No description available.

No description available.

No description available.

The species complex, Waitea circinata (WC) has been currently divided into five cultural types: var. circinata, var. oryzae, var. zeae, var. agrostis, and var. prodigus. These divisions are currently based on differences in their sclerotial morphology which have been supported by differences in their internal transcribed spacer region. Physiological differences such as optimal growth temperature, and morphological and pathogenic analyses as well as molecular biological techniques, were used to examine a broad WC collection coming from different geographic regions, and different susceptible hosts. The pathogenic examination showed that WC varieties are not host specific and can successfully infect both turfgrasses and cereals. Phylogenetic trees based on Neighbor-joining (NJ) and Maximum likelihood (ML) methods for three genomic regions (ITS, beta-tubulin, IGS1) showed support for only three of the five WC cultural types that have been described, namely Waitea circinata var. circinata, var. oryzae and var. zeae." / Waitea circinata varieties were characterized using molecular, morphological, physiological and pathological techniques. / Ontario Turfgrass Research Foundation, CONACYT (Ministry of Science from Mexico)

The aim of this study was to develop a genetic transformation system for the plant pathogenic fungus Rhizoctonia solani (teliomorph, Thanatephprus cucumeris Frank [Donk]). The availability of a transformation system would allow us to study gene exchange, epidemiology, and to use techniques such as gene disruption or gene silencing to investigate the role of fungal enzymes in pathogenesis. The approach adopted was to use Agrobacterium tumefaciens to transform the fungus as reports in the literature suggested that this was the most efficient and easiest method to use. As a preliminary test, Fusarium oxysporum was transformed using a binary vector (pBINAN) containing a hygromycin resistance gene under control of an ascomycete promoter and terminator. Hygromycin resistant transformants were obtained after co-incubation of fungal conidia with the bacterium. The presence of the transgene was confirmed by analysis of DNA. The number of transformants depended on the genetic background of the A tumefaciens. Strains AGLO or AGRO gave higher numbers of transformants compared to LBA4404. No transformants were obtained when the hygromycin gene was under control of a basidiomycete (pBINHL1), or a plant (CaMV35S) promoter. Since the basidiomycete promoter used in pBINHL1 originates from Ustilago maydis, the vector was tested by transformation of Ustilago cynodontis. Stable transformants of U cynodontis were obtained with this vector. A series of experiments were carried out on transformation of R. solani mycelium. Both the protoplast and the Agrobacterium transformation methods were tested. Parameters affecting protoplast production and regeneration were examined. Protoplast production varied with the age of the mycelium, with the osmotic stabilizer used, and with time of treatment with protoplasting enzymes. Regeneration of protoplasts was also affected by the osmotic stabilizer and the growth medium. Transformation of several isolates from different anastomosis groups (AG) was attempted by inducing protoplasts to take up DNA using polyethyleneglycol. Two plasmids were used; (1) pAN7-1 containing the resistance gene under control of an ascomycete promoter, and (2) pHL-1 in which the resistance gene is under control of a basidiomycete promoter. No transformants were obtained. Attempts were then made to transform mycelium and protoplasts using A tumefaciens. The experiments used both mycelium and protoplasts as the recipient. A number of small resistant colonies were obtained using binary plasmid (pBINHL1) in which mycelium was transformed with the resistance gene was driven by the basidiomycete promoter. On transfer to fresh medium these colonies would grow to about 2cm diameter, and then stop growing. On a second transfer to fresh medium they failed to show any growth. No resistant colonies were obtained from A. tumefaciens transformation of protoplasts. To improve transformation efficiency, a vector was constructed in which the hygromycin resistance gene was fused to an R solani laccase promoter sequence. No resistant colonies were obtained using this vector. Further experiments were carried out using a hygromycin resistance gene specially modified for expression in basidiomycetes by the insertion of artificial introns in the 5’ and 3’ untranslated regions, and a number of AT to CG conversions in the coding region. Most of the recipient isolates gave transformants with the unstable resistance phenotype. However, one AG 6 isolate gave transformants with a stable resistance phenotype. Of six transformants recovered from this isolate, five were shown by PCR and southern blotting to contain the transgene. In four of these transformants the resistance phenotype was stable in the absence of selection.

Thesis (Ph. D.)--University of Adelaide, Dept. of Soil Science, 1996. / Includes bibliographical references (leaves 184-209).

Thesis (M.S.) in Plant, Soil and Environmental Sciences--University of Maine, 2003. / Includes vita. Includes bibliographical references (leaves 79-84).

No description available.

Made available in DSpace on 2014-06-11T19:35:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-02Bitstream added on 2014-06-13T19:44:46Z : No. of bitstreams: 1 fenille_rc_dr_botfca.pdf: 795582 bytes, checksum: 759ea8f4173e60afb2c35123120e9e29 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Rhizoctonia solani representa um patógeno de importância econômica mundial nas áreas de cultivo da soja. Pode estar associado a vários sintomas como tombamento, podridão de raízes e hipocótilos e mela ou requeima da soja. No Brasil, os níveis de danos pela mela em soja variam de 31 a 60%, em lavouras dos Estados do Norte e Nordeste. R. solani está dividido em 14 grupos de anastomose (AG), que diferem quanto aos aspectos culturais, virulência e fisiologia. Desta forma, objetivou-se caracterizar AG de R. solani associados à soja no Brasil. Dentre 73 isolados analisados quanto a condição nuclear, 6 foram binucleados e 67 multinucleados. Os isolados multinucleados (R. solani) foram caracterizados através de anastomose de hifas, temperaturas limites para crescimento micelial, requerimento de tiamina, temperatura letal, produção de escleródios e comparações por RAPD. Através de anastomose de hifas, 4 isolados causadores de tombamento e podridão de hipocótilos foram caracterizados como AG-4. Análises de RAPD permitiram verificar que três, desses quatro isolados, pertenciam ao AG-4 HGII, e o outro ao AG-4 HGI. Através da fusão de hifas com AG-2-2 IIIB, crescimento a 35oC e auxotrofismo para tiamina, foi caracterizado um isolado, causador de tombamento e podridão de raízes e hipocótilos. Sessenta e dois isolados, causadores de mela, realizaram anastomose de hifas com o AG-1 IA apresentando em média 19,3 mm/dia de crescimento radial , formando escleródios tipo ‘sasakii’, característicos desse subgrupo. O enquadramento desses isolados no subgrupo IA foi confirmado pela análise de RAPD entre os isolados de R. solani de soja e padrões dos subgrupos do AG-1. Estruturas sexuais de Thanatephorus cucumeris (anamorfo R. solani) foram produzidas por um isolado do AG-1 IA, em condições de estufa biológica à temperatura de 28±1oC... . / Rhizoctonia solani represents a pathogen economically important in all soybean-growing areas in the world. It causes pre- and post-emergence damping-off, root and hypocotyl rot and foliar blight of soybean. Foliar blight has resulted in yield losses of 31-60% in North and Northeast of Brazil. R. solani is divided into 14 anastomosis groups (AG), that differ in cultural appearance, virulence, physiology and genetic. The aim of this study was to characterize R. solani isolates associated with soybean in Brazil. Among seventy-three Rhizoctonia isolates examined according to nuclear condition, six were binucleate and sixtyseven were multinucleate. The multinucleate isolates (R. solani) were characterized according to anastomosis group, limit temperature to radial growth, thiamine requirement, lethal temperature, sclerotia production and molecular marker RAPD. Four isolates, cause of damping-off and hypocotyl rot, belonged to AG-4. RAPD analysis showed that among four isolates of AG-4, three grouped with HGII and one belonged to HGI subgroup. Other isolate, cause of damping-off and root and hypocotyl rot, growth at 35oC in the dark and thiamine auxotrophic, belonged to AG-2-2 IIIB. Sixty-two isolates, cause of foliar blight, belonged to AG-1 IA. The mean radial growth rate was 19,3 mm/day and producing sasakii-type sclerotia, characteristic to the IA subgroup. RAPD analysis among R. solani AG-1 IA isolates of the soybean and anastomosis group testers, corroborate the characterization in IA subgroup. Perfect-stage Thanatephorus cucumeris (anamorph Rhizoctonia solani) was produced by one AG-1 IA isolate, in incubator at 28±1oC. The AG-4 and AG-2-2 IIIB isolates were pathogenic in soybean seedlings cv. ‘FT-Cristalina’, under greenhouse condition, causing damping-off and root and hypocotyl rot. The AG-2-2 IIIB isolate caused large lesions and cortex... (Complete abstract, click electronic address below).

Orientador: Nilton Luiz de Souza / Resumo: Rhizoctonia solani representa um patógeno de importância econômica mundial nas áreas de cultivo da soja. Pode estar associado a vários sintomas como tombamento, podridão de raízes e hipocótilos e mela ou requeima da soja. No Brasil, os níveis de danos pela mela em soja variam de 31 a 60%, em lavouras dos Estados do Norte e Nordeste. R. solani está dividido em 14 grupos de anastomose (AG), que diferem quanto aos aspectos culturais, virulência e fisiologia. Desta forma, objetivou-se caracterizar AG de R. solani associados à soja no Brasil. Dentre 73 isolados analisados quanto a condição nuclear, 6 foram binucleados e 67 multinucleados. Os isolados multinucleados (R. solani) foram caracterizados através de anastomose de hifas, temperaturas limites para crescimento micelial, requerimento de tiamina, temperatura letal, produção de escleródios e comparações por RAPD. Através de anastomose de hifas, 4 isolados causadores de tombamento e podridão de hipocótilos foram caracterizados como AG-4. Análises de RAPD permitiram verificar que três, desses quatro isolados, pertenciam ao AG-4 HGII, e o outro ao AG-4 HGI. Através da fusão de hifas com AG-2-2 IIIB, crescimento a 35oC e auxotrofismo para tiamina, foi caracterizado um isolado, causador de tombamento e podridão de raízes e hipocótilos. Sessenta e dois isolados, causadores de mela, realizaram anastomose de hifas com o AG-1 IA apresentando em média 19,3 mm/dia de crescimento radial , formando escleródios tipo 'sasakii', característicos desse subgrupo. O enquadramento desses isolados no subgrupo IA foi confirmado pela análise de RAPD entre os isolados de R. solani de soja e padrões dos subgrupos do AG-1. Estruturas sexuais de Thanatephorus cucumeris (anamorfo R. solani) foram produzidas por um isolado do AG-1 IA, em condições de estufa biológica à temperatura de 28±1oC... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: Rhizoctonia solani represents a pathogen economically important in all soybean-growing areas in the world. It causes pre- and post-emergence damping-off, root and hypocotyl rot and foliar blight of soybean. Foliar blight has resulted in yield losses of 31-60% in North and Northeast of Brazil. R. solani is divided into 14 anastomosis groups (AG), that differ in cultural appearance, virulence, physiology and genetic. The aim of this study was to characterize R. solani isolates associated with soybean in Brazil. Among seventy-three Rhizoctonia isolates examined according to nuclear condition, six were binucleate and sixtyseven were multinucleate. The multinucleate isolates (R. solani) were characterized according to anastomosis group, limit temperature to radial growth, thiamine requirement, lethal temperature, sclerotia production and molecular marker RAPD. Four isolates, cause of damping-off and hypocotyl rot, belonged to AG-4. RAPD analysis showed that among four isolates of AG-4, three grouped with HGII and one belonged to HGI subgroup. Other isolate, cause of damping-off and root and hypocotyl rot, growth at 35oC in the dark and thiamine auxotrophic, belonged to AG-2-2 IIIB. Sixty-two isolates, cause of foliar blight, belonged to AG-1 IA. The mean radial growth rate was 19,3 mm/day and producing sasakii-type sclerotia, characteristic to the IA subgroup. RAPD analysis among R. solani AG-1 IA isolates of the soybean and anastomosis group testers, corroborate the characterization in IA subgroup. Perfect-stage Thanatephorus cucumeris (anamorph Rhizoctonia solani) was produced by one AG-1 IA isolate, in incubator at 28±1oC. The AG-4 and AG-2-2 IIIB isolates were pathogenic in soybean seedlings cv. 'FT-Cristalina', under greenhouse condition, causing damping-off and root and hypocotyl rot. The AG-2-2 IIIB isolate caused large lesions and cortex... (Complete abstract, click electronic address below). / Doutor