No description available.

An evaluation was made of soil solarization to control Macrophomina phaseolina and Sclerotium rolfsii under the climatic conditions of the Sonoran Desert region of Arizona. Tarping of moist soil with clear polyethylene in the summer was most effective in raising soil temperatures, while tarping during the fall and spring were less efficient. In one summer trial, the maximum temperatures achieved were 7-8 C higher than control plots at 1, 15, and 30 cm depths. In none of the tests was the application of tarp effective in reducing M. phaseolina populations to non-detectable levels. After a six-week summer solarization treatment, S. rolfsii was controlled at the 15-cm but not the 30-cm depth. During a fall treatment control of S. rolfsii was achieved only at the 1-cm depth. After solarization, seeds of Euphorbia lathyris were planted in solarized and control plots. The incidence of M. phaseolina-associated mortality among seedlings planted in solarized plots was always the same as the control plot with the highest disease incidence. The utility of this technique may be limited by the heat tolerance of the target organisms. Studies of bacterial antagonists were initiated to determine their utility in enhancing pathogen control after the solarization treatment. Screening 43 bacterial isolates showed that seven of Pseudomonas fluorescens and one of Serratia marcescens exhibited some form of antagonism toward M. phaseolina, S. rolfsii and Verticillium dahliae in vitro. Antagonism was manifested as a complete inhibition of fungal development or reduced hyphal development coupled with suppression of sclerotial development. The action of the antagonists was found to be fungitoxic or fungistatic rather than fungicidal. None of the four P. fluorescens isolates tested were effective in preventing M. phaseolina infection of E. lathyris seedlings. The ability of these bacteria to prevent sclerotial formation while still permitting hyphal growth may be a useful technique for studying the two phases of the fungal life cycle separately.

Doctor of Philosophy / Department of Agronomy / Tesfaye Tesso / Fusarium stalk rot and charcoal rot caused by Fusarium thapsinum and Macrophomina phaseolina respectively are devastating global diseases in sorghum that lead to severe quality and yield loss each year. In this study, three sets of interrelated experiments were conducted that will potentially lead to the development of resistance based control option to these diseases. The first experiment was aimed at identifying sources of resistance to infection by M. phaseolina and F. thapsinum in a diverse panel of 300 sorghum genotypes. The genotypes were evaluated in three environments following artificial inoculation. Out of a total of 300 genotypes evaluated, 95 genotypes were found to have resistance to M. phaseolina and 77 to F. thapsinum of which 53 genotypes were resistant to both pathogens. In the second experiment, a set of 79,132 single nucleotide polymorphisms (SNPs) markers were used in an association study to identify genomic regions underlying stalk rot resistance using a multi-locus mixed model association mapping approach. We identified 14 loci associated with stalk rot and a set of candidate genes that appear to be involved in connected functions controlling plant defense response to stalk rot resistance. The associated SNPs accounted for 19-30% of phenotypic variation observed within and across environments. An analysis of associated allele frequencies within the major sorghum subpopulations revealed enrichment for resistant alleles in the durra and caudatum subpopulations compared with other subpopulations. The findings suggest a complicated molecular mechanism of resistance to stalk rots. The objective of the third experiment was to determine the functional relationship between stay-green trait, leaf dhurrin and soluble sugar levels and resistance to stalk rot diseases. Fourteen genotypic groups derived from a Tx642 × Tx7000 RIL population carrying combinations of stay-green quantitative trait loci were evaluated under three environments in four replications. The stg QTL had variable effects on stalk rot disease. Genotypes carrying stg1, stg3, stg1,3 and stg1,2,3,4 expressed good levels of resistance to M. phaseolina but the combination of stg1 and stg3 was required to express the same level of resistance to F. thapsinum. Other stg QTL blocks such as stg2 and stg4 did not have any impact on stalk rot resistance caused by both pathogens. There were no significant correlations between leaf dhurrin, soluble sugar concentration, and resistance to any of the pathogens.

Made available in DSpace on 2014-06-11T19:28:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-02-27Bitstream added on 2014-06-13T19:16:23Z : No. of bitstreams: 1 frigeri_t_me_jabo.pdf: 214550 bytes, checksum: a1c65c9e88fd5fc622a8f30d3f3a9e22 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O objetivo dessa pesquisa foi verificar a influência de Macrophomina phaseolina, Colletotrichum dematium f. truncata e Colletotrichum lindemuthianum na qualidade fisiológica de sementes de feijoeiro, em especial nos resultados do teste de condutividade elétrica. Foram utilizadas sementes das cultivares Carioca e FT Nobre. As sementes foram infectadas com os fungos em meio de cultura BDA sem e com restrição hídrica (acrescido de manitol a -1,0 MPa). Nos tratamentos testemunhas foram utilizados os mesmos meio de cultura, porém, sem a presença dos fungos. Para cada tratamento as sementes foram sobrepostas nos meios de cultura por 16 horas para M. phaseolina e por 48 horas para o caso de C. dematium f. truncata e C. lindemuthianum. Após secagem natural foram realizados testes de sanidade, germinação em areia e de vigor, como, índice de velocidade de emergência, peso da matéria seca da plântula, teste de frio, teste de envelhecimento acelerado e condutividade elétrica. Também foram realizadas análises na água de embebição das sementes no teste de condutividade elétrica, determinando-se as concentrações de potássio, cálcio e magnésio, assim como nos meios de cultura utilizados com e sem a sobreposição de sementes, para verificação da hipótese de consumo de nutrientes das sementes pelos fungos... / The aim of this research was to verify the influence of Macrophomina phaseolina, Colletotrichum dematium f. truncata and Colletotrichum lindemuthianum in the physiological quality of bean seeds, special in the results of electrical conductivity test. There were used seeds from Carioca and FT Nobre cultivars. The seeds were artificially inoculated with fungi M. phaseolina, C. dematium f. truncata and C. lindemuthianum in BDA medium culture with and without hydric restriction (it was added -1,0 MPa manitol). In the control treatment there was used the same medium culture without the presence of the fungi. For each treatment the seeds were placed on the medium culture for 16 hours for M. phaseolina and 48 hours for C. dematium f. truncata and C. lindemuthianum. After a nature dry, seeds were evaluated, by the blotter test, sand germination and vigor tests: speed of emergence index, seedlings dry weigh, cold, accelerated aging and electrical conductivity tests. Analyses from the imbibition water of the seeds in the electrical conductivity test, were also done a measuring of concentrations of potassium, calcium and magnesium, as well as in the medium culture used with and without the seeds, to verify the hypothesis of seeds nutrients consumption by the fungi...(Complete abstract, click electronic address below)

Made available in DSpace on 2014-06-11T19:28:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-05-15Bitstream added on 2014-06-13T20:58:17Z : No. of bitstreams: 1 rosa_j_me_jabo.pdf: 154567 bytes, checksum: 0d2897a42007e37a9a5f314b75f0f0f0 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) / Objetivou-se o ajuste de metodologia e seleção de genótipos de guandu para resistência a Macrophomina phaseolina a partir de material obtido pela Embrapa Pecuária Sudeste, e verificar o desenvolvimento micelial e esporulação do fungo em meios de cultura. O trabalho foi conduzido em casa de vegetação na UNESP/Jaboticabal no período de agosto de 2004 a dezembro de 2005. Para o ajuste de metodologia e seleção de genótipos resistentes ao fungo as sementes foram submetidas a escarificação com lixa d'água e inoculação artificial através do método de exposição das mesmas ao patógeno por diferentes períodos, que variaram de O a 72 horas. Foram avaliadas porcentagem de plantas sobreviventes e massa fresca. Já para o crescimento micelial e esporulação do fungo foi utilizado o método de sobreposição de discos de diferentes hospedeiros no meio de cultura. A escarificação das sementes contribuiu para a penetração do fungo nas mesmas o período de 24h de exposição das sementes ao fungo são suficientes para detectar diferenças no grau de resistência dos genótipos. Os genótipos mais resistentes são g167-97, g124-95, g27-94, g40-95, g154-95, g127-97 e g9m-97, e os mais suscetíveis são g48-95, g123-95, g8-95, g168-99 e g1m-95. A sobreposição de discos foliares de guandu em meio BDA e folha de papel de filtro em meio sojinha proporcionam um incremento na esporulação de M. phaseolina. / This work had the objective of determining the best schedule for artificial inoculation and select pigeon pea genotypes resistant to Macrophomina phaseolina in material obtained by Embrapa Pecuária Sudeste, and verify the mycelial growth and sporulation of the fungi in middle of culture. The work were carried in greenhouse at the UNESP/Jaboticabal, from August 2004 to December 2005. For the methodology and selection adjustment of resistant genotypes to the fungi the seeds were submitted scarified with water sandpaper and artificial inoculation the seeds were the contact method to fungi for different periods, which varied from O to 72 hours. They were evaluated percentage of surviving plants and fresh mass. For the mycelial growth and sporulation of the fungi was used the superposition of disks method of different hosts in the middle of culture. The scarified of the seeds contributed for penetration of the fungi at the seeds; the period of 24h of contact of the seeds to the fungi enough to detect differences in the resistance degree ofthe genotypes. The genotypes g167-97, g124-95, 927-94, g40-95, g154-95, g127-97 and g9m-97 were found to be the most resistant and most susceptible were g48-95, g123-95, g8-95, g168-99 and g1m-95. The treatment with superposition of the leaf disks of pigeon pea in BDA and disks of filter paper in middle of soybean extract were the treatments that provided better sporulation levei in the conditions of that experiment were half.

[ES] En la actualidad, el melón (Cucumis melo L.) es un cultivo con gran impacto económico mundial que se cultiva en más de 100 países. Su adaptación a diversas regiones en todo el mundo ha dado como resultado el gran polimorfismo actualmente observado en la especie. Esta variabilidad genética es un recurso imprescindible en los programas de mejora, pues constituye un reservorio valioso de nuevos alelos. La utilización de herramientas moleculares permite la optimización de los programas de mejora convencionales, consiguiendo el desarrollo de nuevas variedades más rápidamente y adaptándose así a las exigencias del productor y las preferencias del consumidor. El desarrollo de líneas de introgresión (ILs) mediante la ayuda de técnicas moleculares que facilitan el proceso de selección, constituye una estrategia óptima para la introducción de características favorables procedentes de tipos silvestres en cultivares comerciales. En la presente Tesis Doctoral se describe el desarrollo de una colección de ILs usando la entrada Queen's Pocket melon (del grupo Dudaim) de Irak, como parental exótico donante y el cultivar español 'Piel de Sapo' (del grupo Ibericus) como parental recurrente. Durante el proceso de generación de las ILs no sólo se tuvo en cuenta el genotipado (mediante diversas técnicas como HRM, la plataforma Agena Bioscience y GBS) para optimizar la recuperación del fondo genético recurrente, el número de introgresiones y la cobertura del genoma del parental donante, sino también el fenotipo mostrado por las diferentes familias. La selección final, formada por 16 ILs, presenta un promedio de 1,4 introgresiones por IL y representa el 62,6 % del genoma del parental donante. La caracterización fenotípica de esta colección de ILs permitió la identificación de 32 QTLs (Quantitative Trait Loci) estables en los dos ambientes evaluados. De éstos, 22 QTLs corresponden a caracteres morfológicos como peso, forma, reticulado, ancho de pulpa y cavidad; 9 QTLs están relacionados con características asociadas a maduración climatérica como la presencia de la capa de abscisión, aroma y firmeza de la pulpa; y uno se refiere al contenido de sólidos solubles. Muchos de los QTLs identificados en este trabajo no han sido descritos anteriormente, lo cual constituye un valioso recurso tanto de alelos nuevos potencialmente interesantes en mejora como para el estudio de las regiones genómicas y genes implicados en el control de ciertos caracteres de interés agronómico. Por otra parte, otros QTLs confirmaron regiones previamente descritas por otros autores. En esta Tesis se describen líneas potencialmente interesantes en cuanto a presencia de aroma, tamaño reducido del fruto y/o formas más redondeadas, características buscadas en el mercado de tipos 'Piel de Sapo'. La caracterización de ese conjunto de ILs también se llevó a cabo para la resistencia a un hongo patógeno del suelo, Macrophomina phaseolina. A pesar de la moderada resistencia descrita en trabajos anteriores para el parental Dudaim, ninguna línea resultó resistente. El estudio que se presenta en esta Tesis acerca de la influencia de la temperatura en la patogenicidad de este hongo ha demostrado que la resistencia del parental es superada con temperaturas altas y por tanto, no es estable. En este cribado, tan sólo una entrada silvestre africana resultó resistente a temperaturas altas. De igual manera se realizó un ensayo de tolerancia a los hongos del suelo Monosporascus cannonballus y M. eutypoides, principales responsables del colapso del melón, que causa también muchas pérdidas económicas. Los resultados permitieron concluir que M. cannonballus presenta mayor patogenocidad que M. eutypoides y que la temperatura también afecta de forma importante a la severidad de los síntomas, apoyando estudios previos. Las dos entradas africanas y de la India que presentaron mayor tolerancia a Monosporascus spp. pueden ser de interés en futu / [CAT] A l'actualitat, el meló (Cucumis melo L.) és un conreu amb gran impacte econòmic que es cultiva en més de 100 països. La seua adaptació a diverses regions per tor el món ha donat com a resultat el gran polimorfisme que actualment observem en l'espècie. Esta variabilitat genètica és un recurs imprescindible en els programes de millora, ja que constitueix un reservori valuós de nous al¿lels. La utilització de ferramentes moleculars permet l'optimització dels programes de millora convencionals, aconseguint el desenvolupament de noves varietats més ràpidament i adaptant-se així a les exigències del productor i les preferències del consumidor. El desenvolupament de línies d'introgressió (ILs) mitjançant l'ajuda de tècniques moleculars que faciliten el procés de selecció, constitueix una estratègia òptima per a la introducció de característiques favorables vinents de tipus silvestres en cultivars comercials. En la present Tesi Doctoral es descriu el desenvolupament d'una col¿lecció d'ILs usant l'entrada Queen's Pocket melon (grup Dudaim) d'Iraq, com a parental exòtic donant i el cultivar espanyol 'Piel de Sapo' (grup Ibericus) com a parental recurrent. Durant el procés de generació de les ILs no solament es tingué en compte el genotipatge (mitjançant diverses tècniques com HRM, la plataforma Agena Bioscience i GBS) per a optimitzar la recuperació del fons genètic recurrent, el nombre d'introgressions i la cobertura del genoma del parental donant, sinó també el fenotip mostrat per les diferents famílies. La selecció final, formada per 16 ILs, presenta una mitjana de 1,4 introgressions per IL i representa el 62,6% del genoma del parental donant. La caracterització fenotípica d'aquesta col¿lecció d'ILs permeté la identificació de 32 QTLs (Quantitative Trait Loci) estables en els dos ambients avaluats. D¿aquests, 22 QTLs corresponen a caràcters morfològics com pes, forma, reticulat, amplària de polpa i cavitat; 9 QTLs estan relacionats amb característiques associades a maduració climatèrica com la presència de la capa d'abscissió, aroma i fermesa de la polpa; i un es refereix al contingut de sòlids solubles. Molts dels QTLs identificats en este treball no han sigut descrits anteriorment, cosa que constitueix un valuós recurs tant d¿al¿lels nous potencialment interessants en millora com per a l¿estudi de les regions genòmiques i gens implicats en el control de certs caràcters d'interés agronòmic. Per una altra banda, altres QTLs confirmaren regions prèviament descrites per altres autors. En esta Tesi es descriuen ILs potencialment interessants respecte a la presència d¿aroma, mesura reduïda del fruit, i/o formes més arrodonides, característiques buscades en el mercat de tipus 'Piel de Sapo'. La caracterització d¿aquesta col¿lecció d'ILs també es va dur a terme per a la resistència a un fong patogen del sòl, Macrophomina phaseolina. Malgrat la moderada resistència descrita en treballs anteriors per al parental Dudaim, cap línia resultà resistent. L'estudi que es presenta en aquesta Tesi sobre la influència de la temperatura en la patogenicitat d'aquest fong ha demostrat que la resistència del parental es superada amb temperatures altes i per tant, no és estable. En aquest estudi, tan sols una entrada silvestre africana resultà resistent a temperatures altes. També es va realitzar un assaig de tolerància als fongs del sòl Monosporascus cannonballus i M. eutypoides, principals responsables del col¿lapse del meló, que causa també moltes pèrdues econòmiques. Els resultats permeteren concloure que M. cannonballus presenta major patogenicitat que M. eutypoides i que la temperatura també afecta de forma important a la severitat dels símptomes, recolzant estudis previs. Les dues entrades africanes i la hindú que presentaren major tolerància a Monosporascus spp. poden ser d'interés en futurs programes de millora. / [EN] Nowadays, the melon (Cucumis melo L.) is a crop with great economic impact worldwide that is grown in more than 100 countries. Its adaptation to diverse regions around the world has turned out in the high polymorphism this species shows. This genetic variability is an indispensable resource for breeding programs, since it is a valuable reservoir of new alleles. The use of molecular tools allows the optimization of conventional breeding programs, achieving the development of new varieties more quickly and adapting to the demands of the producer and to consumer preferences. The development of Introgression Lines (ILs) employing molecular techniques to assist in the selection process, constitutes an optimal strategy for the introduction of favourable traits from wild types in commercial cultivars. In this PhD thesis the development of an ILs collection is described, using the Queen's Pocket melon accession (Dudaim group) of Irak as the exotic donor parental and the Spanish cultivar 'Piel de Sapo' (Ibericus group) as the recurrent parental. During the ILs generation process, not only genotyping was taken into consideration (several techniques such as HRM, the Agena Bioscience platform and GBS were used) to optimize the recovery of the recurrent genetic background, the number of introgressions and the coverage of the donor genome, but also the phenotype shown by the different families. A set of 16 ILs was finally selected, bearing an average of 1.4 introgressions per IL and representing 62.6% of the donor genome. The phenotypic characterization of this IL collection allowed the identification of 32 stable QTLs (Quantitative Trait Loci) in the two environments evaluated. Out of these, 22 QTLs correspond to morphological traits such as weight, shape, netting, flesh width and cavity; 9 QTLs are related to traits associated with the climacteric ripening such as the presence of the abscission layer, aroma and flesh firmness; and one related to the soluble solids content. Many QTLs identified in this work have not been described previously. This implies new alleles of potential interest not only in breeding but also in the study of new genomic regions and genes controlling agronomical and quality traits. On the other hand, other QTLs confirmed regions previously described by other authors. In this work, interesting lines are described in terms of the presence of aroma, reduction of fruit size and / or more rounded shapes, characteristics requested by 'Piel de Sapo' consumers. The phenotyping of this set of ILs was also carried out for searching for resistance to a pathogenic soil fungus, Macrophomina Phaseolina. Despite the moderate resistance described for the Dudaim parental in a previous work, no line was resistant. The study presented herein about the influence of temperature on the pathogenicity of this fungus, has shown that the resistance of the donor parenal is overcome with the temperature increase and therefore, is not stable. In this screening, only one African wild accession was resistant to high temperatures. In addition, an assay searching for tolerance to the fungi of the soil, Monosporascus cannonballus and M. eutypoides, the main responsible for melon collapse, was carried out. The results allowed us to conclude that M. cannonballus presents higher pathogenicity than M. eutypoides. Additionally, temperature also affected the symptoms severity, which is coherent with previous studies. Two African and one Indian accessions were the ones displaying higher tolerance to Monosporascus spp. They may be of great interest in future melon breeding programs. / Castro Alcocer, GE. (2019). APROVECHAMIENTO DE HERRAMIENTAS GENETICAS Y GENOMICAS PARA DESARROLLO DE NUEVAS POBLACIONES PARA LA MEJORA DEL MELON POR RESISTENCIA A PATÓGENOS Y CALIDAD [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/131206 / TESIS

Submitted by Helena Bejio (helena.bejio@unioeste.br) on 2017-11-23T17:51:39Z No. of bitstreams: 2 Eloisa Lorenzetti 2017.pdf: 1638897 bytes, checksum: 37d0d636adf093d3df43c201d58eeb5b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-11-23T17:51:39Z (GMT). No. of bitstreams: 2 Eloisa Lorenzetti 2017.pdf: 1638897 bytes, checksum: 37d0d636adf093d3df43c201d58eeb5b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-02-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Several works using extracts obtained from medicinal plants have demonstrated direct and potential antimicrobial action to induce the accumulation of secondary metabolites, which are very important as plant defense mechanisms against pathogens. The objective of this work was to develop an alternative method using rosemary extract (Rosmarinus officinalis L.) at concentrations 0%, 1%, 2.5% and 5%, to verify the antimicrobial activity against Macrophomina phaseolina, control of charcoal rot in soybean stem and determine the activity of peroxidase, polyphenol oxidase, phenylalanine ammonia-lyase (PAL) and protein content on soybean plants. We performed in vitro assays in order to analyze mycelial growth of the fungus, fungus mass and number of micro-sclerotia, greenhouse tests to evaluate the area under the disease progress curve (AUDPC), and biochemical analyzes to verify a possible induction of resistance in the treated plants. For the determination of the defense enzymes, soybean plants were treated with the extracts and inoculated with M. phaseolina. Samples were collected at 0, 36, 72, 120, 168, 216 and 264 h after treatment. The rosemary extract reduced by 44% and 74% the fungal growth on solid and liquid media, respectively, while for the micro-sclerotia the reduction was of 61%. For the AUDPC in the first and in second assays, there were a reduction of 53% and 56% respectively in the disease. For the samples collected at the base of steam, peroxidase had the highest concentrations of the extract with two peaks of induction. The polyphenol oxidase activity increased from 36 to 120 hours after treatment with extract at 5%. PAL activity was induced only with 5% extract, with increases 83% and 130% higher in times 168 and 216 hours after treatment, respectively. For enzymes activities in root, peroxidase again showed two peaks for increase at 5% concentration, polyphenol oxidase was 426% higher at 216 hours after treatment and PAL showed an increase of 340% at 216 hours after treatment with 5% extract. These results indicate potential of rosemary extract in the control of charcoal rot in soybean and in the induction of plant defense enzymes in soybean. / Diversos trabalhos utilizando extratos obtidos de plantas medicinais têm demonstrado ação antimicrobiana direta e potencial de induzir o acúmulo de metabólitos secundários, sendo estes muito importantes nos principais mecanismos de defesa das plantas aos patógenos. O objetivo deste trabalho foi desenvolver um método alternativo através da utilização do extrato de alecrim (Rosmarinus officinalis L.), nas concentrações 0%, 1%, 2,5% e 5%, para verificar a atividade antimicrobiana contra Macrophomina phaseolina, controlar a podridão cinzenta da haste em soja e determinar as atividades de peroxidase, polifenoloxidase, fenilalanina amônia-liase e teor de proteína de plantas de soja tratadas. Foram realizados ensaios in vitro a fim de analisar o crescimento micelial do fungo, a massa do fungo e o número de microescleródios, ensaios in vivo em casa de vegetação para avaliar a área abaixo da curva de progresso da doença (AACPD), além de análises bioquímicas para verificar uma possível indução de resistência nas plantas tratadas. Para determinação das enzimas de defesa, plantas de soja foram tratadas com os extratos e inoculadas com M. phaseolina, sendo retiradas amostras para análise nos tempos 0, 36, 72, 120, 168, 216 e 264 h após o tratamento. O extrato de alecrim reduziu em até 44% e 74% o crescimento fúngico em meios sólido e líquido, respectivamente, enquanto que para micro-escleródios a redução foi de 61%. Para AACPD, no primeiro e no segundo ensaios houve redução de 53% e 56% respectivamente. Nas amostras retiradas do colo das plantas, para peroxidase, as concentrações mais elevadas do extrato proporcionaram dois picos de indução. Houve constante incremento na atividade de polifenoloxidase desde 36 até 120 h após o tratamento para a concentração 5% do extrato de alecrim. Para FAL apenas a concentração 5% promoveu incremento 83% e 130% maior nos tempos 168 e 216 h após o tratamento, respectivamente. Para as atividades na raiz, a peroxidase novamente apresentou dois picos de incremento para a concentração 5% do extrato, a polifenoloxidase foi 426% maior na concentração 5% às 216 h após o tratamento e a atividade de FAL apresentou incremento de 340% no tempo 216 h após o tratamento com 5% do extrato. Estes resultados indicam potencial do extrato de alecrim no controle de podridão cinzenta da haste em soja e na indução da atividade de enzimas de defesa em colo e raiz de soja.

The production of strawberries can be severely limited by soilborne plant pathogens, insects and weeds. Macrophomina phaseolina is a problematic soilborne fungal pathogen in California strawberry production inciting the disease Macrophomina crown rot. When established, the pathogen can cause extensive plant decline and mortality. Host resistance will be a critical tool for managing this disease and guiding breeding programs in the post methyl bromide era. Evaluation of host resistance in strawberry germplasm to M. phaseolina was evaluated through phenotypic assessments of disease incidence. A total of 90 strawberry cultivars and elite selections were included in a replicated field trial conducted in artificially inoculated soils to assess host resistance. Significant differences in levels of resistance and susceptibility were observed among genotypes tested in this trial. The five most resistant strawberry genotypes from highest to lowest in percent plant mortality were: UC-R, UC-G, UC-V, Manresa, and Osceola. The five most susceptible strawberry genotypes with the highest percent mortality in ranking order from highest to lowest were: UC-J, Ruby June, Festival, UC-Y, and UC-A. Of the genotypes tested in this trial UC-V, Manresa and Osceola could be characterized as highly resistant, but no complete resistance was observed. An additional study was conducted to correlate host symptom expression with the extent of pathogen colonization in different strawberry tissues, and to determine if resistant germplasm can contribute to secondary inoculum production in the field. An established qPCR method was utilized to quantify M. phaseolina colonization of strawberry tissues. There were significant effects for cultivar (P < 0.0001) as well as a significant two-way interaction of cultivar x sample time (P= 0.0083) on the concentration of M. phaseolina DNA detected in strawberry tissues. Expression of the resistant phenotype in strawberry cultivars was associated with limited plant colonization by M. phaseolina. The extent of colonization of a specific cultivar by M. phaseolina was dependent on the sample time after inoculation with the pathogen. In addition, the roots and crowns of a specific strawberry cultivar were equally colonized on a per plant tissue weight basis, but this provides only speculation into the mechanisms conferring host resistance. A third study was conducted to integrate host resistance of strawberry genotypes with the use of organic amendments in effort to mutually enhance the efficacy of each factor for the control of Macrophomina crown rot. Artificially inoculated potting substrate was amended with Brassica juncea mustard seed meal at a rate of 4.94 tons ha-1(MSM), and anaerobic soil disinfestation utilizing rice bran at a rate of 22.24 tons ha-1 (ASD) were compared to a non-amended (UTC) and steam controls. The soil assay indicated that the ASD and steam treatments were able to reduce the CFU g-1 potting substrate of M. phaseolina by 99.7-100%. In addition, there were significant effects of soil treatment on the fresh biomass of weed seedlings recovered from the potting substrate. However, disease severity and host colonization of multiple strawberry cultivars by M. phaseolina was not reduced when grown in the treated potting substrate. The effect of strawberry cultivar on the extent of pathogen colonization was highly significant (P < 0.0001), in which cultivars characterized as resistant from phenotypic screenings possessed lower concentrations of M. phaseolina DNA. The suppression of M. phaseolina in response to organic amendments was limited but this study supports findings from previous experiments that genotype specific host resistance minimizes host colonization and reduces the production of secondary inoculum.

MSCAGR (Plant Production) / Department of Plant Production / See the attached abstract below

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-05-03T18:31:57Z No. of bitstreams: 1 ANDRESSA LACERDA NÓBREGA UGULINO - DISSERTAÇÃO PPGSA ACADÊMICO 2017..pdf: 676544 bytes, checksum: 0dd2e41c1011a60929ca0702449f6287 (MD5) / Made available in DSpace on 2018-05-03T18:31:57Z (GMT). No. of bitstreams: 1 ANDRESSA LACERDA NÓBREGA UGULINO - DISSERTAÇÃO PPGSA ACADÊMICO 2017..pdf: 676544 bytes, checksum: 0dd2e41c1011a60929ca0702449f6287 (MD5) Previous issue date: 2017 / O fungo Macrophomina phaseolina (Tassi.). Goid é o agente etiológico de uma das principais doenças na cultura do feijão-caupi, vulgarmente conhecida como podridão cinzenta do caule. Em decorrência da falta de produtos fitossanitários registrados para o controle desta doença um aumento na busca por métodos de controle alternativo é cada vez mais comum. O objetivo do presente trabalho foi avaliar o efeito de óleos essenciais sobre o crescimento micelial do fungo M. phaseolina. Os óleos testados foram de hortelã (Mentha sp.), eucalipto (Eucalyptus spp.), copaíba ( Copaifera sp.) e alecrim-da-chapada (Lippia gracilis), nas concentrações 0,4; 0,6; 0,8 e 1,0%. Os óleos foram incorporados ao meio de cultura do tipo BDA e posteriormente vertidos em placas de Petri de 90x15mm, após a solidificação do meio, discos de 8mm contendo o micélio do patógeno foram repicados para as placas com os respectivos tratamentos. O experimento foi conduzido no delineamento experimental inteiramente casualizado (DIC) em arranjo fatorial 4 x 4 + 1 +1, sendo dezesseis tratamentos mais uma testemunha negativa e uma testemunha positiva que constou da aplicação suplementar no meio (BDA) do fungicida Sportak 450 EC (Procloraz), e cinco repetições, totalizando 90 parcelas experimentais. Posteriormente todas as placas foram transferidas para incubadora do tipo B.O.D. (biochemical oxygen demand) a 27 ± 2 ºC. Foram realizadas medições diárias do diâmetro da colônia em dois sentidos perpendiculares até que tomasse toda a superfície do meio de cultura de uma das placas. Os dados obtidos foram interpretados por meio de análise de variância não paramétrica e as médias foram comparadas pelo teste de Kruskal-wallis, a 5% de probabilidade de erro e Scott Knott a 5% de probabilidade nos casos em que existiram diferenças significativas e normalidade dos dados. Os óleos essenciais de hortelã e alecrimda-chapada apresentaram melhores resultados quanto a inibição do crescimento micelial, enquanto que os óleos de eucalipto e copaíba apesar de potencialmente promissores, apresentaram inibição intermediária do crescimento micelial do fungo. / Macrophomina phaseolina (Tassi.). Goid is the etiological agent of one of the major diseases in cowpea bean crop, commonly known as gray rot stem. Due to the lack of registered phytosanitary products to control this disease, the search for alternative control methods is increasingly common. The objective of this study was to evaluate the effect of essential oils on the mycelial growth of M. phaseolina. The oils tested were Mentha sp.,Eucalyptus spp., Copaifera sp., and Lippia gracilis at concentrations of 0.4; 0.6; 0.8 and 1.0%. The work was conducted in Phytopathology Laboratory of the Federal University of Campina Grande. Daily measurements of the colony diameter were performed in two perpendicular directions until it filled the entire surface of the culture medium of one of the plates. The experiment was conducted in a completely randomized experimental design in a factorial arrangement 4 x 4 + 1+1, with sixteen treatments plus one negative control and one positive control, which consisted of the supplemental application in the medium (BDA) of the fungicide Sportak 450 EC (Procloraz), and five replications, totaling 90 experimental plots. The data were interpreted through non-parametric analysis of variance and the means were compared by the Kruskal-wallis test, with a 5% probability of error and Scott Knott at 5% probability in cases where there were significant differences and data normality. The Mentha sp. essential oil and Lippia gracilis showed better results in inhibiting mycelial growth, while the Eucalyptus essential oil and Copaifera, although potentially promising, showed intermediate inhibition of fungal mycelial growth.