Submitted by (lucia.rodrigues@ufrpe.br) on 2017-03-14T12:33:28Z No. of bitstreams: 1 Jeane Emili de Medeiros.pdf: 394630 bytes, checksum: 1eb59fc3e8a4ae913b395a21c71fbe51 (MD5) / Made available in DSpace on 2017-03-14T12:33:28Z (GMT). No. of bitstreams: 1 Jeane Emili de Medeiros.pdf: 394630 bytes, checksum: 1eb59fc3e8a4ae913b395a21c71fbe51 (MD5) Previous issue date: 2007-02-26 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The objective of this work was to isolate and select bacteria for the control of Meloidogyne incognita and to evaluate the isozymatic activity of melon plants parasitized. Sixty-one rhizobacterium isolates obtained from rhizosphere soil and 56 endophytic obtained from the Culture Collection of Plant Bacteriology Laboratory - Federal Rural University of Pernambuco were tested. Melon seedlings yellow type 10 days old had their soil infested with 1000 eggs of Meloidogyne incognita race 2. Two days before soil infestation 20 mL of bacterial suspension (0,7 OD) were deposited in each pot. After 60 days fresh biomass of shoot and root , gall index, egg mass index and nematode reproduction factor were determined. Among 117 isolates the endophytic ENM7, ENM10 and ENM51 were selected because they significantly reduced egg mass index and/or gall index. However when tested again, separately or in mixtures, these isolates did not maintain their efficiency and besides they did not affect egg hatching in vitro. In order to study the activity of the isozymes α and β-esterase, peroxidase, acid phosphatase and malate dehydrogenase, plants of melon with 10 days old, had their soil infested with 500 nematode eggs per plant, and maintained in greenhouse. At 2, 4, 6, 8, 16, 24 e 32 days after soil infestation the third leaf of each plant was collected and processed for electrophoresis of isozymes in polyacrilamide gel. Only β-esterase and malate dehydrogenase showed polymorphism between bands expressed by plants parasitized by nematodes when compared to the control plants. The nematode inhibited the expression of some β-esterase genes and activated the expression of other malate dehydrogenase genes. / O objetivo dessa pesquisa foi isolar e selecionar bactérias para o controle da meloidoginose e avaliar a atividade isoenzimática de plantas de meloeiro parasitadas por Meloidogyne incognita raça 2. A partir de solo rizosférico de meloeiro foram obtidos 61 isolados de rizobactérias que juntamente com 56 isolados endofíticos pertencentes à Coleção de Culturas do Laboratório de Fitobacteriologia da UFRPE foram testados. Plântulas de meloeiro Amarelo com 10 dias tiveram o solo infestado com 1000 ovos de M. incognita raça 2. Dois dias antes da infestação do solo foram depositados 20 mL da suspensão bacteriana (0,7 A) por vaso. Decorridos 60 dias, foram determinadas as biomassas frescas da parte aérea e das raízes, os índices de galhas e de massa de ovos e o fator de reprodução do nematóide. Dos 117 isolados testados, foram selecionados inicialmente os endofíticos ENM7, ENM10 e ENM51 que reduziram significativamente o índice de massa de ovos e/ou o índice de galhas. Contudo, quando testados novamente, separadamente ou em misturas, esses isolados não mantiveram a eficiência na redução dessas variáveis e in vitro também não afetaram a eclosão dos juvenis. Para o estudo da atividade das isoenzimas α e β-esterase, peroxidase, fosfatase ácida e malato desidrogenase, plantas de meloeiro com dez dias de idade, tiveram o solo infestado com 500 ovos do nematóide por planta, sendo mantidas em casa de vegetação. Aos 2, 4, 6, 8, 16, 24 e 32 dias após a infestação do solo a terceira folha das plantas foi coletada e submetida à eletroforese de isoenzimas em gel de poliacrilamida. Apenas a β-esterase e a malato desidrogenase mostraram polimorfismo entre as bandas expressas pelas amostras das plantas parasitadas por nematóides, quando comparadas às plantas testemunhas. A presença do nematóide inibiu a expressão de alguns genes β-esterase e ativou a expressão de outros da malato desidrogenase.

Orientador: Leila Trevisam Braz / Coorientador: Pedro Luiz Martins Soares / Banca: Vanessa dos Santos Paes Takahashi / Banca: Letícia Akemi Ito Pontes / Resumo: A alface é a principal hortaliça folhosa cultivada no mundo, sendo a mais comercializada a do tipo crespa. Com o cultivo consecutivo na mesma área, vários fatores podem prejudicar a produtividade, se destacando os danos causados pelos nematoides de galha, Meloidogyne spp. Este trabalho teve como objetivo avaliar vinte cultivares de alface, do grupo crespa, quanto a reação à Meloidogyne incognita, M. javanica e M. enterolobii. Foram realizados três ensaios, um para cada espécie de nematoide. Os experimentos foram conduzidos em casa de vegetação, em vaso com substrato autoclavado. O delineamento experimental foi em blocos casualizados, com cinco repetições. As plantas foram inoculadas com 1.000 ovos e eventuais juvenis de segundo estádio do nematoide, no dia do transplantio das cultivares. O tomateiro 'Rutgers' foi utilizado como padrão de viabilidade do inóculo de cada espécie de nematoide. As variáveis avaliadas foram: número total de ovos e juvenis do segundo estádio (NTOJ), fator de reprodução (FR) e número de ovos e juvenis de segundo estádio por grama de raiz (NOJGR) avaliadas 60 dias após a inoculação. Os resultados obtidos mostraram que as cultivares Verônica, Grand Rapids e Crespa para Verão foram resistentes as espécies M. enterolobii, M. incognita, M.javanica. As cultivares Thaís, SRV 2005 e Marisa foram resistentes as espécies M. incognita e M. javanica. A cultivar Black Seed Simpson foi resistente à M. enterolobii. As cultivares Vanda e Mônica SF 31 foram resistent... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Lettuce is the main leafy vegetable grown in the world, in marketing the lettuce curly leaf type is predominant. With consecutive cultivation in same area several factors may impair productivity, highlighting the damage caused by root-knot nematodes, Meloidogyne spp. This work aimed to evaluate the reaction of twenty cultivars curly leal lettuce to Meloidogyne incognita, M. javanica e M. enterolobii. Three tests were conducted one for each nematode species. The experiment was carried out in a greenhouse, in pots with sterilized substrate. The design was a randomized block, with five repetitions. Seedlings were inoculated with 1000 eggs and second-stage juveniles of the nematode test per pot, on the day of transplantation of the cultivar. The tomato 'Rutgers' was used as inoculum viability standard for each specie tested. The variables evaluated were : reproduction factor (FR), total eggs number and juveniles (NTOJ) and eggs number and juveniles by root gram(NOJGR), 60 days after inoculation. The results showed that among cultivars Veronica, Grand Rapids and Crespa para Verão were the resistant to the nematode species in the study. The cultivars Thaís, SRV 2005 and Marisa were resistant to species M. incognita e M. javanica. To cultivate Black Seed Simpson was resistant to M. enterolobii. The cultivars Vanda and Mônica SF 31 were resistant to M. incognita. The cultivars Crespa, Rubia, Cinderela and Veneranda were resistant to M. javanica / Mestre

Thesis (M.Agric. (Plant Production)) -- University of Limpopo, 2018 / Meloidogyne incognita race 2 is internationally recognised as one of the most aggressive Meloidogyne species and it is also widely distributed in Limpopo Province, where it occurs alone or as mixed populations with other Meloidogyne species. Traditionally, Meloidogyne species had been managed using synthetic chemical nematicides, most of these products had been withdrawn from agro-chemical markets due to their environment-unfriendliness. Following the withdrawal of synthetic chemical nematicides, nematode resistance had been the most preferred strategy for managing high nematode population densities. The availability of nematode resistant genotypes in sweet potato (Ipomoea batatas) would enhance the use of resistance in managing Meloidogyne species and races in Limpopo Province. Generally, should post-infectional nematode resistance be available in the test sweet potato cultivars, the information would be relayed to plant breeders for use as source of introgression in various commercial cultivars where nematode-resistant genotypes do not exist. The objectives of the study, were to determine: (1) Host-status and host-sensitivity in sweet potato cv. ʹBopheloʹ, ʹBosbokʹ and ʹMvuvheloʹ to M. incognita race 2. (2) the existing nematode resistance mechanism in any of the test cultivars that had resistance to M. incognita race 2. For achieving Objective 1, eight treatments namely, 0, 25, 50, 125, 250, 625, 1250 and 3125 eggs and second stage-juveniles (J2) M. incognita race 2 were used under greenhouse trials for each cultivar. To achieve Objective 2, sweet potato plants were inoculated with 100 J2 with four plants harvested every other day for 30 days counting to 15 harvesting times. At 56 days after inoculation, cv. ʹBopheloʹ had reproductive factor (RF) values above unity for M. incognita race 2 and plant growth variables were reduced. Therefore, the cultivar was a susceptible host to M. incognita race 2 and mechanism trial was not conducted for this cultivar. Meloidogyne incognita race 2 failed to reproduce on cultivars ʹBosbokʹ and ʹMvuvheloʹ whereas nematode infection did not affect plant growth and therefore, the two cultivars were resistant to M. incognita race 2. Mechanisms of resistance to M. incognita race 2 on cultivars ʹBosbokʹ and ʹMvuvheloʹ demonstrated significance existence of (1) necrotic spots, (2) poorly developed giant cells, (3) formation of rootlet interferences (4) absence of root galls and (5) non-detectable J2 in roots. All these features suggested the existence of post-infectional nematode resistance in the two cultivars to M. incognita race 2. In conclusion, cultivar ʹBopheloʹ was susceptible to M. incognita race 2, whereas cultivars ʹBosbokʹ and ʹMvuvheloʹ were resistant to M. incognita race 2, with the evidence of post-infectional nematode resistance to the nematode species

The interaction of herbicides and Northern root-knot nematodes (Meloidogyne hapla Chitwood) on onions and beans was studied in the greenhouse. Seeds of onions (Allium cepa L.) were planted in soil treated with defferent levels of dimethyl 2,3,5,6-tetrachloroterephthalate (DCPA). Seeds of beans (Phaseolus vulgaris L.) were planted in soil treated with different levels of DCPA or α, α, α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin). Seedlings were inoculated with root-knot nematode larvae after 2 week's growth. DCPA reduced root and shoot growth on onions but did not significantly affect bean growth. Trifluralin significantly reduced root and shoot growth of beans. Growth reduction was directly related to the concentration of DCPA or trifluralin. Anatomical studies on onion roots indicated that the epidermal cells were seriously affected by DCPA treatment. They were greatly misshapen, overlapped, and in various stages of apparent dissolution or collapse. Symptoms were more severe under higher concentrations. Macroscopic examination of roots treated with DCPA or trifluralin showed soil particles strongly adhered to root tissue. DCPA-treated and non-treated nematode larvae were equally pathogenic on onions. Both DCPA and trifluralin significantly reduced the number of nematode galls formed on beans and onions grown in treated soil.

Abamectin is a blend of B1a and B1b avermectins that is being used as a seed treatment to control plant-parasitic nematodes on cotton. Data on the toxicity of abamectin and its effectiveness as a seed treatment to control Meloidogyne incognita or Rotylenchulus reniformis on cotton are lacking. The toxicity of abamectin was based on an assay of nematode mobility, LD50 values of 1.56 µg/ml and 32.9 µg/ml were calculated based on 2 hr exposure for M. incognita and R. reniformis, respectively. There was no recovery of either nematode after exposure for 1 hr to its LD50 concentration. Sublethal concentrations greater than 0.39 µg/ml for M. incognita and 8.2 µg/ml for R. reniformis reduced (P = 0.05) infectivity on tomato. In field trials, suppression (P = 0.05) of M. incognita was observed 32 DAP by abamectin seed treatment whereas no suppression of R. reniformis was observed. No suppression of M. incognita was perceived by abamectin seed treatment in microplots. Suppression of M. incognita was observed in microplots by harpinEA and harpingαβ as a seed treatment and foliar spray, respectively. Seed cotton yields were variable for abamectin-treated seed, but numerically positive for harpin-treated cotton. Initial gall formation on developing taproots was suppressed (P = 0.001), and penetration of 5-cm long taproots by M. incognita and R. reniformis was numerically suppressed by abamectin-treated compared to non-treated seed, but infection increased with root development. Using an assay of nematode mobility, the proportion of dead second-stage juveniles (J2) was higher (P = 0.05) following exposure to an excised radicle from abamectin-treated seed than non-treated seed, but lower (P = 0.05) than J2 exposed to the abamectin-treated seed coat. Thus a higher concentration of abamectin remained on the seed coat than emerging radicle. The concentration of abamectin transferred from the seed coat to the developing roots was limited, which contributed to the variability in suppression of plant-parasitic nematodes on cotton.

S'avaluaren 58 soques de Pseudomonas fluorescens i Pantoea agglomerans per la seva eficàcia en el biocontrol de la malaltia causada per l'oomicet Phytophthora cactorum en maduixera i pel nematode formador de gal·les Meloidogyne javanica en el portaempelt GF-677.Es desenvolupà un mètode ex vivo d'inoculació de fulla amb l'objectiu de seleccionar soques bacterianes com a agents de control biològic de P. cactorum en maduixera. Tres soques de P. fluorescens es seleccionaren com a soques eficaces en el biocontrol del patogen en fulles i en la reducció de la malaltia en plantes de maduixera. La combinació de soques semblà millorar la consistència del biocontrol en comparació amb les soques aplicades individualment.Tres soques de P. fluorescens es seleccionaren per la seva eficàcia en la reducció de la infecció de M. javanica en portaempelts GF-677. La combinació d'aquestes soques no incrementà l'eficàcia del biocontrol, però semblà reduir la seva variabilitat. / 58 Pseudomonas fluorescens and Pantoea agglomerans strains were evaluated for their biocontrol efficacy against the oomycete Phytophthora cactorum in strawberry and the root-knot nematode Meloidogyne javanica in GF-677 rootstocks.An ex vivo detached leaf inoculation method was developed to select bacterial strains as biological control agents of P. cactorum in strawberry. Three P. fluorescens strains were selected as effective in biocontrol of the pathogens on leaves and in disease reduction in strawberry plants. Combination of strains improved biocontrol consistency compared to strains applied individually. Three P. fluorescens strains were selected for their efficacy in M. javanica infection reduction in GF-677 rootstocks. Combination of these strains did not increase biocontrol efficacy, but reduced its variability.

Abamectin is a blend of B1a and B1b avermectins that is being used as a seed treatment to control plant-parasitic nematodes on cotton. Data on the toxicity of abamectin and its effectiveness as a seed treatment to control Meloidogyne incognita or Rotylenchulus reniformis on cotton are lacking. The toxicity of abamectin was based on an assay of nematode mobility, LD50 values of 1.56 µg/ml and 32.9 µg/ml were calculated based on 2 hr exposure for M. incognita and R. reniformis, respectively. There was no recovery of either nematode after exposure for 1 hr to its LD50 concentration. Sublethal concentrations greater than 0.39 µg/ml for M. incognita and 8.2 µg/ml for R. reniformis reduced (P = 0.05) infectivity on tomato. In field trials, suppression (P = 0.05) of M. incognita was observed 32 DAP by abamectin seed treatment whereas no suppression of R. reniformis was observed. No suppression of M. incognita was perceived by abamectin seed treatment in microplots. Suppression of M. incognita was observed in microplots by harpinEA and harpingαβ as a seed treatment and foliar spray, respectively. Seed cotton yields were variable for abamectin-treated seed, but numerically positive for harpin-treated cotton. Initial gall formation on developing taproots was suppressed (P = 0.001), and penetration of 5-cm long taproots by M. incognita and R. reniformis was numerically suppressed by abamectin-treated compared to non-treated seed, but infection increased with root development. Using an assay of nematode mobility, the proportion of dead second-stage juveniles (J2) was higher (P = 0.05) following exposure to an excised radicle from abamectin-treated seed than non-treated seed, but lower (P = 0.05) than J2 exposed to the abamectin-treated seed coat. Thus a higher concentration of abamectin remained on the seed coat than emerging radicle. The concentration of abamectin transferred from the seed coat to the developing roots was limited, which contributed to the variability in suppression of plant-parasitic nematodes on cotton.

Root-knot disease caused by Meloidogyne spp. is the most important nematode disease of peanut. Even though many management strategies have been applied to control this disease on peanut, resistance is the most recommendable. Marker-assisted selection has been used as a useful tool for screening of resistant individuals in segregating populations. However, it requires many laborious steps. Thus, there is a need for PCR - based markers, which are more practical, rapid, and efficient. In this study, we tried to develop a SCAR marker linked to root-knot nematode resistance locus in peanut based on the RFLP marker R2430E. The entire sequence of R2430E was 2217 bp and contained one putative open reading frame (ORF) of 713 nucleotides. Thirteen primers including 5 forward and 8 reverse primers were synthesized to sequence the entireR2430E. Based on the results of BLAST searches, R2430E appeared to encode an AAA ATPase containing von Willebrand factor type A (VWA) domain from Magnetococcus sp. MC-1 (106 bits). To determine if there is a portion of the R2430E that hybridizes only to a band co-segregating with the resistance locus, we generated 4 probes spanning different parts of the gene. Southern analysis using these probes revealed identical banding patterns for each probe. Therefore, we concluded that there is very limited if any sequence polymorphism between different alleles detected by the R2430E probe. Additionally, this conclusion is supported by the experiment in which we tested 25 primer pairs derived from the R2430E using genomic DNA from both resistance and susceptible genotypes. In this experiment, all primer pairs amplified identical PCR fragments, suggesting again that there is little or no sequence divergence between putative alleles as differentiated by southern blotting. To identify possible single nucleotide polymorphisms (SNPs) between polymorphic R2430E RFLP bands, we cloned several fragments that span the entire R2430E transcribed sequence. Surprisingly, no SNPs were identified in the transcribed region of this gene. We propose that polymorphism detected by this RFLP marker is outside of the R2430E.

Experiments were conducted in the greenhouse, field and growth chambers to evaluate effects of soil type, soil moisture regimes, and porosity on selected aspects of the dynamics of the Kona coffee root-knot nematode, Meloidogyne konaensis. First, the reproduction and damage potential of M. konaensis on resistant and susceptible rootstocks of coffee in four soils under two moisture regimes representative of areas where coffee is grown in Hawaii were assessed in greenhouse experiments. M. konaensis suppressed growth of coffee in all four soils. Nematode reproduction occurred readily in all soil types. Reproduction was lowest in the Hydric Dystrandept soil where the nematode holotype was found. In contrast, root galling was greatest in this soil. Greater galling occurred under constant moisture (33kPa) than under fluctuating moisture conditions in this soil. A field experiment in Kainaliu, Hawaii was conducted to determine the influence of irrigation, plant age, cultivar and nematode on coffee growth and yield. The population densities of the nematode in the soil varied according to plant age and irrigation treatment. Soil populations under irrigated conditions were greater during the months of May to July which normally follows the greatest annual precipitation and a period of active plant growth. Nematode reproduction was greater on coffee transplanted as 6-month-old seedlings than on coffee transplanted at 12- month ofage. Soil water tension varied by season and experimental treatment. Trees from 12-month-old transplants exhibited greater water tension fluctuation with greatest water tension occurring from January to April. Trees transplanted as 6-month-old seedlings into M. konaensis infested soil and irrigated yielded greater coffee fruit than the same aged trees treatment without irrigation. Crop loss and reduction of growth and yield were also more evident from 6-month-old seedlings without supplemental irrigation treatment. In contrast, yield from plots in treatments including irrigation, nematode and 12-month-old transplants yielded poorly. Overall highest yields were obtained from trees free of nematode and with supplemental irrigation. Yield reductions from nematode-infected plants ranged from 30-60% which is economically significant. Penetration, development and reproduction of M. Iwnaensis was determined on tomato as model plant at 0.77 and 0.65 porosity. The rate of root penetration and post-embryonic developmental rates occurred slightly faster the porosity treatment of 0.77 than in the more densely packed soil (porosity of 0.65). Development in the 0.65 porosity progressed slower than at 0.77. Even though the nematodes matured faster and began laying eggs sooner on plants growing at porosity of 0.77, much greater numbers of eggs were laid by 30 days after inoculation at the 0.65 porosity treatment than those at the 0.77 porosity. The finding from this research illustrates the primary role of the Kona coffee root-knot nematode in the Coffee Decline. The soil environment and host suitability are conducive factors for the coffee decline disease. Proper soil moisture management combined with sources of genetic resistance could minimize the damage enabling the coffee industry to remain profitable.

[Truncated abstract] Nematodes are known to significantly affect productivity of grapevines worldwide. Although major surveys have been carried out on nematodes infesting roots of grapevines elsewhere, only a preliminary survey has been carried out in Western Australia (W.A.). This study on the effect of irrigation systems on pathogenicity of nematodes on vines commenced with a survey of nematodes in two major grapegrowing regions of W.A. In this survey, soil samples were taken from 5 vineyards from Margaret River and 7 vineyards from Swan Valley regions of the state. Root-knot nematode (Meloidogyne spp.) was found to be the dominant genus in both major grape growing regions. Meloidogyne spp. occurred 76% and 75% of total soil sample in Margaret River and Swan Valley. The highest density of Meloidogyne spp. was 7 nematodes/g soil in Margaret River and 3.17 nematodes/g soil in Swan Valley. In both regions, other plant parasitic nematodes were recorded that included the root lesion (Pratylenchus spp.), dagger (Xiphinema spp.) and stubby (Trichodorus spp.) nematodes. Paratylenchus spp. were found in a few soil samples from Margaret River region, and Helicotylenchus spp. were found only in Swan Valley region, but was widespread. Some vineyards have established only resistant cultivars (Schartzman, Ramsey and 34 EM) resistant to nematodes. In these vineyards total nematode population was lower than most of other vineyards. However, in comparison of nematode numbers between cultivars, there were lower number of nematodes in some susceptible cultivars than in the resistant cultivars. Most common nematode taxa were Meloidogyne, Pratylenchus and Xiphinema in both regions. Root-knot and root lesion nematodes were the most widespread and economically important genera. These two genera are known to have different life cycle and feeding habits.