No description available.

Seed piece to plant transmission of the potato late blight pathogen, Phytophthora infestans, occurred with isolates of the clonal lineages US-8 in Oregon and US-11 in Washington in field trials. Average transmission rate across potato cultivars was 0.5 and 2.4% with US-8, and 0.8 and 1.0% with US-11 in 1999 and 2000, respectively. Transmission rate with US-8 was 2.3% for Russet Burbank (RB) in 1999 and 1.7, 0.7, 4.3, 7.6 and 0.5% for Bannock, Bzura, Ranger, Russet Norkotah (RN), and Umatilla, respectively, in 2000. Transmission rate with US-11 in 1999 was 0.5, 4.9 and 1.4% for RB, RN, and Shepody, respectively, and 1.7% for RB in 2000. Seedborne inoculum of both clonal lineages significantly affected stand establishment and plant vigor. With US-8, final emergence, emergence rate, and aerial biomass of cvs Kennebec, RB, RN, and Shepody were significantly lower than Bzura in 1999, whereas in 2000, these same responses in Chieftain, Bannock, Ranger, and Shepody were significantly lower than Bzura, Umatilla and RN. With US-11, these same response variables were significantly lower in Kennebec, RN and Shepody compared to Bzura and RB in 1999, and were significantly lower in Bannock, Chieftain, Ranger and Shepody compared to RB and Umatilla in 2000. Plant growth responses of cvs RB and RN grown from seed pieces infected with US-8 or US-11 were evaluated in greenhouse trials. RN was equally susceptible to both clonal lineages whereas RB was more resistant than RN to seedborne inoculum of US-11. Compared to RN its final emergence was higher, emergence rate was faster, aerial biomass was greater, and seed piece decay was lower. US-8 was more aggressive than US-11 on RB. US-8 caused a greater reduction in final emergence, emergence rate, and aerial biomass, and a greater increase in seed piece decay. The two clonal lineages were similar in their aggressiveness on RN. This is the first report of cultivar*clonal lineage*inoculum density interactions for plant growth responses of potato grown from seed pieces infected with P. infestans. / Graduation date: 2002

The limited specificity, sensitivity and multiplex capacity of detection techniques currently available for important seed-borne pathogens of tomato is a significant risk for the global tomato trade and production industry. These pathogens can be associated with seed at low concentrations but, due to their highly virulent nature, these low levels can be sufficient to infect germinating seedlings and spread to neighbouring plants and fields, potentially causing epidemics and economic losses. In this study, detection techniques currently available for phytodiagnostics were evaluated for the capacity to accurately detect and identify five agronomically important seed-borne pathogens of tomato: Pepino mosaic virus (PepMV), Tomato mosaic virus (ToMV), Clavibacter michiganensis subsp. michiganensis (Cmm), Xanthomonas campestris pv. vesicatoria and Pseudomonas syringae pv. tomato. A prototype diagnostic microarray was also designed in an attempt to develop a tool that could simultaneously detect these five seed-borne pathogens from a single sample. Viral detection based on serological techniques was rapid, accurate and reliable but only detected a single pathogen per assay and required supplementary bioassays to indicate the viability of detected viral pathogens. Selective media plating for bacterial detection demonstrated unreliable recovery of targeted bacteria from infected seed and leaf samples and required supplementary tests to validate the identity of presumptive positives. Assays were lengthy, laborious and sometimes too ambiguous for accurate diagnosis of bacterial pathogens. Nucleic acid-based technologies demonstrated improved sensitivity and specificity for detection of targets from pure culture, leaf and seed extracts, compared to conventional and serological methods, yet also required supplementary bioassays or media assays to validate the viability of detected pathogens. Amplification efficiency however, was affected by the presence of PCR inhibitors and despite positive detection, variable banding intensity in electrophoretic analysis of amplified products necessitated the use of reference cultures to validate diagnosis. The developed microarray incorporated 152 pathogen-specific and control probes to facilitate diagnosis and taxonomic classification of detected pathogens. The array was challenged with pure culture extracts of the five target pathogens, selected related and non-target, unrelated pathogens of tomato. Positive detection of each of the pathogens was demonstrated but the production of hybridisation signals was highly variable and extremely sensitive to minor technical differences. Each of the five pathogens were successfully detected in combination proving that different classes of seed-borne pathogens could be detected from a single sample using the developed microarray. This prototype microarray has good potential for phytodiagnostic screening of the five targeted pathogens, and further validation, optimisation and extension for testing tomato seed samples may facilitate incorporation of this array into standard diagnostic protocols.

Resumo: Dos vírus que infectam o maracujazeiro no Brasil, atualmente o Cowpea aphid borne mosaic virus (CABMV), é considerado fator limitante à cultura. Dependendo da velocidade de disseminação e idade com que as plantas são infectadas no campo, a cultura torna-se comercialmente improdutiva. O presente estudo teve como objetivo, avaliar a diversidade e a dinâmica populacional dos afídeos na região da Alta Paulista, SP e a possibilidade de transmissão do vírus pela semente. Assim, quatro locais (Leste e Oeste da cidade de Marília e Municípios de Ocauçú e Guaimbê) foram monitorados durante 24 meses com armadilhas amarelas de água do tipo Moericke. Constatou-se nas quatro regiões a predominância do gênero Aphis. Outras espécies coletadas foram Myzus persicae, Geopenphigus flocculosus, Brevicoryne brassicae, Rhopalosiphum spp, Dysaphis spp e Lipaphis erysimi. A flutuação populacional de formas aladas do gênero Aphis, caracterizou-se por apresentar maiores revoadas em maio, junho, agosto e setembro. As espécies de Aphis (A. fabae, A. gossypii, A. spiraecola) devem ser os principais vetores do CABMV na região. Plantios novos, ao lado de plantações infectadas, tornam-se infectadas em três meses. Nos testes de transmissão através de sementes, do total de 13056 semeadas oriundas de plantas doentes, germinaram 10592, e em avaliações visuais dois meses após a germinação, não foram observadas plantas sintomáticas, indicando a não transmissão pela semente. / Abstract: From the viruses were described infecting passionfruit plants in Brasil, and the Cowpea aphid borne mosaic virus (CABMV), is considered the most hazardous. Depending on the spread velocity of aphids and the age that the plants are infected, the crops doesn’t produce commercial fruits. The present study was designed to evaluate the diversity and dynamic population of aphids in the Alta Paulista, SP region and aspects of seed transmission. For this, four regions (East and West of Marília city, Guaimbê and Ocauçú) were monitored for 24 months using yellow water Moerick trap. The predominance of the genus Aphis was observed in the four evaluated areas. Other species founded in the area were: Myzus persicae, Geopenphigus flocculosus, Brevicoryne brassicae, Rhopalosiphum spp, Dysaphis spp and Lipaphis erysimi. The population curve of alate Aphis spp showed the highest frequency of flights during May, June, August and September. The Aphis spp (A. fabae, A. gossypii, A. spiraecola) probably is the most important vector of the CABMV in the region. New crops near old infected plants, were infected in three months. To evaluate properties of seed transmission, from 13056 collected from infected plants, 10592 were germinated and evaluated during two months for the presence of visual symptoms. No plants with simptoms were observed indicating no seed transmission. / Orientador: Marcelo Agenor Pavan / Coorientador: Valdir Atsushi Yuki / Banca: Renate Krause Sakate / Banca: Aloisio Costa Sampaio / Banca: Alexandre Levi R. Chaves / Banca: Hugo Kuniyuki / Doutor

Thesis (M.S. in plant pathology)--Washington State University, December 2007. / Includes bibliographical references.

No description available.

Made available in DSpace on 2014-06-11T19:32:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-02-06Bitstream added on 2014-06-13T18:48:04Z : No. of bitstreams: 1 narita_n_dr_botfca.pdf: 1059911 bytes, checksum: 143b0648ea6b08ccae020a5da8744b97 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Dos vírus que infectam o maracujazeiro no Brasil, atualmente o Cowpea aphid borne mosaic virus (CABMV), é considerado fator limitante à cultura. Dependendo da velocidade de disseminação e idade com que as plantas são infectadas no campo, a cultura torna-se comercialmente improdutiva. O presente estudo teve como objetivo, avaliar a diversidade e a dinâmica populacional dos afídeos na região da Alta Paulista, SP e a possibilidade de transmissão do vírus pela semente. Assim, quatro locais (Leste e Oeste da cidade de Marília e Municípios de Ocauçú e Guaimbê) foram monitorados durante 24 meses com armadilhas amarelas de água do tipo Moericke. Constatou-se nas quatro regiões a predominância do gênero Aphis. Outras espécies coletadas foram Myzus persicae, Geopenphigus flocculosus, Brevicoryne brassicae, Rhopalosiphum spp, Dysaphis spp e Lipaphis erysimi. A flutuação populacional de formas aladas do gênero Aphis, caracterizou-se por apresentar maiores revoadas em maio, junho, agosto e setembro. As espécies de Aphis (A. fabae, A. gossypii, A. spiraecola) devem ser os principais vetores do CABMV na região. Plantios novos, ao lado de plantações infectadas, tornam-se infectadas em três meses. Nos testes de transmissão através de sementes, do total de 13056 semeadas oriundas de plantas doentes, germinaram 10592, e em avaliações visuais dois meses após a germinação, não foram observadas plantas sintomáticas, indicando a não transmissão pela semente. / From the viruses were described infecting passionfruit plants in Brasil, and the Cowpea aphid borne mosaic virus (CABMV), is considered the most hazardous. Depending on the spread velocity of aphids and the age that the plants are infected, the crops doesn t produce commercial fruits. The present study was designed to evaluate the diversity and dynamic population of aphids in the Alta Paulista, SP region and aspects of seed transmission. For this, four regions (East and West of Marília city, Guaimbê and Ocauçú) were monitored for 24 months using yellow water Moerick trap. The predominance of the genus Aphis was observed in the four evaluated areas. Other species founded in the area were: Myzus persicae, Geopenphigus flocculosus, Brevicoryne brassicae, Rhopalosiphum spp, Dysaphis spp and Lipaphis erysimi. The population curve of alate Aphis spp showed the highest frequency of flights during May, June, August and September. The Aphis spp (A. fabae, A. gossypii, A. spiraecola) probably is the most important vector of the CABMV in the region. New crops near old infected plants, were infected in three months. To evaluate properties of seed transmission, from 13056 collected from infected plants, 10592 were germinated and evaluated during two months for the presence of visual symptoms. No plants with simptoms were observed indicating no seed transmission.