the populations of these nematodes. Biological control have been a sustainable alternative to manage these nematodes. The aim of the present study was to evaluate Bacillus species for control Meloidogyne incognita and M. javanica in vitro and in sugar cane plants. We set assays in laboratory conditions in a completely random design with the treatments: Cadusafós 200 CS (14 L/ha), B. subitilis, B. firmus, B. amyloliquefaciens (1 and 10 L/ha) and a control (water). The pot assay, in a semi-field condition, had a completely random design with the treatments: B. subtilis (10 L/ha), B. firmus (10 L/ha), B. amyloliquefaciens (10 L/ha), Carbofurano 350 SC, with five replicates and two evaluation periods (100 and 150 days after inculation and application of treatments). At laboratory assay B. firmus (10 L/ha) was the most efficient in decreasing the M. javanica J2 eclosion and were statistically similar to the chemical nematicide tested. For M. javanica J2 mobility, B. subtilis (10 L/ha) and B. amyloliquefaciens (1 and 10 L/ha) cause nematode mortality, but lower than that presented by the chemical. To M. incognita, B. firmus (10 L/ha) provides higher J2 eclosion. For the M. incognita J2 mobility, Cadusafos 200CS (14 L/ha) caused higher mortality. In the pot assay, all treatments increase the number of tillers but do not control the nematodes / Mestre

O feijão-comum (Phaseolus vulgaris) é atacado por uma gama de patógenos que afetam a produtividade das lavouras e a qualidade dos grãos. Dentre os patógenos de importância econômica para a cultura no Brasil, destaca-se o nematoide das galhas (Meloidogyne incognita). Embora haja relatos sobre a avaliação de cultivares na presença de M. incognita, as fontes de resistência tem se mostrado pouco efetivas. Por isso, pesquisas que possibilitem um melhor entendimento sobre a interação planta-nematoide são de extrema valia e devem nortear novas estratégias para o melhoramento do feijoeiro. Assim, no presente estudo, 18 cultivares de P. vulgaris foram avaliadas quanto à resistência a M. incognita raça 3, sendo que quatro comportaram-se como pouco suscetíveis, 11 como moderadamente suscetíveis e três altamente suscetíveis. A cultivar IPR Saracura mostrou menor grau de suscetibilidade e foi, então, usada na construção de 12 bibliotecas de RNAseq, visando à identificação dos genes envolvidos na reposta à infecção pelo nematoide. Foram adotados dois tratamentos, 4 e 10 DAI (dias após inoculação), compostos de plantas inoculadas e controles. Primeiramente, realizou-se o mapeamento dos transcritos de cada biblioteca, tomando como referência o genoma de P. vulgaris (G19833), o que resultou na identificação de 27.195 unigenes. Em seguida, foi realizada a quantificação da expressão dos transcritos mapeados e genes diferencialmente expressos foram identificados. No total, 191 genes do hospedeiro apresentaram expressão diferencial, considerando-se: i) o tratamento inoculado em relação ao controle; ii) a razão de expressão (Fold Change - FC) mínima absoluta igual a 4; iii) o nível de significância ? = 0,05. Do total, 120 genes foram identificados aos 4 DAI e 71 aos 10 DAI. As sequências mapeadas foram contrastadas àquelas dos bancos de dados NCBI e TAIR, usando a ferramenta BLASTx e, posteriormente, anotadas usando os softwares Blast2GO e MapMan. Detectou-se similaridade com genes codificadores de proteínas conhecidas para 90% (24.604/27.195) dos unigenes, sendo que 69% (16.991/24.604) deles foram anotados. Quanto à expressão diferencial, 98% (188/191) dos transcritos mostraram similaridade com proteínas conhecidas e 67% (127/188) puderam ser anotados. Os transcritos foram atribuídos a diferentes categorias funcionais putativas, predominando o termo ontológico \'processos metabólicos\', em ambas as plataformas. A anotação dos genes na plataforma MapMan mostrou abundância das categorias da via de resposta a estresse, com predominância de genes de defesa superexpressos aos 4 DAI e reprimidos aos 10 DAI. Por fim, 10 genes mostraram expressão diferencial tanto aos 4 como aos 10 DAI: sete deles foram estáveis, sendo superexpressos nas plantas inoculadas, e três apresentaram comportamentos opostos nos momentos avaliados. Ênfase foi dada a um gene que codifica uma \'probable inactive ADP-ribosyltransferase\' e a quatro genes de resposta a ferimento. / The common bean (Phaseolus vulgaris) is attacked by a range of pathogens, which affect crop yield and the quality of grains. Among the pathogens of economic significance to the crop in Brazil, the root-knot nematodes (Meloidogyne incognita) deserve attention. Though there are some reports on cultivar evaluation in presence of M. incognita, the resistance sources have not being effective. Therefore, it is of valuable importance research projects that could lead to a better understanding of plant-nematode interaction and to indicate new strategies for common bean breeding. In the present study, 18 cultivars of P. vulgaris were evaluated in regard to their resistance to M. incognita race 3; four were less susceptible, 11 moderately susceptible, and three were highly susceptible. \'IPR Saracura\' behaved as the less susceptible cultivar and then was selected for the construction of 12 RNAseq libraries, aiming at the identification of genes differentially expressed in response to nematode infection. Two treatments were adopted, 4 and 10 days after inoculation (DAI), each comprised of inoculated and control plants. Firstly, the transcripts were mapped to the reference genome of P. vulgaris (G19833), resulting in the identification of 27,195 unigenes. Then, the mapped transcript\'s expression was quantified and differentially expressed genes were identified. In total, 191 genes of the host plant showed differential expression taking into consideration: i) the inoculated treatments in relation to their control; ii) an absolute fold change (FC) >= 4; iii) a level of significance ? = 0,05. Of the total, 120 genes were detected at 4 DAI and 71 at 10 DAI. The mapped sequences were compared against those deposited in NCBI and TAIR databanks using BLASTx and subsequently annotated using Blast2GO and MapMan softwares. Similarity to known proteins was detected for 90% of the unigenes (24,604/27,195) and 69% (16,991/24,604) of them were annotated. Regarding assessing differential expression, 98% (188/191) of the transcripts showed similarity to known proteins and 67% (127/188) were annotated. Transcripts were attributed to different putative functional categories and the ontological term \'metabolic process\' was predominant within both platforms. Gene annotation within MapMan platform showed predominance of stress-related pathway categories, with prevalence of defense genes overexpressed at 4 DAI and repressed at 10 DAI. Finally, 10 genes showed differential expression at both 4 and 10 DAI: seven were stably overexpressed in the inoculated plants, and three showed an opposite behavior regarding the evaluation periods. Attention was given to a gene encoding a probable inactive ADP-ribosyltransferase and four genes related to wound response.

Du fait de la réduction de l'usage des produits phytosanitaires, les bioagresseurs du sol, notamment les champignons Sclerotinia et les nématodes à galles Meloidogyne, sont de plus en plus préoccupants en maraîchage sous abri. Des techniques alternatives existent, mais leurs efficacités partielles et variables nécessitent la recherche de nouvelles stratégies pour leur gestion.Cette étude vise à déterminer l'intérêt de combiner deux techniques, la solarisation et l'engrais vert (Sorgho sudanense) et les influences des successions culturales et des fréquences d'utilisation de ces techniques sur leurs efficacités.Pour cela, un dispositif en parcelles de producteurs a permis de suivre l'évolution des incidences et sévérités de Sclerotinia et Meloidogyne dans différents systèmes de culture.Les effets des cultures de melon sont prédominants sur ceux des techniques alternatives, de façon opposée pour ces deux bioagresseurs. Les successions incluant du melon favorisent les plus fortes attaques de Meloidogyne alors qu'elles réduisent celles de Sclerotinia. Pour ce pathogène, l'utilisation de solarisation tous les ans ou un an sur deux en combinaison avec l'engrais vert en assure le contrôle le plus efficace. Par contre, la culture de melon étant très sensible à Meloidogyne, elle masque les effets des techniques alternatives.Des propositions d'amélioration de systèmes de culture, basées sur la modification des fréquences de culture du melon et sur l'optimisation de l'usage des techniques alternatives, ont été faites pour la gestion commune de Sclerotinia et Meloidogyne.Ces résultats montrent les interactions entre les différentes pratiques culturales utilisées sur une parcelle et l'intérêt des études agronomiques systémiques. De plus, les effets opposés observés d'un même système de culture soulignent l'intérêt d'études multi-bioagresseurs, pour ne pas faire de propositions qui résolvent un problème mais en aggravent d'autres. / In the current context of the reduction of pesticide use, soilborne pests and diseases, and especially the fungi Sclerotinia and the root-knot nematodes Meloidogyne, become more and more worrying in vegetable production under shelter in Southern France. Alternative techniques exist, but their partial and varying efficiencies require the search for new strategies of management of these pests and diseases fit for producers.Therefore, the aim of this study is to determine the benefit of combinations of two techniques, soil solarisation and green manure (Sorghum sudanense). It is also to determine the influences of crop successions and frequences of these techniques on their individual efficiencies.To this effect, a setup of producers' plots has been designed. The spatiotemporal evolution of incidences and severities of Sclerotinia and Meloidogyne in several cropping systems has been observed on this setup.The presence of a melon crop has a major influence on the efficiency of the alternative techniques. Opposite effects for the two considered pests and diseases appeared. Crops successions with melon are most favourable to highest infestations of Meloidogyne whereas, Sclerotinia infections are reduced. For this pathogen, a solarisation every year or every two years ensures the most effective control. On the contrary, in the case of Meloidogyne, the melon crop is very sensitive to this pest, a characteristic that masks the positive effects of alternative techniques.

Meloidogyne incognita (Kofoid and White) is a major pest of soybean in South Africa and due to its high level of pathogenicity to the crop it is quintessential that research in this regard should receive priority. Root-knot nematode control has in the past mostly included the use of nematicides, while crop rotation and inclusion of cultivars with genetic host plant resistance (henceforth referred to as resistance only) to these pests were also used. Since no synthetically-derived and/or biological agents are registered locally as nematicides on soybean, the use of resistant cultivars represents one of the most viable and environmentally-friendly strategies to protect local soybean crops against damage resulting from parasitism by M. incognita. Although numerous exotic soybean cultivars have been identified with resistance to M. incognita, only a few locally adapted ones have proved to exhibit resistance to the latter species. Moreover, at present Egret is the only cultivar still available for commercial use in South Africa. Little and fragmented information is, however, available on the use of plant enzymes, that are interrelated in biochemical pathways that are expressed in root-knot nematode resistant cultivars, for its use as an additional parameter to exploit such a trait. Therefore, the present study was undertaken to identify M. incognita resistance in selected, locally adapted soybean cultivars by quantifying and exploiting the latter trait by using enzyme activities as an additional parameter. In addition, resistance to M. incognita in selected resistant soybean cultivars was also verified by means of histopathological studies to identify cellular changes associated with the trait. In the first part of the present study, 31 locally adapted soybean cultivars of which 23 were commercially available in the 2012 growing season were evaluated for resistance to M. incognita. The latter was done by means of traditional screening protocols for which M. incognita-gall rating, egg and second-stage juvenile as well as the reproductive factor data per root system for each cultivar screened were recorded. Two greenhouse experiments were subsequently conducted concurrently, one of which the abovementioned nematode parameters were recorded 30 and the other 56 days after inoculation. Reproduction factor values were used as the main criterium to identify M. incognita resistance in local soybean cultivars since it is considered as a more reliable parameter for this specific type of evaluations. Reproduction factor values equal to and lower than one, indicating resistance to the M. incognita population used in this study, were recorded only for cultivar LS5995, as well as seven pre-released GCI cultivars. These eight cultivars also had very low egg, as well as egg and second-stage juvenile counts per root system, all of which differed significantly from the susceptible control, as well as a number of other cultivars. Root gall indices, on the other hand, did not show consistent results in terms of the identification of the host status of the 31 cultivar screened during this study. Using reproduction factor values, local farmers can thus be supplied with information on the resistance of commercially-available soybean cultivars. Eventually, such M. incognita-resistant cultivars can be used to reduce population levels of this nematode pest in fields of producers and also as valuable germplasm sources in breeding programs to introgress/stack this trait in newly-developed soybean cultivars. The second part of the study aimed to verify and exploit M. incognita-resistance in soybean either identified as resistant or susceptible during the screenings experiments, using enzymatic activity as biochemical markers. Cultivar LS5995 was included as the resistant and Dundee as the susceptible standard. The activity of three enzymes, namely guaiacol peroxidase, lipoxygenase and catalase were recorded at different time intervals in roots and leaf samples of the latter cultivars, of both nematode-inoculated and nematode-free plants of each cultivar. Significant (P ≤ 0.05) increases in guaiacol peroxidase activity in leaf and root samples of the M. incognita-resistant cultivars GCI7 and LS5995 (inoculated with J2) were recorded 24 hours (h) after onset of the experiment. Use of this enzyme thus emanated as a useful parameter to identify soybean cultivars that exhibit resistance against M. incognita, especially in leaves, which could substantially reduce the time needed to screen cultivars. In terms of lipoxygenase activity recorded, substantial variation existed between the cultivars tested. The M. incognita-susceptible cultivar Egret was the only cultivar for which a significant (P ≤ 0.05) increase in lipoxygenase activity in the roots was evident 24 h after inoculation. However, during the 48 h sampling time, significant (P ≤ 0.05) differences in lipoxygenase activity were also recorded for the two M. incognita resistant cultivars GCI7 and LS5995. Although the increase in lipoxygenase activity for the susceptible cultivar Egret was unexpected, it may indicate that some level of resistance is present in the latter cultivar, which has in previous studies been identified as resistant to M. incognita. Other factors such as a different M. incognita populations used and temperature differences in greenhouse conditions that applied in this study compared to that for an earlier study may, however, serve as explanations for the latter differences in host status identification of cultivar Egret. In terms of catalase activity recorded in leaf samples of the M. incognita-resistant cultivar LS5995, substantial reductions of as much as 35.6 % were recorded for J2-inoculated plants compared to those of the J2-free control plants. In leaf samples of the susceptible cultivars, Egret and Dundee, catalase was also reduced, but to a lesser extent and ranged from 6 to 26 %. Conversely, catalase activity in the leaves of J2-inoculated plants of the highly susceptible cultivar LS6248R was substantially increased by as much as 29.3 %. Enzyme data obtained as a result of the current study thus generally complemented those of traditional screening assays in which resistance in locally adapted cultivars were identified to a certain degree. It is, however, recommended that enzyme activity, to be used as bio-markers, still needs further refinement and more investigation to optimise their use in identification, verification and exploitation of M. incognita resistance in soybean cultivars. The third and final part of the study encompassed a comparison of cellular changes induced by M. incognita in resistant and susceptible soybean cultivars to verify the resistant reactions expressed in the enzyme data. According to light- and transmission electron microscope observations, distinct differences in the appearance and development of giant cells in roots of the M. incognita-resistant cultivars LS5995 and GCI7 existed when compared to those in roots of the susceptible cultivars Dundee and LS6248R. In the latter cultivars, giant cells that formed were characteristically large and contained a dense cytoplasm, with thick irregularly surfaced cell walls. Cell walls also displayed thick aggregations that appeared to be cell-wall ingrowths. These giant cells are optimal to facilitate M. incognita development and reproduction. In contrast, giant cells that were associated with the resistant cultivars LS5995 and GCI7 were small, irregularly shaped and contained increased amounts of deposited cell-wall material in the cytoplasm known as cell wall inclusions. Necrosis was also present in M. incognita-infected root cells of both cultivars. Such giant cells have been associated with retarded feeding, development and reproduction of the latter root-knot nematode species. However, it was evident that neither GCI7 nor LS5995 are immune to M. incognita since J2 survived and developed to third- and fourth and ultimately mature females that reproduced in their roots. Optimal giant cells that were formed in the roots of the M. incognitasusceptible cultivars Dundee and LS6248R thus supported the nutritional needs of the developing M. incognita individuals and led to significant increases in M. incognita populations 56 days after inoculation as was evident from the high reproduction factor values that were obtained for such cultivars during host status assessments that represented the first part of this study. The opposite was recorded the M. incognita-resistant cultivars LS5995 and GCI7 since sub-optimal giant cells in their roots could not sustain high offspring from such mature females. The presence of necrotic root tissue adjacent to giant cells, furthermore, indicated that hypersensitive reactions occurred in the latter resistant cultivars. Enzyme data obtained in the second part of this study supported the presence of hypersensitive reactions in root cells of the latter resistant cultivars. Guaiacol peroxidase and lipoxygenase inductions in particular in plant tissues have been reported to play integral roles in hypersensitive reactions that are exhibited by cultivars that are resistant to pests and diseases. Finally, results obtained from the different parts of this study complemented each other. It resulted in the resistance that was identified in the GCI7 pre-released cultivar being verified and exploited against that of the resistant standard LS5995. Research that was done during this study also represented the first investigations into the use of enzymes as biochemical markers of resistance against M. incognita in soybean in South Africa. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Meloidogyne incognita (Kofoid and White) is a major pest of soybean in South Africa and due to its high level of pathogenicity to the crop it is quintessential that research in this regard should receive priority. Root-knot nematode control has in the past mostly included the use of nematicides, while crop rotation and inclusion of cultivars with genetic host plant resistance (henceforth referred to as resistance only) to these pests were also used. Since no synthetically-derived and/or biological agents are registered locally as nematicides on soybean, the use of resistant cultivars represents one of the most viable and environmentally-friendly strategies to protect local soybean crops against damage resulting from parasitism by M. incognita. Although numerous exotic soybean cultivars have been identified with resistance to M. incognita, only a few locally adapted ones have proved to exhibit resistance to the latter species. Moreover, at present Egret is the only cultivar still available for commercial use in South Africa. Little and fragmented information is, however, available on the use of plant enzymes, that are interrelated in biochemical pathways that are expressed in root-knot nematode resistant cultivars, for its use as an additional parameter to exploit such a trait. Therefore, the present study was undertaken to identify M. incognita resistance in selected, locally adapted soybean cultivars by quantifying and exploiting the latter trait by using enzyme activities as an additional parameter. In addition, resistance to M. incognita in selected resistant soybean cultivars was also verified by means of histopathological studies to identify cellular changes associated with the trait. In the first part of the present study, 31 locally adapted soybean cultivars of which 23 were commercially available in the 2012 growing season were evaluated for resistance to M. incognita. The latter was done by means of traditional screening protocols for which M. incognita-gall rating, egg and second-stage juvenile as well as the reproductive factor data per root system for each cultivar screened were recorded. Two greenhouse experiments were subsequently conducted concurrently, one of which the abovementioned nematode parameters were recorded 30 and the other 56 days after inoculation. Reproduction factor values were used as the main criterium to identify M. incognita resistance in local soybean cultivars since it is considered as a more reliable parameter for this specific type of evaluations. Reproduction factor values equal to and lower than one, indicating resistance to the M. incognita population used in this study, were recorded only for cultivar LS5995, as well as seven pre-released GCI cultivars. These eight cultivars also had very low egg, as well as egg and second-stage juvenile counts per root system, all of which differed significantly from the susceptible control, as well as a number of other cultivars. Root gall indices, on the other hand, did not show consistent results in terms of the identification of the host status of the 31 cultivar screened during this study. Using reproduction factor values, local farmers can thus be supplied with information on the resistance of commercially-available soybean cultivars. Eventually, such M. incognita-resistant cultivars can be used to reduce population levels of this nematode pest in fields of producers and also as valuable germplasm sources in breeding programs to introgress/stack this trait in newly-developed soybean cultivars. The second part of the study aimed to verify and exploit M. incognita-resistance in soybean either identified as resistant or susceptible during the screenings experiments, using enzymatic activity as biochemical markers. Cultivar LS5995 was included as the resistant and Dundee as the susceptible standard. The activity of three enzymes, namely guaiacol peroxidase, lipoxygenase and catalase were recorded at different time intervals in roots and leaf samples of the latter cultivars, of both nematode-inoculated and nematode-free plants of each cultivar. Significant (P ≤ 0.05) increases in guaiacol peroxidase activity in leaf and root samples of the M. incognita-resistant cultivars GCI7 and LS5995 (inoculated with J2) were recorded 24 hours (h) after onset of the experiment. Use of this enzyme thus emanated as a useful parameter to identify soybean cultivars that exhibit resistance against M. incognita, especially in leaves, which could substantially reduce the time needed to screen cultivars. In terms of lipoxygenase activity recorded, substantial variation existed between the cultivars tested. The M. incognita-susceptible cultivar Egret was the only cultivar for which a significant (P ≤ 0.05) increase in lipoxygenase activity in the roots was evident 24 h after inoculation. However, during the 48 h sampling time, significant (P ≤ 0.05) differences in lipoxygenase activity were also recorded for the two M. incognita resistant cultivars GCI7 and LS5995. Although the increase in lipoxygenase activity for the susceptible cultivar Egret was unexpected, it may indicate that some level of resistance is present in the latter cultivar, which has in previous studies been identified as resistant to M. incognita. Other factors such as a different M. incognita populations used and temperature differences in greenhouse conditions that applied in this study compared to that for an earlier study may, however, serve as explanations for the latter differences in host status identification of cultivar Egret. In terms of catalase activity recorded in leaf samples of the M. incognita-resistant cultivar LS5995, substantial reductions of as much as 35.6 % were recorded for J2-inoculated plants compared to those of the J2-free control plants. In leaf samples of the susceptible cultivars, Egret and Dundee, catalase was also reduced, but to a lesser extent and ranged from 6 to 26 %. Conversely, catalase activity in the leaves of J2-inoculated plants of the highly susceptible cultivar LS6248R was substantially increased by as much as 29.3 %. Enzyme data obtained as a result of the current study thus generally complemented those of traditional screening assays in which resistance in locally adapted cultivars were identified to a certain degree. It is, however, recommended that enzyme activity, to be used as bio-markers, still needs further refinement and more investigation to optimise their use in identification, verification and exploitation of M. incognita resistance in soybean cultivars. The third and final part of the study encompassed a comparison of cellular changes induced by M. incognita in resistant and susceptible soybean cultivars to verify the resistant reactions expressed in the enzyme data. According to light- and transmission electron microscope observations, distinct differences in the appearance and development of giant cells in roots of the M. incognita-resistant cultivars LS5995 and GCI7 existed when compared to those in roots of the susceptible cultivars Dundee and LS6248R. In the latter cultivars, giant cells that formed were characteristically large and contained a dense cytoplasm, with thick irregularly surfaced cell walls. Cell walls also displayed thick aggregations that appeared to be cell-wall ingrowths. These giant cells are optimal to facilitate M. incognita development and reproduction. In contrast, giant cells that were associated with the resistant cultivars LS5995 and GCI7 were small, irregularly shaped and contained increased amounts of deposited cell-wall material in the cytoplasm known as cell wall inclusions. Necrosis was also present in M. incognita-infected root cells of both cultivars. Such giant cells have been associated with retarded feeding, development and reproduction of the latter root-knot nematode species. However, it was evident that neither GCI7 nor LS5995 are immune to M. incognita since J2 survived and developed to third- and fourth and ultimately mature females that reproduced in their roots. Optimal giant cells that were formed in the roots of the M. incognitasusceptible cultivars Dundee and LS6248R thus supported the nutritional needs of the developing M. incognita individuals and led to significant increases in M. incognita populations 56 days after inoculation as was evident from the high reproduction factor values that were obtained for such cultivars during host status assessments that represented the first part of this study. The opposite was recorded the M. incognita-resistant cultivars LS5995 and GCI7 since sub-optimal giant cells in their roots could not sustain high offspring from such mature females. The presence of necrotic root tissue adjacent to giant cells, furthermore, indicated that hypersensitive reactions occurred in the latter resistant cultivars. Enzyme data obtained in the second part of this study supported the presence of hypersensitive reactions in root cells of the latter resistant cultivars. Guaiacol peroxidase and lipoxygenase inductions in particular in plant tissues have been reported to play integral roles in hypersensitive reactions that are exhibited by cultivars that are resistant to pests and diseases. Finally, results obtained from the different parts of this study complemented each other. It resulted in the resistance that was identified in the GCI7 pre-released cultivar being verified and exploited against that of the resistant standard LS5995. Research that was done during this study also represented the first investigations into the use of enzymes as biochemical markers of resistance against M. incognita in soybean in South Africa. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Orientador: Leila Trevisan Braz / Coorientador: Pedro Luiz Martins Soares / Banca: Vanessa dos Santos Paes-Takahashi / Banca: Walter Maldonado Junior / Resumo: Devido ao potencial danoso e existência de inúmeras raças de míldio da alface (Bremia lactucae Regel), vários países realizam a identificação e monitoramento destas raças através do uso de cultivares diferenciadoras de alface. A identificação de resistência a outras doenças importantes nestas cultivares seria de grande valia para o melhoramento da alface, permitindo a seleção simultânea para doenças. Dentre os patógenos de solo, destacam-se os nematoides de galha (Meloidogyne spp.) por seus danos e dificuldade de controle. O presente trabalho teve como objetivo avaliar a resposta das cultivares diferenciadoras de míldio (C-Set) à M. javanica e M. incognita. O experimento foi conduzido em delineamento inteiramente casualizado, com oito repetições e população inicial de 1.000 ovos e juvenis. As avaliações foram realizadas pelos critérios fator de reprodução e índice de reprodução, 75 dias após a inoculação. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste de Scott-Knott a 5% de probabilidade. Todos as cultivares são suscetíveis a M. incognita. As cultivares Argelès, Kibrille, Balesta, Colorado, Design, Bartoli e NunDm15 são classificados como resistentes a M. javanica pelo fator de reprodução e podem ser explorados para seleção simultânea ao míldio e a esta espécie de nematoide. / Abstract: Due to the harmful potential and existence of numerous races of lettuce downy mildew (Bremia lactucae Regel), several countries perform the identification and monitoring of these races through the use of differential lettuce cultivars. The identification of resistance to other important diseases in these cultivars would be of great value for the lettuce's breeding, allowing the simultaneous selection for diseases. Among the soil pathogens, the most important are the root-knot nematodes (Meloidogyne spp.) due to their damage and difficulty of control. In the present work it was evaluated the response of these differential cultivars (C-Set) to M. javanica and M. incognita. The experiment was conducted in a completely randomized design, with eight replications and initial population of 1.000 eggs and juveniles. The evaluations were performed by the criteria of reproduction factor and reproduction index, 75 days after inoculation. Data were submitted to analysis of variance and the means were compared by Scott-Knott test at 5% probability. All cultivars are susceptible to M. incognita. The cultivars Argelès, Kibrille, Balesta, Colorado, Design, Bartoli and NunDm15 are classified as resistant to M. javanica by the reproduction factor and can be exploited for simultaneous selection to mildew and this species of nematode. / Mestre

Orientador: Leila Trevisan Braz / Coorientador: Pedro Luiz Martins Soares / Banca: João Ademir de Oliveira / Banca: Pablo Forlan Vargas / Resumo: Este estudo foi desenvolvido na Faculdade de Ciências Agrárias e Veterinárias (UNESP-FCAV), Câmpus de Jaboticabal- SP, com o objetivo de avaliar o modo de herança da resistência do melão 'Gaúcho Redondo' a Meloidogyne incognita. Para tanto, foi conduzido um experimento em delineamento em blocos casualizados, com três blocos e seis tratamentos, os quais envolveram as linhas parentais 'Gaúcho Redondo' (P1 resistente à M. incognita) e JAB 20 (P2 suscetível, resultado do programa de Melhoramento Genético da Cultura do Melão Rendilhado da UNESP-FCAV), assim como as gerações F1 (P1xP2), F2 (F1xF1), e retrocruzamentos (RC1P1 e RC1P2). Foram avaliadas plantas individuais após 70 dias da inoculação com o patógeno, por meio do fator de reprodução do nematoide (FR), calculado pela contagem do número de ovos e juvenis de segundo estádio, contido na suspensão de cada raiz processada, dividido pela população inicial. A hipótese de herança monogênica foi rejeitada ao nível de significância de 1% de probabilidade no teste do qui-quadrado (χ2), indicando que a resistência está sob controle de mais de um lócus gênico, o que foi confirmado pela análise quantitativa, que evidenciou a existência de seis genes envolvidos na herança da resistência ao nematoide. Houve predominância dos efeitos aditivos no controle da característica em estudo, o que permite resposta aos processos de seleção / Abstract: This study was conducted at the College of Agriculture and Veterinary Sciences (UNESP-FCAV) in Jaboticabal-SP, in order to evaluate the mode of inheritance of resistance of melon 'Gaucho Round' to Meloidogyne incognita. Therefore, an experiment was conducted in randomized block design with three blocks and six treatments, which involved the parental lines 'Gaucho Round' (P1 resistant to M. incognita) and JAB 20 (P2 susceptible result of Breeding Program Culture Melon Tracery UNESP-FCAV), as well as the F1 (P1xP2), F2 (F1xF1) and backcross (RC1P1 and RC1P2). Individual plants were evaluated 70 days after inoculation with the pathogen through the nematode reproduction factor (FR), calculated by counting the number of eggs and second stage juveniles contained in the suspension of each root processed, divided by the initial population . The hypothesis of monogenic inheritance was rejected at a significance level of 1% probability in the chi-square (χ2), indicating that resistance is under the control of more than one gene locus, which was confirmed by quantitative analysis, which showed the existence of six genes involved in inheritance of resistance to nematodes. Predominance of additive effects in controlling the trait under study, allowing response to selection processes / Mestre

O gênero Eucalyptus possui diversas espécies que apresentam grande valor comercial, sendo utilizado principalmente para produção de energia (carvão e lenha) e celulose-papel. Na literatura, entretanto, existem poucas informações acerca de nematoses nessa cultura. Além dessa carência e de sua importância econômica, o eucalipto é comumente cultivado em locais de alta incidência de Pratylenchus brachyurus e Meloidogyne incognita, além de ser consorciado com diversas outras culturas intolerantes, como por exemplo a soja. Dessa forma há uma necessidade de conhecer a reação das espécies de eucalipto a estes nematoides. Dito isso, o presente trabalho teve por objetivo testar a reação de algumas espécies de eucalipto a P. brachyurus e M.incognita. Foram realizados 6 experimentos, 5 envolvendo o nematoide das lesões e 1 com o nematoide de galhas. Os tratamentos foram inoculados com uma população inicial de nematoides e, após 90 dias, estimava-se o fator de reprodução (FR) e nematoides por grama de raiz (Nem/g). Adotou-se o critério baseado em Oostenbrink (1966), onde a espécie foi considerada suscetível quando apresenta FR >= 1 e resistente quando FR < 1. Dos eucaliptos testados, 6 apresentaram reação suscetível e 4 reação resistente para P. brachyurus. As espécies com maiores FR estão entre as mais utilizadas no Brasil, exceto E. saligna. Ressalta-se que estas não necessariamente são resistentes, necessitando apenas de um período maior para o estabelecimento do patógeno. Observou-se indícios de que E. saligna e E. camaldulensis sejam intolerantes a P.brachyurus. Para M. incognita raça 3 todas as espécies testadas foram resistentes. Aconselha-se a realização de experimentos com períodos superiores a 100 dias para uma correta classificação da reação de hospedeiro. O eucalipto é uma opção para aproveitamento de áreas infestadas com M. incognita raça 3, porém seu uso mostra-se um risco em áreas infestadas com P. brachyurus. / The Eucalyptus has several species with high commercial value and is used mainly for energy purpose (Charcoal and firewood) and paper. In the literature, however, there is little information about plant parasitic nematodes in this woody specie. In addition to this lack and its economic importance, eucalypts is also commonly cultivated in areas with high incidence of Pratylenchus brachyurus and Meloidogyne incognita, and consorted with several intolerant crops, such as soybean. Thus, there is a need to know the host status of the eucalypts species to these nematodes. With that, this work aimed to test the reaction of some Eucalyptus species to P.brachyurus and M. incognita. For this purpose six experiments were performed, five to test the lesion nematode and one to test the root-knot nematode. The treatments were inoculated and, after 90 days, it was estimated the reproduction factor (FR) and nematodes per gram of root (Nem/g). The present work adopted the criteria based on Oostenbrink (1966), where the species was considered susceptible when presenting FR >= 1 and resistant when FR < 1. Of species tested, six were susceptible hosts and four resistant host to P. brachyurus. The species with highest FR are among the most used eucalypts in Brazil, except E. saligna. It is emphasized that those species with FR < 1 are not necessarily resistant, requiring only a longer period for the pathogen establishment. There was some evidence that E. saligna and E. camaldulensis are intolerant hosts to P. brachyurus. To M. incognita Race 3 all tested species were resistant. It is advisable to perform experiments for periods longer than 100 days to a correct classification of host status. Eucalyptus is an option for utilization of areas infested with M. incognita race 3, but its use appears to be a risk in Pratylenchus brachyurus infested areas.