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Sintomas típicos de infecção por fitoplasmas foram encontrados em plantas de gergelim cultivadas comercialmente. Estes sintomas se caracterizavam pela intensa proliferação de ramos, presença abundante de folhas levemente cloróticas e de tamanho menor que as normais, além de pétalas de coloração verde. A partir de plantas afetadas foi extraído o DNA total, o qual foi usado em reações de duplo PCR, visando detectar fitoplasmas nos tecidos vegetais. Fragmentos genômicos de 1,2 Kb da região do 16S rDNA foram amplificados demonstrando a constante associação entre fitoplasmas e plantas doentes. Através de duplo PCR usando primers específicos, foi identificado um fitoplasma pertencente ao grupo 16SrI em todas as amostras sintomáticas analisadas. Com base no sequenciamento desta região genômica e na digestão in sílico, as análises virtuais de RFLP revelaram que um dos fitoplasmas presentes nas amostras de gergelim era afiliado ao subgrupo 16SrI-B. No entanto, os padrões de restrição apresentados pelo outro fitoplasma mostraram que o mesmo era distinto dos demais representantes dos subgrupos que constituem o grupo 16SrI. Os valores calculados de coeficientes de similaridade e os mapas putativos de restrição confirmaram os resultados da análise de RFLP, indicando que este fitoplasma era representante de um novo subgrupo. A árvore filogenética, construída a partir das sequências nucleotídicas do 16S rDNA de diversos fitoplasmas evidenciou que este novo fitoplasma emergia de um ramo distinto, considerando as ramificações dentro do grupo 16SrI. A filodia do gergelim foi anteriormente relatada em vários países, sendo associada com fitoplasmas dos grupos 16SrI, 16SrII e 16SrVI. O presente trabalho revelou a ocorrência de dois fitoplasmas associados à filodia, sendo um deles pertencente ao subgrupo 16SrI-B e outro caracterizado como representante de um novo subgrupo, aqui denominado 16SrI-X. / Typical symptoms commonly induced by phytoplasmas were found in sesame plants grown in commercial fields. These symptoms were characterized by shoot proliferation, leaves of reduced size exhibiting light chlorosis, and green petals. Total DNA extracts were obtained from diseased plants and used as template in nested PCR, in order to detect phytoplasmas in the tissues of the hosts. Genomic fragments of 1.2 kb corresponding to the 16S rDNA region were amplified demonstrating the association of phytoplasmas and diseased plants. Using nested PCR with specific primers, a phytoplasma belonging to group 16SrI was identified in all symptomatic samples. Based on the sequencing of 16S rDNA and in silico digestion, the virtual RFLP analysis allowed identify the presence of a phytoplasma affiliated with the subgroup 16SrI-B. This analysis also revealed a second phytoplasma distinct of all representatives of the subgroups within the group 16SrI. Similarity coefficients values and analysis of putative restriction sites confirmed the results obtained from virtual RFLP analysis indicating that this phytoplasma was representative of a new subgroup. A phylogenetic tree generated by the 16S rDNA sequences belonging to diverse phytoplasmas evidenced that this new phytoplasma emerged from a distinct branch, within of the 16SrI group. The sesame phyllody was previously reported in various countries in association with phytoplasmas belonging to 16SrI, 16SrII, and 16SrVI groups. The present study revealed the association of the phyllody with a phytoplasma affiliated with 16SrI-B and a phytoplasma representative of a new subgroup here named 16SrI-X.

Fitoplasmas são procariotos sem parede celular, pertencentes à classe dos Mollicutes, que habitam os vasos de floema e causam doenças de relevância econômica em uma ampla gama de espécies vegetais. A videira (Vitis sp) é a terceira fruteira mais cultivada no mundo e apresenta elevada importância econômica no Brasil. Aspectos fitossanitários se constituem em fatores limitantes da produção, com destaque para as doenças causadas por fitoplasmas, denominadas de amarelos. Essas doenças estão amplamente disseminadas nos continentes europeu e americano, ocorrendo em tradicionais países produtores. Plantas exibindo sintomas característicos da doença têm sido também observadas em cultivos comerciais localizados em algumas áreas do território brasileiro. Visando investigar este tipo de doença, plantas sintomáticas foram amostradas em parreirais comerciais dos Estados de São Paulo e Paraná e mantidas em casa de vegetação. O presente estudo visou demonstrar a associação entre fitoplasmas e os amarelos, identificar e analisar filogeneticamente os fitoplasmas detectados, demonstrar sua transmissão para plantas sadias e determinar o melhor estádio fenológico da planta para amostragem de tecidos, para confirmação da diagnose. Para isto, durante 45 meses, amostras foram coletadas de plantas doentes envasadas sendo usado o método de PCR, análise de RFLP, sequenciamento das bases nucleotídicas e enxertia de tecidos entre plantas de videira. Os produtos amplificados em PCR evidenciaram a presença de fitoplasmas em todas as plantas portadoras de amarelos. Estes fitoplasmas foram identificados como representantes dos grupos 16SrI-B e 16SrIII, os quais ocorreram em infecções simples ou mistas. Os fitoplasmas apareceram em todas as fases de desenvolvimento da planta, porém com maior freqüência nas amostras coletadas no estádio fenológico correspondente à brotação de ramos e aparecimento de folhas novas. Esta fase se mostrou a mais indicada para as amostragens, visando à detecção de fitoplasmas para fins de diagnose. A transmissão dos fitoplasmas por enxertia foi alta, demonstrando que estes são os agentes causais da doença e que inspeções devem ser adotadas como medida de controle para evitar sua disseminação via material de propagação vegetativa. / Phytoplasmas are wall-less prokaryotes, phloem-limited plant pathogens, belonging to Mollicute class. They are agents of diseases that cause serious damage to a diversity of cultivated especies. Grapevine (Vitis sp) is the third most cultivated fruit crop in the world and it has high economical impact in Brazil. Phytossanitary aspects are important production constraint factors, especially regarding diseases caused by phytoplasmas, which are generally known as grapevine yellows. These diseases are widely spread throughout main producer countries, located in Europe and North America. Plants exhibiting typical symptoms of the disease have also been observed in crops located in some areas of Brazilian territory. In order to investigate this kind of malady, symptomatic plants were sampled from commercial vineyards located in the States of São Paulo and Paraná, Brazil and kept in greenhouse conditions. The present study aimed to: demonstrate the association between phytoplasmas and yellows; identify and analyse phylogenetically the detected phytoplasmas; demonstrate their transmission to healthy plants and determinate optimal phenologycal stage for phytoplasma detection to diagnosis confirmation. Samples were collected from diseased plotted plants grown during 45 months. PCR method, RFLP analyses, sequencing of nucleotide bases from 16S rRNA, and grafting technique were used in this study. Amplified genomic fragments revealed the presence of phytoplasmas in all plants with symptoms of yellows. Those phytoplasmas were identified as representatives of the groups 16SrI-B and 16SrIII, occurring in simple and mixed infections. Phytoplasmas were detected in all phenological stages evaluated, but they occurred with high frequences in material collected during budburst. These stage may be considered as the most indicated for sampling to confirm diagnosis based on symptomatology. Phytoplasmas transmission by grafting of healthy scion grafts onto infected rootstocks was high, demonstrating that they are the disease agents and inspection is a control practice that must be adopted to prevent their dissemination through propagative material.

O melão-de-São-Caetano (Momordica charantia L) é uma cucurbitácea que ocorre em todas as regiões geográficas brasileiras. A espécie apresenta duas \"variedades\" distintas, comumente conhecidas por \"variedade silvestre\" e \"variedade cultivada\", esta última caracterizada por plantas de maior tamanho. Plantas da \"variedade selvagem\" são hospedeiras de um fitoplasma do grupo 16SrIII-J, que causa superbrotamento de ramos, nanismo generalizado, clorose, redução no tamanho de folhas e frutos. No entanto, não há informação da \"variedade cultivada\" ser hospedeira de fitoplasmas. Assim, no presente estudo, plantas sintomáticas desta \"variedade\" foram analisadas quanto à presença de fitoplasmas em seus tecidos, visando associar este tipo de patógeno à doença. Neste mesmo trabalho, os isolados do fitoplasma encontrados nas plantas sintomáticas da \"variedade cultivada\" foram molecularmente analisados em relação ao gene secY, atualmente usado como um marcador que permite identificar variações genéticas sutis. Buscou-se, com isto, identificar possíveis variantes entre os isolados. Amplificações de fragmentos de DNA a partir dos genes 16S rRNA (1,2Kb) e secY (1,6Kb) demonstraram a associação de fitoplasma do grupo 16SrIII com as plantas sintomáticas de melão-de-São-Caetano da \"variedade cultivada\". Nestas plantas, corpúsculos pleomórficos, típicos de fitoplasmas, foram visualizados no floema dos tecidos doentes, confirmando os resultados dos testes moleculares. Análises de RFLP virtual, conduzidas com o fragmento genômico correspondente ao gene secY e diversas enzimas de restrição, permitiram identificar o referido fitoplasma como pertencente ao subgrupo 16SrIIIJ. A análise filogenética evidenciou que o fitoplasma padrão do subgrupo 16SrIII-J emergiu do mesmo ramo que o fitoplasma identificado no melão-de-São-Caetano, confirmando que ambos estão estritamente relacionados. O emprego do gene secY como marcador para diferenciação fina entre fitoplasmas não apontou variabilidade genética entre os isolados do fitoplasma detectado tanto nas plantas da \"variedade cultivada\" como naquelas pertencentes à \"variedade selvagem\". Como conclusão, a \"variedade cultivada\" de M. charantia é hospedeira do mesmo fitoplasma encontrado na \"variedade selvagem\", o qual é afiliado ao subgrupo 16SrIII-J; por sua vez, o gene seY não distinguiu geneticamente os isolados do fitoplasma pertencente ao subgrupo 16SrIII-J, presentes nas plantas de melão-de-São- Caetano. / Momordica charantia is a species of the family Cucurbitaceae that occurs in all Brazilian geographic regions. This species presents two distinct \"varieties\", commonly called \"wild variety\" and \"cultivated variety\", whose plants are bigger than those belonging to the \"wild variety\". Plants of the \"wild variety\" are hosts of a phytoplasma of the group 16SrIII-J, which is associated with shoot proliferation, stunting, chlorosis, and small leaves and fruits. However, there is no information about the occurrence of phytoplasmas in plants of the \"cultivated variety\". Thus, in the present study, symptomatic plants belonging to this \"variety\" were analysed in order to associate phytoplasmas with the disease. In addition, strains of the phytoplasma found in symptomatic plants of the \"cultivated variety\" were molecularly analyzed in relation to the gene secY, which is currently used as a marker for identification fine of genetic diversity, aiming provide elements for construction of new schemes for classification of phytoplasmas. The objective was to identify distinct strains among the strains present in plants of the wild and cultivated varieties. Amplifications of DNA fragments from the genes 16Sr rRNA (1.2Kb) and secY (1.6Kb) demonstrated the association of a phytoplasma of group 16SrIII with the symptomatic plants belonging to \"cultivated variety\". These plants revealed the presence of pleomorphic bodies, typical of phytoplasmas, which was visualized in the phloem vessel from diseased tissues, confirming the results obtained by molecular assays. Virtual RFLP analysis, performed with the genomic fragment corresponding to the gene secY and various restriction enzymes, allowed to identify this phytoplasma as a member of the subgroup 16SrIII-J. Phylogenetic analysis revealed that the phytoplasma used as reference for 16SrIII-J subgroup and the phytoplasma identified in plants of M. charantia emerged from the same branch, confirming that both phytoplasmas are closely related. The gene secY, used as marker for fine differentiation of phythoplasmas, did not show genetic variability among the strains of the phytoplasma detected both plants belonging to \"cultivated variety\" and \"wild variety\". In conclusion, plants of the \"cultivated variety\" are hosts of the same phytoplasma found in the \"wild variety, which is affiliated with the 16SrIII-J subgroup; in addition, the gene secY did not distinguish isolates of the phytoplasma belonging to 16SrIII-J subgroup, present in plants of M. charantia.

Plantas apresentando folhas com deformações do tipo bolhas, menor quantidade de vagens de tamanho reduzido e contendo menor número de sementes, vagens que não completaram a maturação e coloração verde da parte aérea no final do ciclo foram observadas em campos de produção. As plantas foram analisadas visando à detecção de fitoplasmas e a sua identificação molecular. Para isto, o DNA total das plantas amostradas foi submetido ao teste de duplo PCR conduzido com primers específicos para a região do 16S rDNA de fitoplasmas. As amplificações evidenciaram que fitoplasmas estavam presentes em tecidos de plantas sintomáticas. O duplo PCR realizado com primers grupo-específicos revelou a ocorrência de fitoplasmas afiliados aos grupos 16SrI e 16SrIII. As análises virtuais de RFLP, baseadas no sequenciamento da referida região genômica, permitiram identificar um dos fitoplasmas como pertencente ao subgrupo 16SrI-B. Os valores de coeficientes de similaridade, calculados com base nos padrões de restrição gerados in silico por 17 enzimas, confirmaram a identidade deste fitoplasma. Ainda, mapas de restrição mostraram que o fitoplasma encontrado em plantas de soja apresentava sítios putativos de restrição idênticos a um fitoplasma típico do grupo 16SrI-B. A análise filogenética, envolvendo o fitoplasma alvo deste estudo e fitoplasmas representantes de alguns grupos e subgrupos relatados no Brasil, mostrou que o fitoplasma da soja estava estritamente relacionado com aqueles componentes do grupo 16SrI. O fitoplasma em estudo emergiu do mesmo ramo da árvore filogenética também compartilhado por fitoplasmas do grupo 16SrI, confirmando os resultados dos demais testes moleculares. Os resultados gerados neste trabalho evidenciaram que a soja pode ser considerada como mais um hospedeiro de fitoplasmas pertencentes aos grupos 16SrI e 16SrIII, os quais tem sido relatados em associação com diversas doenças de plantas que ocorrem no Brasil. Este estudo também gera informações que podem contribuir para aumentar os conhecimentos sobre este emergente grupo de agentes causais de doença. / Plants exhibiting leaf deformation type bubbles, low quantities of pods of reduced size containing few seeds, pods not mature, and green color of stem and leaves in the end of crop growth were observed in commercial fields. The plants were tested for the detection of phytoplasmas and their molecular identification. For this, the total DNA of plants sampled was submitted to nested PCR assays conducted with universal primers for amplification of a fragment corresponding to the 16S rDNA of phytoplasmas. The amplifications revealed the presence of phytoplasmas in tissues of symptomatic plants. For identification, nested PCR performed with group-specific primers demonstrated the occurrence of phytoplasmas affiliated to the groups 16SrI and 16SrIII. The virtual RFLP analysis, based on the sequencing of DNA fragments generated from nested PCR with universal primers, allowed the identification of a phytoplasma belonging to the subgroup 16SrI-B. The values of similarity coefficients, calculated on the basis of restriction patterns generated in silico for 17 enzymes, confirmed the identity of this phytoplasma. Furthermore, restriction maps showed that the phytoplasma found in soybean plants had putative restriction sites identical to those phytoplasma of the group 16SI-B. Phylogenetic analysis, involving the phytoplasma identified in the present study and representatives of some groups and subgroups previously reported in Brazil, showed that the soybean phytoplasma was closely related to phytoplasmas belonging to group 16SrI. The studied phytoplasma and phytoplasmas belonging to group 16SrI emerged from the same branch, confirming the results obtained by PCR and RFLP analysis. Also, based on the results, soybean could be considered as a host for phytoplasmas belonging to the group 16SrI and 16SrIII, which has been reported in association with various diseases that occur in Brazil. The present study may contribute to improve the knowledge about this emerging group of causal agents of disease.

Sintomas típicos de infecção por fitoplasmas foram encontrados em plantas de gergelim cultivadas comercialmente. Estes sintomas se caracterizavam pela intensa proliferação de ramos, presença abundante de folhas levemente cloróticas e de tamanho menor que as normais, além de pétalas de coloração verde. A partir de plantas afetadas foi extraído o DNA total, o qual foi usado em reações de duplo PCR, visando detectar fitoplasmas nos tecidos vegetais. Fragmentos genômicos de 1,2 Kb da região do 16S rDNA foram amplificados demonstrando a constante associação entre fitoplasmas e plantas doentes. Através de duplo PCR usando primers específicos, foi identificado um fitoplasma pertencente ao grupo 16SrI em todas as amostras sintomáticas analisadas. Com base no sequenciamento desta região genômica e na digestão in sílico, as análises virtuais de RFLP revelaram que um dos fitoplasmas presentes nas amostras de gergelim era afiliado ao subgrupo 16SrI-B. No entanto, os padrões de restrição apresentados pelo outro fitoplasma mostraram que o mesmo era distinto dos demais representantes dos subgrupos que constituem o grupo 16SrI. Os valores calculados de coeficientes de similaridade e os mapas putativos de restrição confirmaram os resultados da análise de RFLP, indicando que este fitoplasma era representante de um novo subgrupo. A árvore filogenética, construída a partir das sequências nucleotídicas do 16S rDNA de diversos fitoplasmas evidenciou que este novo fitoplasma emergia de um ramo distinto, considerando as ramificações dentro do grupo 16SrI. A filodia do gergelim foi anteriormente relatada em vários países, sendo associada com fitoplasmas dos grupos 16SrI, 16SrII e 16SrVI. O presente trabalho revelou a ocorrência de dois fitoplasmas associados à filodia, sendo um deles pertencente ao subgrupo 16SrI-B e outro caracterizado como representante de um novo subgrupo, aqui denominado 16SrI-X. / Typical symptoms commonly induced by phytoplasmas were found in sesame plants grown in commercial fields. These symptoms were characterized by shoot proliferation, leaves of reduced size exhibiting light chlorosis, and green petals. Total DNA extracts were obtained from diseased plants and used as template in nested PCR, in order to detect phytoplasmas in the tissues of the hosts. Genomic fragments of 1.2 kb corresponding to the 16S rDNA region were amplified demonstrating the association of phytoplasmas and diseased plants. Using nested PCR with specific primers, a phytoplasma belonging to group 16SrI was identified in all symptomatic samples. Based on the sequencing of 16S rDNA and in silico digestion, the virtual RFLP analysis allowed identify the presence of a phytoplasma affiliated with the subgroup 16SrI-B. This analysis also revealed a second phytoplasma distinct of all representatives of the subgroups within the group 16SrI. Similarity coefficients values and analysis of putative restriction sites confirmed the results obtained from virtual RFLP analysis indicating that this phytoplasma was representative of a new subgroup. A phylogenetic tree generated by the 16S rDNA sequences belonging to diverse phytoplasmas evidenced that this new phytoplasma emerged from a distinct branch, within of the 16SrI group. The sesame phyllody was previously reported in various countries in association with phytoplasmas belonging to 16SrI, 16SrII, and 16SrVI groups. The present study revealed the association of the phyllody with a phytoplasma affiliated with 16SrI-B and a phytoplasma representative of a new subgroup here named 16SrI-X.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1961. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 84-87).

Thesis (Ph. D.)--University of Wisconsin, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: South Africa is ranked eighth in the world as far as international wine production is concerned and in terms of area under bearing vines South Africa is ranked 12th. In 2011 the wine industry contributed R4 204.4 million to the South African economy in state revenue from wine products. The importance of viticulture to the economy of South Africa forces the industry to limit the effect of all disease causing pathogens in order to keep their competitive edge. Aster yellows (AY) phytoplasma 16SrI-B subgroup was reported for the first time in grapevine (Vitis vinifera L. (Vitaceae)) in South Africa in 2006. Worldwide phytoplasma diseases of grapevine cause serious damage ranging from lower yields to the death of vines. The lack of knowledge about the epidemiology of AY disease makes it difficult to determine the impact of the disease on the South African wine industry. The aim of this study was to conduct surveys in disease-affected vineyards in the Vredendal region to determine the incidence and spatial distribution of the disease in a variety of cultivars. The field surveys based on visual symptoms of AY disease were confirmed by polymerase chain reaction (PCR). A survey was also conducted in and around AY-infected vineyards in search of possible alternative host plants of the phytoplasma. Spatial distribution of AY-affected vines were analysed using the PATCHY spatial analysis package. A rapid decline of AY-affected Chardonnay eventually leading to the death of vines was observed, confirming the sensitivity of Chardonnay towards grapevine yellows infections. Symptomless AY infections occurred and AY could not be detected in all symptomatic vines, which indicate uneven distribution of AY in individual vines. Molecular analyses using PCR-RFLP showed that all vines sampled in the Vredendal vicinity contained AY phytoplasma only. No phytoplasmas were present in any weeds or other possible host plants tested. Although the mean yearly disease incidences of Chardonnay (29.95%) and Chenin blanc (16.64%) were higher than Pinotage (5.80%) over the four-year survey period, there was no statistically significant difference between the disease incidences of these three cultivars. The mean yearly disease incidence showed a trend over time and the disease incidence of the first year was significantly lower than that of the other years. Chardonnay showed a cumulative disease incidence of 37.77% at the end of the 4-year study which means that Chardonnay vineyards can be 100% AY infected in ten years’ time. Spatial distribution patterns of AY-infected vines were mostly non-random with clustering of disease affected vines along and across vine rows. With the exception of one vineyard, aggregation of AY-affected vines mostly occurred on the edge of vineyards adjacent to infected vineyards. This epidemiological study gives an indication of the sensitivity of the different cultivars towards AY, the tempo of spreading and the future impact of the disease on the South African wine industry. It also contributes valuable information towards the development of a management strategy for grapevine yellows disease in South African vineyards. / AFRIKAANSE OPSOMMING: Suid- Afrika is op agtste op die wêreld ranglys wat internasionale produksie van wyn aan betref, en in terme van oppervlakte onder wingerd, is Suid-Afrika 12de. In 2011 het die wynbedryf R4 204.4 miljoen tot die Suid-Afrikaanse ekonomie bygedra in staats inkomste uit wyn produkte. Die belangrikheid van wingerd tot die ekonomie van Suid-Afrika dwing die bedryf om die effek van alle siekteveroorsakende patogene te beperk, om sodoende hul kompeterende voordeel te behou. Aster vergeling (AY) fitoplasma 16SrI-B subgroep is vir die eerste keer in 2006 in wingerd (Vitis vinifera L. (Vitaceae)) in Suid-Afrika waargeneem. Fitoplasma siektes van wingerd veroorsaak wêreldwyd ernstige skade wat wissel van laer opbrengste tot die afsterf van wingerdstokke. Die gebrek aan kennis oor die epidemiologie van astervergeling siekte maak dit moeilik om die impak van die siekte op die Suid-Afrikaanse wynbedryf te bepaal. Die doel van hierdie studie was om ‘n opname te maak in siekte geaffekteerde wingerde in die Vredendal omgewing om sodoende siekte voorkoms en verspreidingspatrone van die siekte in 'n verskeidenheid van kultivars te bepaal. Die veld opnames, gebaseer op visuele simptome van aster vergeling siekte, was bevestig deur polimerase kettingreaksie (PKR). ‘n Opname is ook in en om aster vergeling geaffekteerde wingerde uitgevoer, op soek na moontlike alternatiewe gasheer plante van die fitoplasma. Verspreidingspatrone van astervergeling geaffekteerde wingerde is ontleed met behulp van die PATCHY ruimtelike analise pakket. 'n Vinnige agteruitgang van AY geaffekteerde Chardonnay, wat uiteindelik gelei het tot die afsterf van wingerde, is waargeneem, wat die sensitiwiteit van Chardonnay teenoor wingerdvergeling infeksie bevestig. Simptoomlose astervergeling fitoplasma infeksies kom voor en astervergeling fitoplasma kon nie opgespoor word in alle simptomatiese wingerdstokke nie, wat op oneweredige verspreiding van AY fitoplasma in individuele wingerdstokke dui. Molekulêre ontledings met behulp van PKR-RFLP het getoon dat alle wingerdstokke, wat in die Vredendal omgewing getoets is, slegs astervergeling fitoplasma bevat. Geen fitoplasmas was teenwoordig in enige onkruide of ander moontlike gasheer plante. Hoewel die gemiddelde jaarlikse siekte voorkoms van Chardonnay (29,95%) en Chenin Blanc (16,64%) oor die vier-jaar opname periode hoër was as dié van Pinotage (5,80%), was daar geen statisties beduidende verskil tussen die siekte voorkoms van hierdie drie kultivars nie. Die gemiddelde jaarlikse siekte voorkoms het 'n tendens oor tyd getoon, en die siekte voorkoms van die eerste jaar was betekenisvol laer as dié van die ander jare. Chardonnay het ‘n kumulatiewe siekte voorkoms van 37.77% aan die einde van die 4-jaar studie getoon, wat beteken dat Chardonnay wingerde binne 10 jaar 100% besmet kan wees met AY. Verspreidingspatrone van AY geaffekteerde wingerdstokke was meestal nie-ewekansig met bondeling van geaffekteerde wingerdstokke in en oor wingerd rye. Bondeling van AY geaffekteerde wingerdstokke het, met die uitsondering van een wingerd, meestal op die kant van wingerde aanliggend aan besmette wingerde, voorgekom. Die epidemiologiese studie gee 'n aanduiding van die sensitiwiteit van die verskillende kultivars ten opsigte van AY, die tempo van die verspreiding en die toekomstige impak van die siekte op die Suid-Afrikaanse wynbedryf. Dit dra ook waardevolle inligting by tot die ontwikkeling van 'n strategie vir die bestuur van wingerdvergeling siekte in Suid-Afrikaanse wingerde.

Plantas apresentando folhas com deformações do tipo bolhas, menor quantidade de vagens de tamanho reduzido e contendo menor número de sementes, vagens que não completaram a maturação e coloração verde da parte aérea no final do ciclo foram observadas em campos de produção. As plantas foram analisadas visando à detecção de fitoplasmas e a sua identificação molecular. Para isto, o DNA total das plantas amostradas foi submetido ao teste de duplo PCR conduzido com primers específicos para a região do 16S rDNA de fitoplasmas. As amplificações evidenciaram que fitoplasmas estavam presentes em tecidos de plantas sintomáticas. O duplo PCR realizado com primers grupo-específicos revelou a ocorrência de fitoplasmas afiliados aos grupos 16SrI e 16SrIII. As análises virtuais de RFLP, baseadas no sequenciamento da referida região genômica, permitiram identificar um dos fitoplasmas como pertencente ao subgrupo 16SrI-B. Os valores de coeficientes de similaridade, calculados com base nos padrões de restrição gerados in silico por 17 enzimas, confirmaram a identidade deste fitoplasma. Ainda, mapas de restrição mostraram que o fitoplasma encontrado em plantas de soja apresentava sítios putativos de restrição idênticos a um fitoplasma típico do grupo 16SrI-B. A análise filogenética, envolvendo o fitoplasma alvo deste estudo e fitoplasmas representantes de alguns grupos e subgrupos relatados no Brasil, mostrou que o fitoplasma da soja estava estritamente relacionado com aqueles componentes do grupo 16SrI. O fitoplasma em estudo emergiu do mesmo ramo da árvore filogenética também compartilhado por fitoplasmas do grupo 16SrI, confirmando os resultados dos demais testes moleculares. Os resultados gerados neste trabalho evidenciaram que a soja pode ser considerada como mais um hospedeiro de fitoplasmas pertencentes aos grupos 16SrI e 16SrIII, os quais tem sido relatados em associação com diversas doenças de plantas que ocorrem no Brasil. Este estudo também gera informações que podem contribuir para aumentar os conhecimentos sobre este emergente grupo de agentes causais de doença. / Plants exhibiting leaf deformation type bubbles, low quantities of pods of reduced size containing few seeds, pods not mature, and green color of stem and leaves in the end of crop growth were observed in commercial fields. The plants were tested for the detection of phytoplasmas and their molecular identification. For this, the total DNA of plants sampled was submitted to nested PCR assays conducted with universal primers for amplification of a fragment corresponding to the 16S rDNA of phytoplasmas. The amplifications revealed the presence of phytoplasmas in tissues of symptomatic plants. For identification, nested PCR performed with group-specific primers demonstrated the occurrence of phytoplasmas affiliated to the groups 16SrI and 16SrIII. The virtual RFLP analysis, based on the sequencing of DNA fragments generated from nested PCR with universal primers, allowed the identification of a phytoplasma belonging to the subgroup 16SrI-B. The values of similarity coefficients, calculated on the basis of restriction patterns generated in silico for 17 enzymes, confirmed the identity of this phytoplasma. Furthermore, restriction maps showed that the phytoplasma found in soybean plants had putative restriction sites identical to those phytoplasma of the group 16SI-B. Phylogenetic analysis, involving the phytoplasma identified in the present study and representatives of some groups and subgroups previously reported in Brazil, showed that the soybean phytoplasma was closely related to phytoplasmas belonging to group 16SrI. The studied phytoplasma and phytoplasmas belonging to group 16SrI emerged from the same branch, confirming the results obtained by PCR and RFLP analysis. Also, based on the results, soybean could be considered as a host for phytoplasmas belonging to the group 16SrI and 16SrIII, which has been reported in association with various diseases that occur in Brazil. The present study may contribute to improve the knowledge about this emerging group of causal agents of disease.