Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-06-09T21:01:25Z No. of bitstreams: 1 2012 - Diene Elen Miranda da Silva.pdf: 765816 bytes, checksum: c629b2854d2d66a38d8aa7de0bccb71b (MD5) / Made available in DSpace on 2017-06-09T21:01:25Z (GMT). No. of bitstreams: 1 2012 - Diene Elen Miranda da Silva.pdf: 765816 bytes, checksum: c629b2854d2d66a38d8aa7de0bccb71b (MD5) Previous issue date: 2012-08-17 / CAPES / The incidence of rust occurs on nursery seedlings and plants in the field, this disease caused by of Puccinia psidii is the most severe on Eucalyptus tree. The objective of this work is to quantify the partial resistance of ten species of Eucaliptus: E. propinqua, E. citriodora, E. grandis, E. urophylla, E. microcorys, E. urograndis, E. robusta, E. saligna, E. dunni and E. phaeotricha to eucalypt rust. For it some experiments were performed in greenhouse of Department of Entomology and Plant Pathology of UFRRJ. Were used 200 eucalypt seedlings of 3 months old obtained from seeds. The experimental design was totally randomized, with 10 treatments and 10 repetitions, with 1 plant to each repetition. The inoculation was performed by atomization of leaves with suspension of urediniospores in the concentration of 2x 104 spores/mL, obtained from fresh pustules. Later the seedlings were incubated in wet chamber in the dark by 48 hours. The parameters of resistance evaluated were: number of pustules by leaflet, severity, average latent period, AUDPC (area under the disease progress curve). The data otained were transformed too 0,5 and ?and submitted to ANOVA and mean comparison by Scott-Knott test at 5% probability, using the software SAEG. Meaningful differences were found among the eucalypt species for the parameters studied. The species E. urograndis showed a lower average number of pustules per leaflet, lower severity, greater mean latent period and small values of AUDPC (area under the disease progress curve), thus showing greater partial resistance to the rust. / A incid?ncia da ferrugem ocorre em mudas de viveiro e em plantas jovens no campo, essa doen?a causada por Puccinia psidii ? uma das mais severas do eucalipto. O presente trabalho teve como objetivo quantificar a resist?ncia parcial de dez esp?cies de Eucaliptus: E. propinqua, E. citriodora, E. grandis, E. urophylla, E. microcorys, E. urograndis, E. robusta, E. saligna, E. dunni e E. phaeotricha ? ferrugem do eucalipto. Para isso foram conduzidos dois experimentos em casa de vegeta??o no Departamento de Entomologia e Fitopatologia da UFRRJ. Foram utilizadas 200 mudas de eucalipto com tr?s meses de idade, obtidas a partir de sementes. O delineamento experimental utilizado foi inteiramente casualizado, com dez tratamentos e dez repeti??es, sendo uma planta por repeti??o. A inocula??o foi realizada por meio da atomiza??o de folhas com suspens?o de uredosporos na concentra??o de 2x104 esporos/mL, obtidos a partir de p?stulas frescas. Em seguida, as mudas foram incubadas em c?mara ?mida e escura por 48h. Foram avaliados os par?metros de resist?ncia: n?mero m?dio de p?stulas por fol?olo, severidade, per?odo latente m?dio e AACPD. Os dados obtidos foram transformados em 0,5 e ?100, e submetidos ? an?lise de vari?ncia e ? compara??o de m?dias pelo teste de Scott-Knott ao n?vel de 5% de probabilidade, por meio do software SAEG. Foram encontradas diferen?as significativas entre as esp?cies de eucalipto para os par?metros estudados. A esp?cie E. urograndis apresentou um menor n?mero m?dio de p?stulas por fol?olo, menor severidade, maior per?odo latente m?dio e valores menores da ?rea abaixo da curva do progresso da doen?a, tendo dessa forma maior resist?ncia parcial ? ferrugem.

Master of Science / Department of Plant Pathology / Karen A. Garrett / While plants are typically exposed to multiple stressors in the field, studies of genome-wide gene expression and phytohormone responses in wild plant species exposed to multiple stressors are rare. Our objectives were to determine the effects of drought and rust stress on gene expression in Andropogon gerardii, the dominant grass in tallgrass prairie, and associated levels of phytohormone production. In a factorial design, plants experiencing drought or non-drought conditions were either inoculated with the rust pathogen Puccinia andropogonis or not inoculated. Gene expression was evaluated with maize microarrays. Drought-stressed plants significantly decreased expression of genes associated with photosynthesis and the hypersensitive response, while expression of genes associated with chaperones and heat-shock proteins increased. No significant differences in gene expression in response to the rust treatment were detected using a mixed model analysis of variance and false discovery rate protection, probably because of the low infection rate. Phytohormone production increased when both stresses were present. The rust treatment significantly increased benzoic acid (BA) production in the presence of drought, while the drought treatment alone significantly increased salicylic acid (SA) production. Leaf tips usually had higher levels of all phytohormones in all treatments and the leaf section evaluated had a larger effect on phytohormone level than did the treatments applied.

Leaf rust and stripe rust of wheat (Triticum aestivum L.) are caused by the fungal pathogens Puccinia triticina, and Puccinia striiformis f.sp. tritici, respectively. In North America, the incorporation of adult-plant resistance (APR) genes into breeding lines has been an important strategy to achieve durable resistance to both diseases. Previously, the spring wheat cultivar AC Domain was reported to express an effective level of adult-plant resistance (APR) to leaf rust under field conditions. Early gene postulation work had suggested AC Domain might carry the APR gene Lr34 due to its phenotypic similarity to other Lr34 carrying lines. However, new gene specific markers have shown that AC Domain is not a carrier of Lr34. The objective of this research was to genetically localize the resistance in AC Domain, which is important because the cultivar has frequently been used as a parent in Canadian breeding programs, primarily for its value as a source of pre-harvest sprouting resistance. A mapping population of 185 doubled haploid (DH) lines derived from the cross ‘RL4452’ by ‘AC Domain’ was used for this study. RL4452 is a known carrier of Lr34. During 2011-2012, the DH population was evaluated in field leaf rust nurseries at Saskatoon, SK and Portage, MB and at a stripe rust nursery at Lethbridge, AB. Field results indicated that rust resistance in the mapping population was variable, with lines ranging from highly resistant, to highly susceptible. DH lines carrying Lr34 showed a high level of resistance to both diseases. Thus, the non-Lr34 carriers were genotyped using select SSR markers, and by an Illumina 9k Infinium iSelect SNP assay for subsequent quantitative trait loci (QTL) analysis. QTL analysis revealed that AC Domain donated a major resistance QTL located on chromosome 2BS, that mapped 46 cM proximal to markers linked to Lr16, and explained a significant portion of the leaf and stripe rust phenotypic variance in all test environments. In addition, this QTL was significantly associated with the expression leaf tip necrosis (LTN), reduction in area under the disease progress curve (AUDPC), and coefficient of infection (CI). In certain environments the interaction between the 2B QTL and Lr34 was additive resulting in a superior level of rust resistance. Indoor rust testing showed AC Domain was susceptible to both diseases at the seedling stage. Taken together these results suggest that the identified resistance in AC Domain is likely due to the presence of an APR gene, on chromosome 2BS.

Thesis (MSc (Genetics))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Microsatellites were used to differentiate Leaf (Puccinia triticina Eriks.) and Yellow rust (Puccinia striiformis Westend. f. sp. tritici Eriks.) pathotypes. There was sufficient diversity in the Leaf rust microsatellite markers to differentiate the pathotypes and create a phylogenetic tree of Leaf rust. Three of the microsatellite markers were sufficient to differentiate all the Leaf rust pathotypes. Sufficient diversity in the Yellow rust microsatellite markers was also observed which made it possible to differentiate the pathotypes. Only three pathotypes were used so no phylogenetic inference was made. Two microsatellite markers were sufficient to differentiate all the yellow rust pathotypes. Microsatellite and Amplified Fragment Length Polymorphisms (AFLP) markers were used to differentiate Stem rust (Puccinia graminis f. sp. tritici Eriks. and Henn.) pathotypes, and the data was combined for phylogenetic analysis. AFLP bands unique to each Stem rust pathotype were converted to Sequence Characterised Amplified Region (SCAR) markers. A single specific SCAR marker was created for UVPgt52. A second SCAR marker amplified four of the eight pathotypes. None of the other SCAR markers were specific. A 270 basepair fragment of the ITS1 region of the rDNA gene of all the Puccinia spp. was also sequenced in order to develop pathotype specific primers that could be used in a Real Time-PCR to determine relative levels of pathogen inoculum in a sample. Unfortunately insufficient diversity in the sequences of the ITS1 region of the rDNA gene did not allow unique primers to be designed for each pathotype making it impossible to proceed with the relative quantification using Real Time-PCR. Following marker development ninety one field isolates were collected from eleven sites in the Overberg and Swartland regions during 2008 and 2009. In the field isolates, four different Leaf rust pathotypes were identifiable. UVPgt13 and UVPgt10 were most prevalent. The most prevalent Stem rust pathotypes were UVPgt50, UVPgt52, UVPgt54 and UVPgt57. Only 6E16A- was identifiable in the Yellow rust isolates. There were no apparent patterns in the distribution of Leaf, Stem or Yellow rust. Leaf and Stem rust were widely distributed, while Yellow rust was confined to three sites in the central South Cape, the only sites where climatic conditions were favourable for its development during the sampling period. The low levels of diversity found in the rust population when compared to international populations are probably due to the relatively small population size, the lack of a host for sexual reproduction, the small sample size, the effective monoculture and the strong selective pressure created by artificial control methods. / AFRIKAANSE OPSOMMING: Mikrosatellietmerkers is gebruik om Blaar- (Puccinia triticina Eriks.) en Geelroes-( Puccinia striiformis Westend. f. sp. tritici Eriks.) patotipes te onderskei. Daar was genoeg diversiteit in die Blaarroesmerkers om verskillende patotipes te kon onderskei en om „n filogenetiese-boom te kon saamstel. Met drie van die mikrosatellietmerkers was dit moontlik om al die Blaarroespatotipes te kon onderskei. Daar was genoeg diversiteit in die Geelroesmerkers om al die patotipes te kon skei en met twee van die mikrosatellietmerkers kon al drie Geelroespatotipes van mekaar onderskei word. Mikrosatelliet- en ge-Amplifiseerde-Fragment-Lengte-Polimorfismes (AFLP) is gebruik om die Stamroes- (Puccinia graminis f. sp. tritici Eriks. and Henn.) patotipes te skei. AFLP-fragmente uniek aan „n spesifieke patotipe is omgeskakel na Volgorde-Spesifieke-ge-Amplifiseerde-Streek (SCAR) merkers. „n Spesifieke SCAR-merker is gemaak vir UVPgt52. „n Tweede SCAR-merker het vier van die patotipes geidentifiseer. Nie een van die ander SCAR-merkers was spesifiek t.o.v. „n spesifieke patotipe nie. Die volgorde van „n 270 basispaar fragment van die ITS1-streek van die rDNS-geen van al die Puccinia spp. is bepaal om patotipe spesifieke inleiers te kon ontwerp. Hierdie inleiers kan gebruik word om „n Intydse-Polimerase-Ketting-Reaksie (RT-PCR) te ontwerp om sodoende die relatiewe vlakke van die patogeen besmetting in „n monster te bepaal. Daar was nie genoeg diversiteit in die bepaalde volgordes om die spes1fieke inleiers te kon identifiseer nie en dus is RT-PCR laat vaar. Na die ontwikkeling van die merkers was een-en-negentig veldmonsters ingesamel afkomstig van elf lokaliteite in die Overberg en Swartland gedurende 2008 en 2009. Vier Blaarroespatotipes was uitkenbaar. Blaarroespatotipes UVPrt10 en UVPrt13 was die mees algemeenste. UVPgt50, UVPgt52, UVPgt54 en UVPgt57 was die mees algemene Stamroespatotipes. Net 6E16A- is geidentifiseer by die Geelroes-isolate. Daar was geen patroon in die verspreiding van Blaar-, Stam- of Geelroes patotipes. Blaar- en Stamroes was die wydste versprei, maar Geelroes het net by drie lokale in die sentrale Suid-Kaap voorgekom. Die lokaliteite is die enigste waar die weersomstandighede gunstig was vir Geelroes ontwikkeling gedurende die periode van monsterneming. Die lae vlakke van diversiteit wat in die roespopulasie gevind was is in teenstelling met internasionale populasies. Dit mag moontlik wees as gevolg van die relatief beperkte populasie grootte, die afwesigheid van „n gasheer vir seksuele voortplanting, die beperkte hoeveelheid monsters wat ingesamel is en die sterk selektiewe druk weens kunsmatige beheer.

Made available in DSpace on 2016-12-08T16:44:38Z (GMT). No. of bitstreams: 1 PGPV08MA069.pdf: 749700 bytes, checksum: 8827df9f189a59df731fb6cc3e561047 (MD5) Previous issue date: 2008-03-06 / The white oat (Avena sativa L.) is a winter cereal adapted different regions, used in the production of grains, green grass, hay, silage and mutch soil coverage in the winter. The leaf rust and helminthosporium are considered frequent diseases in oats. The damages are due to the reduction of the plant green area photosynthesis. This report aimed to obtain equations of damage function to multiple pathosystem involving leaf rust and helminthosporiosis in two white oat cultivars and correlate the disease intensity with the yield components. The experiments were performed in the Center of Agroveterinarian Sciences, Santa Catarina State University, Lages, SC experimental area, in the 2006 and 2007 agricultural harvest. The leaf diseases degree was generated through the use of increasing doses and number of applications (one, two and four) of pyraclostrobina + epoxiconazole (33.25 +12.5, 49.87 +18.75, 66.5 +25 g ai ha-1) fungicide in UPFA 20 Teixeirinha and UPFA 22 Temprana cultivars. The experimental units consisted of five lines of sowing, spaced at 0.20 m and five meters in length. Were analyzed the following variables: leaf incidence and severity, grain yield, a thousand grain mass and hectoliter weight. The disease evaluations were performed every 10 days pulling up randomly 10 plants per plot. Generally the helminthosporiosis was the prevalent disease in both agricultural harvest and oat cultivars until the flowering beginning. The leaf rust had its intensity increased in subsequent stages. In the first part of this study was attempted to determine the equations of damage function by the regression analysis between disease intensity and grain yield for each plant development stage. Significant equations were obtained for the UPFA 20 and UPFA 22 cultivars in both agricultural harvests, where through them was possible to calculate the Economic Damage Threshold (EDT) by phonological stage of culture. In its second part, the leaf incidence and severity values were submitted to the Area Under the Disease Progress Curve (AUDPC), which were correlated with the grain yield, thousand grain mass and hectoliter weight. There were negative and significant correlations from the AUDPC with grain yield, thousand grain mass and hectoliter weight in both growing season. From these values it was achieved that as higher is the leaf diseases intensity highest are the AUDPC values, resulting in the decrease of productive variables values. With values of grain yield, thousand grain mass and hectoliter weight the third work purpose quantify the economic damage treschold and control percentage of these two diseases according to the number and dose of fungicide application. The damage to the grain yield, thousand grains mass and hectoliter weight were higher in the 2007 harvest for both cultivars. The leaf diseases control percentage was higher in both cultivars in the 2007 harvest, reaching based on the leaf severity 86.74 % and 85.90 % respectively for UPFA 20 and UPFA 22 / A aveia branca (Avena sativa L.) é um cereal de estação fria adaptado a diferentes regiões, usada na produção de grãos, forragem verde, feno, silagem, e cobertura verde/morta de solo no inverno. A ferrugem da folha e a helmintosporiose são consideradas doenças freqüentes em aveia. Os danos causados são atribuídos à redução da área foliar fotossintetizante ativa da planta. O objetivo deste trabalho foi obter equações da função de dano para patossistema múltiplo envolvendo ferrugem da folha e helmintosporiose em duas cultivares de aveia branca e correlacionar a intensidade das doenças com componentes do rendimento. Os experimentos foram conduzidos na área experimental do Centro de Ciências Agroveterinárias, Lages, SC, nas safras agrícolas de 2006 e 2007. O gradiente das doenças foliares foi gerado pelo uso de doses crescentes e número de aplicações (uma, duas e quatro) do fungicida piraclostrobina + epoxiconazole (33,25+12,5, 49,87+18,75, 66,5+25 g de i.a. ha- 1) nas cultivares UPFA 20 Teixeirinha e UPFA 22 Temprana. As unidades experimentais constaram de cinco linhas de semeadura, espaçadas em 0,20 m, com cinco metros de comprimento. Analisaram-se as seguintes variáveis: incidência e severidade foliar, rendimento de grãos, massa de mil grãos e peso do hectolitro. As avaliações de doença foram realizadas a cada 10 dias retirando-se 10 plantas aleatoriamente das parcelas. Em geral a helmintosporiose foi a doença predominante nas duas safras agrícolas e duas cultivares de aveia até o início do florescimento. A ferrugem da folha teve sua intensidade aumentada nos estádios subseqüentes. Na primeira parte deste trabalho procurou-se determinar as equações da função de dano pela análise de regressão entre intensidade de doença e rendimento de grãos para cada estádio de desenvolvimento das plantas. Foram obtidas equações significativas para as cultivares UPFA 20 e UPFA 22 nas duas safras agrícolas, onde por meio destas pode-se calcular o Limiar de Dano Econômico por estádio fenológico da cultura. Em sua segunda parte, os valores de incidência e severidade foliar foram utilizados para calcular à Área Abaixo da Curva de Progresso da Doença (AACPD), os quais foram correlacionados com o rendimento de grãos, massa de mil grãos e peso do hectolitro. Houve correlações negativas e significativas da AACPD com rendimento de grãos, massa de mil grãos e peso do hectolitro nas duas safras agrícolas. Destes concluiu-se que quanto maior a intensidade das doenças foliares maior são os valores da AACPD, resultando na diminuição dos valores das variáveis produtivas. De posse dos valores de rendimento de grãos, massa de mil grãos e peso do hectolitro a terceira parte deste trabalho teve como objetivo quantificar o percentual de dano, e controle destas duas doenças em função do número e dose de aplicação do fungicida. Os danos ao rendimento de grãos, massa de mil grãos e peso do hectolitro foram maiores na safra de 2007 para as duas cultivares. A percentagem de controle das doenças foliares foi maior nas duas cultivares na safra de 2007, atingindo com base na severidade foliar 86,74 % e 85,90 %, respectivamente para UPFA 20 e UPFA 22

A atividade florestal apresenta-se como um vetor de desenvolvimento social, ambiental e econômico no Brasil. Em 2004 as exportações ligadas ao setor renderam US$ 7 bilhões e contribuíram com US$ 5,5 bilhões em impostos. No mesmo ano, no Brasil, dos 6 milhões de hectares de reflorestamento comercial, mais de 50% dos hectares são ocupados por eucalipto. Esta cultura pode ser utilizada para diversas funções, desde à produção de papel e celulose, até a produção de carvão vegetal. Mas a produtividade desta cultura atualmente tem uma série de fatores limitantes. Destes fatores, um dos mais severos é uma doença denominada ferrugem, causada pelo fungo Puccinia psiddii Winter. Este patógeno entre tanto, não é conhecido nos centros de origem do gênero Eucalyptus, mas, utiliza como hospedeiros vários gêneros das Mirtáceas, infectando folhas, flores e frutos em desenvolvimento. O controle da doença é normalmente realizado mediante o uso de fungicidas. Porém, a utilização de plantas resistentes é o método mais aconselhável por diversos motivos, como o baixo custo, a praticidade e o menor impacto ambiental. Neste trabalho a metodologia do SAGE - Serial Analysis of Gene Expression foi utilizada, para a análise da expressão gênica uma vez que permite detectar e quantificar, de maneira global, a expressão de genes conhecidos e desconhecidos, envolvidos no processo de resistência à ferrugem. Neste trabalho analisou-se a expressão do conjunto de genes diferencialmente expressos e 200 genes sem diferenças no padrão de expressão, em Eucalyptus grandis infectado com Puccinia psidii. Utilizou-se para esta análise, indivíduos susceptíveis e resistentes à infecção por Puccinia psidii Winter. A população amostrada constituída por meios irmãos, apresentava segregação para o carácter de resistência à ferrugem. Os resultados produzidos permitiram identificar 421 genes com expressão diferencial (p ≤ 0,05) nos dois fenótipos. Vários destes genes estavam relacionados a diversos mecanismos de defesa da planta, tais como genes envolvidos na formação de barreiras físicas e na resposta hipersensível, resistência sistêmica adquirida, bem como genes relacionados à polarização celular e resposta ao estresse oxidativo. Os dados em conjunto, corroboram a idéia de que são vários os mecanismos que atuam simultaneamente produzindo o fenótipo resistente. Estes genes apresentam-se para serem utilizados futuramente como marcadores moleculares na seleção de indivíduos resistentes, em cruzamentos naturais ou dirigidos e como fonte de genes para experimentos de transformação em estudos mais profundos de fitopatogênese. / In Brazil the forest activities represent a vector for social, ambiental and economic development. In 2004 the exportations produced US$ 7 billions and contributed with US$ 5,5 billion in taxes. In the same year, in Brasil, of 6 million hectares of commercial reforestation, around 50% is occupied by eucalyptus. This crop can be used as the raw material for several industrial processes, from cellulose and paper production to vegetable charcoal production. However, eucalyptus productivity has several limiting factors. One of the most severe diseases is called rust, caused by the fungus Puccinia psiddii Winter. This pathogen is unknown in the Eucalyptus center of origin; however, it has several Myrtaceae genera as its host, infecting leaves, flowers and developing fruits. Rust management normally involves the use of fungicides, but the use of resistant plants is a much better alternative due the lower costs and minimal ambient impact. In the current study SAGE - Serial Analysis of Gene Expression was used for gene expression analysis because it is a quantitative genome-wide method and that obtains expression profiles from known and unknown genes involved in the rust resistant process. This thesis analyzed the expression profile of the differentially expressed genes and 200 genes without significant statistical differences in their expression patterns, in Eucalyptus grandis infected with Puccinia psidii. For this analysis we used susceptible and resistant individuals to Puccinia psidii Winter infection taken from a population half siblings, which showed segregation for fust resistance. The results indicated 421 genes with differential expression (p ≤ 0.05), 239 were preferentially expressed in the susceptible library and 232 in the resistant. Several of these genes were associated with plant defense mechanisms, such as genes involved in formation of physical barriers, hypersensitive response, systemic adquired resistance, genes related to cellular polarization and oxidative stress responses. All the data support the idea that not one but several mechanisms are acting at the same time producing the resistant phenotype. These genes are future candidates for molecular markers useful in the selection of resistant individuals in breeding programs and a source of genes for transformation experiments or as molecular tools to dissect the phytopathogenic process.

Made available in DSpace on 2014-06-11T19:22:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-06Bitstream added on 2014-06-13T20:48:38Z : No. of bitstreams: 1 lorenzetti_er_me_botfca.pdf: 1497737 bytes, checksum: 301fad7ec025809e7f69e3df89b5a8b9 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Cymbopogon citratus (DC.) Stapf é uma gramínea perene, de grande importância para a indústria farmacêutica e alimentícia, fornecedora de óleo essencial. Um problema limitante para a produção comercial é a ferrugem, causada pelo patógeno Puccinia nakanishikii Dietel. O trabalho objetivou estudar a interação patógeno-hospedeiro e availar princípios ativos naturais no controle da doença. Para os estudos anatômicos foram elaborados cortes, objetivando analisar as estruturas lesionadas e o desenvolvimento do patógeno. Foram avaliadas as trocas gasosas nas diferentes severidades da doença. Realizaram-se testes in vitro, com diferentes agentes de controle sobre a germinação de esporos do patógeno, sendo estes: óleos essenciais de eucalipto, palma-rosa, cravo-da-índia, menta, limão, citronela e mil-folhas; extrato pirolenhoso de eucalipto e mentol cristalizado. A partir destes testes foram escolhidos quatro agentes para os testes em campo, óleo de citronela e de eucalipto, extrato pirolenhoso e mentol. A área foi preparada a partir de mudas, sendo manejadas até os seis meses. Quando todas as plantas apresentavam sintomas, iniciaram-se os tratamentos com aplicações semanais. Foi avaliada ainda a doença após um corte. Os sintomas iniciais manifestam-se como manchas amareladas evoluindo para a formação de pústulas bronzeadas alongadas. Quanto à avaliação anatômica, após a infecção houve o desenvolvimento das estruturas fúngicas, prosseguindo com o rompimento da cutícula, possibilitando a observação das estruturas do patógeno de forma clara sobre as células da epiderme. Nas regiões lignificadas dos feixes vasculares não há desenvolvimento dessas estruturas. Com o aumento da severidade da doença observou-se a redução da assimilação de gás carbônico. A concentração interna de gás carbônico foi maior em severidades mais altas. Tal fato relaciona-se... / Cymbopogon citratus (DC) Stapf is a perennial grass, that has a large importance to the pharmaceutical and food industry, supplier of essential oil. One limiting problem to the commercial production is the rust caused by pathogen Puccinia nakanishikii Dietel. This work aimed to investigate the pathogen-host interactions and contribute to the researches with alternative methods of disease control. For anatomical studies were prepared anatomical sections, with the objective to analyze the structures injured and the development of the pathogen with different corants. On cultivated plants were evaluated gas exchange in different severity levels. In vitro tests were performed with different control agents, to the germination of pathogen spores, which are: essential oil of eucalyptus, palmarosa, clove, peppermint, lemon, citronella and yarrow; pyroligneous extract of eucalyptus and crystallized menthol. From these tests four products were chosen for the tests in a camp experiment, citronella oil, eucalyptus oil, pyroligneous extract and menthol. The area was prepared from seedlings, which were managed by six months age. When all plants had symptoms the treatments begin, with weekly applications. One avaliation happened after the cut of the lemongrass. The initial symptoms manifest as yellow spots progressing to formation of elongated pustules. These symptoms beginning with the development of fungal structures, after occurred the disruption of the cuticle, so the structures of the pathogen may be clearly observed on epidermis parenchyma cells of the leaf abaxial surface, however, in regions of vascular bundles, no development of such structures, these regions that have lignified structures. With the increase of the disease severity was a significant reduction in the assimilation of carbonic gas. The internal concentration of carbon dioxide was major... (Complete abstract click electronic access below)

Analyses of the large-scale population structure of pathogens enable the identification of migration patterns, diversity reservoirs or longevity of populations, the understanding of current evolutionary trajectories and the anticipation of future ones. A detailed analysis of populations in centre of diversity should enable to infer the adaptive capacity of the pathogen and identify potential sources for new invasions. Puccinia striiformis f.sp. tritici (PST) is the causal agent of wheat yellow/stripe rust, and despite a worldwide distribution, this fungus remains a model species for invasion studies, due to its long-distance migration capacity and recurrent local emergence of new strains. Little is known about the ancestral relationship of the worldwide PST population with unknown center of origin. We used multilocus microsatellite genotyping to infer the worldwide population structure of PST and the origin of new invasions, analysing a set of isolates representative of sampling performed over six continents. Bayesian and multivariate clustering methods partitioned the isolates into six distinct genetic groups, corresponding to distinct geographic areas. The assignment analysis confirmed the Middle East-Red Sea Area as the most likely source of newly spreading, high-temperature-adapted strains; Europe as the source of South American, North American and Australian populations; and Mediterranean-Central Asian populations as the origin of South African populations. The existence of strong population subdivision at worldwide level shows that major genetic groups are not markedly affected by recent dispersal events. However, the sources for recent invasions and the migration routes identified emphasize the importance of human activities on the recent long-distance spread of the disease. The analyses of linkage disequilibrium and genotypic diversity indicated a strong regional heterogeneity in levels of recombination, with clear signatures of recombination in the Himalayan (Nepal and Pakistan) and near-Himalayan (China) regions and a predominant clonal population structure in other regions. To explain the variability in diversity and recombination of worldwide PST populations, we assessed their sex ability in terms of telial production, the sex-specific structures that are obligatory for PST sexual cycle, in a set of 56 isolates representative of these worldwide geographical origins. We confirmed that the variability in genotypic diversity/ recombination was linked with the sex ability, pinpointing the Himalayan region as the possible center of origin of PST, from where it then spread worldwide. The reduced sex ability in clonal populations certainly reflects a loss of sexual function, associated to migration in areas where sexual alternate host is lacking, or not necessary for the completion of epidemic cycle. Approximate Bayesian computation analyses confirmed an out of Himalaya spread of PST, with Pakistan and China being the most ancestral population. A detailed analysis of Pakistani population at regional level revealed the existence of a strong population subdivision, a high genotypic diversity and the existence of recombination signature at each location reflecting the role of sexual recombination in the temporal maintenance at local level. A time spaced sampling of PST in the valley of Tianshui (China) inspired the development of a new estimator, allowing to quantify the relative contribution of sexual reproduction and effective population size on the basis of clonal resampling within and between years. A sexual reproduction rate of 74% (95% confidence interval [CI]: 38-95%) and effective population size of 1735 (95% CI: 675-2800) was quantified in Chinese PST population. The description of the origin and migration routes of PST populations worldwide and at its centre of diversity contributes to our understanding of PST evolutionary potential, and is helpful to build disease management strategies.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.

Thesis ( MScAgric) -- Stellenbosch University, 1997. / ENGLISH ABSTRACT: Stem rust is considered the most damaging of the wheat rusts causing yield losses of more than 50% in epidemic years. Similarly, Russian wheat aphids (RWA) can be regarded as one ofthe most devastating insect pests of wheat. Yield losses due to R W A primarily result from a reduction in plant resources (sucking plant sap). Secondary losses are incurred by viruses transmitted during feeding. Mapping disease and insect resistance genes that are effective against prevailing pathotypes and biotypes of South Africa will optimize their utilization in breeding programmes. The wheat line, 87M66-2-l, is homozygous for a single dominant stem rust resistance gene located on chromosome lD. This stem rust resistance gene has been derived from Triticum tauschii accession RL5289 and is here referred to as Srtau. The aim of this study was to determine the chromosome arm involved. Following the chromosome arm allocation of Srtau, its possible linkage with the genes Rg2, Lr 21 , Sr X and Sr 33 was studied. A telosomic analysis has shown that Srtau is located on chromosome arm 1 DS and is linked to the centromere with a recombination frequency of 21 ± 3 .40%. Glume blotch and a heavy mildew infection of segregating families planted in the field in 1996 made the linkage study between Lr 21 (leaf rust resistance) and Rg2 (glume colour) impossible. However, estimated linkages of 9 ± 1.9 map units between Sr33 (stem rust resistance) and Srtau, ± 6 map units between Sr X (stem rust resistance) and Sr 3 3 and ± 1 0 map units between Sr X and Srtau suggested that SrX, Sr33 and Srtau are closely linked on I DS. Taking existing map data into consideration, it seems that the most likely order of the genes is: centromere - Srtau - Sr 3 3 - Sr X. A single dominant R W A resistance gene, Dn5, was identified in the T aestivum accession 'SA 463' and is located on chromosome 7D. The aim ofthis study was to determine the chromosome arm involved. The possible linkage of Dn5 with the endopeptidase locus, Ep-D1 b. and chlorina mutant gene, cn-D1, was then studied. Endopeptidase zymograms of 'SA 463' revealed two unknown polymorphisms. F 2 monosomic analyses involving the chromosomes 7 A, 7B and 7D were performed in an attempt to identify the loci associated with these polymorphisms. Dn5 was mapped on chromosome arm 7DL. A recombination frequency of60 ± 4.53% between Dn5 and the centromere suggested the absence of linkage. Linkage between Ep-Dl and cn-Dl could not be calculated as a result of similar isoelectric points of the 7DL encoded endopeptidases of the parental material studied. Recombination frequencies of32 ± 4.97% between Dn5 and EpDl and 37 ± 6.30% between Dn5 and cn-Dl were, however, encountered. The two novel endopeptidase alleles encountered in 'SA 463' were designated as Ep-Dle and Ep-Ald. A RWA resistance gene was transferred from the rye accession ' Turkey 77' to wheat and in the process the RWA resistant wheat lines 91M37-7 and 91M37-51 were derived. No rye chromatin could be detected in these plants following C-banding. The aim of this study was to determine (i) on which chromosome the gene(s) is located, and (ii) whether the resistance can be the result of a small intercalary translocation of rye chromatin. A monosomic analysis of the RWA resistance gene in 91M37-51 has shown that a single dominant resistance gene occurs on chromosome 7D. The use of rye-specific dispersed probes did not reveal any polymorphisms between the negative controls and RW A resistant lines 91M3 7- 7 and 91M37-51 which would suggest that it is unlikely that the resistance was derived from rye. / AFRIKAANSE OPSOMMING: Stamroes word as die mees vemietigende graanroessiekte beskou en het in epidemiese jare oesverliese van meer as 50% tot gevolg. Russiese koringluise is eweneens een van die emstigste insekplae van koring. Russiese koringluise veroorsaak oesverliese deurdat dit plantsap uitsuig en die plant van voedingstowwe beroof. Dit tree egter ook as 'n virusvektor op en kan so indirekte oesverliese veroorsaak. Kartering van siekte- en insekweerstandsgene wat effektief is teen die Suid-Afrikaanse patotipes en biotipes, sal hulle gebruik in teelprogramme optimiseer. Die koringlyn, 87M66-2-l , is homosigoties vir 'n dominante stamroes-weerstandsgeen wat op chromosoom ID voorkom. Hierdie weerstandsgeen is uit die Triticum tauschii aanwins, RL5289, afkomstig en word hiema verwys as Srtau. Daar is gepoog om te bepaal op watter chromosoomarm Srtau voorkom, waama sy koppeling met betrekking tot die gene Rg2, Lr21 , SrX en Sr33 bepaal is. 'n Telosoomanalise het getoon dat Srtau op chromosoom-arm 1 DS voorkom en gekoppel is aan die sentromeer met 'n rekombinasie-frekwensie van 21 ± 3.40%. Segregerende populasies wat in 1996 in die land geplant is, is hewig deur aarvlek en poeieragtige meeldou besmet en dit het die moontlike bepaling van koppeling tussen Lr21 (blaarroesweerstand) en Rg2 (aarkaffie kleur) belemmer. Koppelingsafstande van 9 ± 1. 9 kaart-eenhede tussen Sr 33 (stamroesweerstand) en Srt au, ± 6 kaart -eenhede tussen Sr X ( stamroesweerstand) en Sr 3 3 en ± 1 0 kaart -eenhede tussen SrX en Srtau is geraam en toon dat SrX, Sr33 en Srtau nou gekoppel is. Die waarskynlikste volgorde van die gene op lDS is: sentromeer- Srtau- Sr33- SrX. 'n Enkele dominante Russiese koringluis-weerstandsgeen, Dn5, is in dieT aestivum aanwins 'SA 463 ' ge"identifiseer en kom op chromosoom 7D voor. Die studie het ten doel gehad om te bepaal op watter chromosoom-arm Dn5 voorkom, asook wat die koppeling van Dn5 met die endopeptidase lokus, Ep-Dl, en die chlorina mutante geen, cn-Dl , is. Endopeptidase simograrnme van 'SA 463' het twee onbekende polimorfismes getoon. Die gene wat kodeer vir hierdie twee polimorfismes is met behulp van F2 monosoom-analises wat die chromosome 7 A, 7B en 7D betrek, gei:dentifiseer. Dn5 is op chromosoom 7DL gekarteer. 'n Rekombinasie-frekwensie van 60 ± 4.53% is gevind vir die sentromeer en Dn5 en dui op die afwesigheid van koppeling. Koppeling tussen Ep-Dl en cn-Dl kon nie bepaal word nie omdat die endopeptidase bande geproduseer deur die ouerlike materiaal wat in die studie gebruik is, nie met sekerheid in die nageslag onderskei kon word nie. Rekombinasie-frekwensies van 32 ± 4.97% tussen Dn5 en Ep-Dl en 37 ± 6.30% tussen Dn5 en cn-Dl is egter bereken. Dit word voorgestel dat daar na die twee onbekende endopeptidase-allele wat in 'SA 463 ' voorkom, verwys word as Ep-Dle en Ep-Ald. 'n Russiese koringluis-weerstandsgeen is uit die rog-aanwins, 'Turkey 77', oorgedra na koring en in die proses is die Russies koringluis weerstandbiedende lyne, 91M37-7 en 91M37-51 , geproduseer. Geen rog-chromatien kon egter met behulp van C-bande in hierdie lyne waargeneem word nie. Die doel van die studie was om te bepaal (i) op watter chromosoom die geen(e) voorkom, en (ii), of die Russiese koringluis weerstandsgeen die gevolg kan wees van 'n klein interkalere translokasie van rog- chromatien. 'n Monosoom-analise van die Russiese koringluis-weerstandsgeen in 91M37-51 het getoon dat 'n enkele dominante weerstandsgeen op chromosoom 7D voorkom. Rog-spesifieke herhalende peilers het geen polimorfismes tussen negatiewe kontroles en die Russiese koringluis weerstandbiedende lyne 91M37-7 en 91M37-51 getoon nie. Dit is dus onwaarskynlik dat die weerstand in die lyne uit rog verhaal is.