No description available.

Downy mildew, caused by the biotrophic Oomycete Plasmopara viticola, is one of the most important diseases of grapevines world wide. It is particularly destructive in temperate viticultural regions that experience warm wet conditions during the vegetative growth of the vine (Wong et al., 2001). The disease is not normally a problem in mediterranean climates where the growing season tends to be hot and dry (Mullins et al., 1992; Sivasithamparam, 1993). Grape downy mildew is however a major disease in Australian viticulture (McLean et al., 1984; Magarey et al., 1991). Grape downy mildew was first reported in Europe in 1878 (Viennot-Bourgin, 1981). In Australia, it was recorded for the first time in 1917 at Rutherglen in Victoria (Vic) (de Castella, 1917). The first recorded outbreak of the disease in Western Australia (WA) occurred in 1997 in a small planting of vines in the far north of the state. In the subsequent year, it was detected in widespread commercial viticulture in the Swan Valley production area, near Perth (McKirdy et al., 1999). The pathogen has since been found in all grape growing regions of WA. Since its introduction into European vineyards in the 1880?s, P. viticola has become one of the world?s most investigated grapevine pathogens. Many aspects its basic biology however remain unknown (Wong et al., 2001). Due to the recent detection of P. viticola in WA, little is known of the nature of strains of the pathogen in the state and their response to local environmental conditions. Much of the research concerning the influence of environmental factors on the development of P. viticola has been conducted in Europe e.g. parts of France and Germany. Due to significant differences in climatic conditions and a shorter selection time on the pathogen in WA, much of the information described in European studies may not be directly applicable to the grape downy mildew disease situation in WA. The focus of this thesis was to examine epidemiological aspects of P. viticola in the mediterranean climate of WA. The environmental conditions that could favour the development of epidemics by strains of the pathogen that have been detected in the state were determined. The existence of P. viticola ecotypes and genetic variation among strains from WA and the Eastern states of Australia was also investigated.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Thomas A. Evans, Dept. of Plant & Soil Sciences. Includes bibliographical references.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Resumo: A alface é a hortaliça folhosa de maior consumo no Brasil, no entanto a dificuldade em produzi-la vem aumentando, principalmente pela infestação das áreas de produção por Bremia lactucae, sendo necessário o monitoramento anual para utilização ou desenvolvimento de cultivares resistentes. Diante do exposto, os objetivos do presente trabalho foram: identificação de raças de B. lactucae no Estado de São Paulo, durante os anos de 2008, 2009 e 2010 e obtenção de linhagens de alface crespa resistentes às raças SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 e SPBl:07. Na primeira fase do estudo foram coletadas nos meses de agosto, setembro e outubro de 2008; agosto e setembro de 2009; e junho e julho de 2010 folhas de alface com esporângios de B. lactucae nos principais municípios produtores de alface do Estado de São Paulo. Após a multiplicação dos esporângios na cultivar suscetível Solaris, com posterior inoculação nas diferenciadoras, realizaram-se as avaliações, no mesmo dia do aparecimento da primeira esporulação na cultivar suscetível Cobham Green (DM 0). Na segunda fase do estudo realizou-se o cruzamento entre a cultivar Argeles e a linhagem JAB 4-13-7, bem como autofecundações, até a obtenção da geração F3, quando realizou-se o teste de resistência. Os dados permitiram concluir que: três novos códigos "Sextet" para Bremia lactucae ocorreram no Estado de São Paulo: 63/63/33/00, 63/63/02/00 e 63/31/03/00, denominados raças SPBl:05, SPBl:06 e SPBl:07, respectivamente; recomenda-se a utilização dos genes R-17, R-18 e R-38 como fontes de resistência ao míldio para o desenvolvimento de cultivares no Estado de São Paulo; e 19 progênies resistentes à B. lactucae, raças SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 e SPBl:07, apresentaramse homozigotas, e podem ser avançadas e avaliadas no processo de seleção / Abstract: Lettuce is the most consumed leafy vegetable in Brazil. Its production, nonetheless, is meeting with increasing difficulties mainly due to the infestation of producing areas with Bremia lactucae. Thus, the annual monitoring of B. lactucae races becomes of essential importance to use or development of resistant cultivars. The objectives of this work were identification of new races of B. lactucae occurring during the years of 2008, 2009 and 2010 in the state of São Paulo, Brazil, and development of resistant lettuce cultivars to races SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 and SPBl:07. In the first phase of experiment in August, September, and October of 2008; August and September of 2009; and June and July of 2010 lettuce leaf samples containing B. lactucae sporangia were collected in some of the lettuce producing areas of the state of São Paulo. After a multiplication procedure in which the susceptible lettuce cultivar 'Solaris' was used, the B. lactucae sporangia were inoculated in differentiating lettuce cultivars. Evaluations of the plants response were performed on the same day when plants of the susceptible Cobham Green (DM 0) cultivar showed signs of the first sporulation. In the second phase of experiment made the crossing between Argeles cultivar and JAB 4-13-7 line, and self pollination, to obtain the F3 generation, when made the resistant test. The data have identified: three new codes "Sextet" in the state of São Paulo: 63/63/33/00, 63/63/02/00 e 63/31/03/00. SPBl:05, SPBl:06 and SPBl:07 were the denomination proposed to races, respectively. The genes R-17, R-18, and R-38 are suggested to be used as source of resistance in the lettuce cultivars to state of São Paulo; and 19 resistant progenies to B. lactuae, races SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 and SPBl:07, shown homozygous, and they can be advanced and evaluated in the selection process / Orientadora: Leila Trevizan Braz / Coorientador: Tagli Dalpian / Coorientadora: Margarete Camargo / Banca: Pablo Forlan Vargas / Banca: Érika Auxiliadora Giacheto Scalopp / Banca: Rita de Cássia Panizzi / Banca: Joaquim Adelino de Azevedo Filho / Doutor

No description available.

Sporisorium reilianum is a basidiomycetous fungus that causes head smut in sorghum and maize. Infection requires the formation of a dikaryon between spores of compatible mating type and leads to a change from yeast-like to hyphal growth within the host plant. This switch is controlled through mating type loci. Among forty four different sorghum isolates of S. reilianum (SRS), including five different pathotypes, only three compatible pairs were detected, leading to the establishment of haploid cultures with three different “a locus” mating types, as verified by mRNA expression. Amino acid sequence comparison showed that the pheromone gene components of the a mating type loci of sorghum isolates (SRS) are highly similar to those of maize isolates (SRZ). Genetic diversity was measured using amplified fragment length polymorphism (AFLP) to compare isolates collected from the same and different hosts. AFLP analysis showed polymorphism both within and between SRS and SRZ isolates, with isolates from each host tending to show greater similarity. However, the study did not reveal patterns that could be associated with pathotype of sorghum isolates. A recent outbreak of sorghum downy mildew in Texas has led to the discovery of both metalaxyl fungicide resistance and a new pathotype, P6, in the causal organism, Peronosclerospora sorghi. To identify sources of resistance against P6, a total of 336 sorghum lines (245 mini-core lines from ICRISAT, India, 67 elite accessions from KSU, Kansas and 24 accessions from Texas) were used in a greenhouse study. Fifty two mini-core and 20 accessions from Kansas and 13 from Texas were recorded with ≤10% infection and characterized as resistant for further confirmation. Out of the 52 resistant mini-core accessions, 20 were photo-insensitive and showed 0 % infection. Eleven out of 20 from Kansas showed 0% infection. To quantify the genetic diversity among resistant accessions a high throughput ABI Prism 3100 DNA sequencing system was used for DNA fingerprinting with 60 Simple Sequence Repeat (SSR) markers representing all 10 sorghum linkage groups. Analysis of SSR patterns showed high diversity among the resistant sorghum accessions that were collected from different geographical regions and include the five defined races of Sorghum bicolor. Accessions that are not closely related were most likely to represent unique sources of genetic resistance to P. sorghi.

Thesis (Ph.D.) -- University of Adelaide, Dept. of Plant Pathology, 1966. / Typescript. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:33:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-21Bitstream added on 2014-06-13T18:45:40Z : No. of bitstreams: 1 castoldi_r_dr_jabo.pdf: 868883 bytes, checksum: 9fab3c7b39cbd568365fed7ff0addfc8 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A alface é a hortaliça folhosa de maior consumo no Brasil, no entanto a dificuldade em produzi-la vem aumentando, principalmente pela infestação das áreas de produção por Bremia lactucae, sendo necessário o monitoramento anual para utilização ou desenvolvimento de cultivares resistentes. Diante do exposto, os objetivos do presente trabalho foram: identificação de raças de B. lactucae no Estado de São Paulo, durante os anos de 2008, 2009 e 2010 e obtenção de linhagens de alface crespa resistentes às raças SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 e SPBl:07. Na primeira fase do estudo foram coletadas nos meses de agosto, setembro e outubro de 2008; agosto e setembro de 2009; e junho e julho de 2010 folhas de alface com esporângios de B. lactucae nos principais municípios produtores de alface do Estado de São Paulo. Após a multiplicação dos esporângios na cultivar suscetível Solaris, com posterior inoculação nas diferenciadoras, realizaram-se as avaliações, no mesmo dia do aparecimento da primeira esporulação na cultivar suscetível Cobham Green (DM 0). Na segunda fase do estudo realizou-se o cruzamento entre a cultivar Argeles e a linhagem JAB 4-13-7, bem como autofecundações, até a obtenção da geração F3, quando realizou-se o teste de resistência. Os dados permitiram concluir que: três novos códigos “Sextet” para Bremia lactucae ocorreram no Estado de São Paulo: 63/63/33/00, 63/63/02/00 e 63/31/03/00, denominados raças SPBl:05, SPBl:06 e SPBl:07, respectivamente; recomenda-se a utilização dos genes R-17, R-18 e R-38 como fontes de resistência ao míldio para o desenvolvimento de cultivares no Estado de São Paulo; e 19 progênies resistentes à B. lactucae, raças SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 e SPBl:07, apresentaramse homozigotas, e podem ser avançadas e avaliadas no processo de seleção / Lettuce is the most consumed leafy vegetable in Brazil. Its production, nonetheless, is meeting with increasing difficulties mainly due to the infestation of producing areas with Bremia lactucae. Thus, the annual monitoring of B. lactucae races becomes of essential importance to use or development of resistant cultivars. The objectives of this work were identification of new races of B. lactucae occurring during the years of 2008, 2009 and 2010 in the state of São Paulo, Brazil, and development of resistant lettuce cultivars to races SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 and SPBl:07. In the first phase of experiment in August, September, and October of 2008; August and September of 2009; and June and July of 2010 lettuce leaf samples containing B. lactucae sporangia were collected in some of the lettuce producing areas of the state of São Paulo. After a multiplication procedure in which the susceptible lettuce cultivar ‘Solaris’ was used, the B. lactucae sporangia were inoculated in differentiating lettuce cultivars. Evaluations of the plants response were performed on the same day when plants of the susceptible Cobham Green (DM 0) cultivar showed signs of the first sporulation. In the second phase of experiment made the crossing between Argeles cultivar and JAB 4-13-7 line, and self pollination, to obtain the F3 generation, when made the resistant test. The data have identified: three new codes “Sextet” in the state of São Paulo: 63/63/33/00, 63/63/02/00 e 63/31/03/00. SPBl:05, SPBl:06 and SPBl:07 were the denomination proposed to races, respectively. The genes R-17, R-18, and R-38 are suggested to be used as source of resistance in the lettuce cultivars to state of São Paulo; and 19 resistant progenies to B. lactuae, races SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 and SPBl:07, shown homozygous, and they can be advanced and evaluated in the selection process

Call number: LD2668 .T4 1978 H63 / Master of Science