Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item Caracterização de isolados de Phytophthora infestans do Distrito Federal e de Goiás(Fitopatologia Brasileira, 2006-05) Ribeiro, Fabiana H. S.; Mizubuti, Eduardo S. G.; Reis, AiltonForam caracterizados 123 isolados de Phytophthora infestans obtidos de 21 lavouras de tomateiro e oito de batateira, em municípios do Estado de Goiás e Cidades Satélites de Brasília, no período de abril de 2001 a setembro de 2003. Os isolados foram caracterizados para os marcadores grupo de compatibilidade (123 isolados); isoenzima glucose 6-fosfato-isomerase (Gpi) (34 isolados) e resistência aos fungicidas mefenoxam (77 isolados) e metalaxyl (32 isolados de batateira), usando o método de disco de folhas. Todos os 78 isolados de tomateiro foram classificados no grupo de compatibilidade A1, enquanto os 45 de batateira foram do grupo A2. Os fenótipos para Gpi dos isolados de tomateiro (19) e de batateira (15) foram 86/100, típico da linhagem clonal US-1, e 100/100, típico da linhagen clonal BR-1, respectivamente. Quanto à resistência a mefenoxam, constataram-se isolados de tomateiro resistentes (36%), intermediários (48%) e sensíveis (16%). A maioria dos isolados de batateira foi classificada como sensível (82%) e apenas 9% de intermediários e resistentes. Dos isolados de batateira avaliados para resistência ao metalaxyl, 25% foram resistentes, 62% intermediários e 13% sensíveis. A população de P. infestans no Distrito Federal e no Estado de Goiás é constituída de duas linhagens clonais, com especificidade por hospedeiro.Item Bactérias endofíticas como agentes promotores do crescimento de plantas de tomateiro e de inibição in vitro de Ralstonia solanacearum(Ciência e Agrotecnologia, 2008-05) Barretti, Patrícia Baston; Souza, Ricardo Magela de; Pozza, Edson AmpélioA partir de 150 isolados de bactérias endofíticas obtidos de folhas, caules e raízes de tomateiros sadios, 53 destacaram-se quanto à habilidade em promover o crescimento de plantas de tomateiro (Solanum lycopersicum L.). Submetidos a uma nova seleção, os isolados UFV-E17, UFV-E22, UFV-E25, UFV-E26, UFV-E27, Bacillus cereus (UFV-E29), UFV-E49, UFLA 06-LS, UFLA 08-LS e UFLA 11-LS apresentaram maior promoção do crescimento. Avaliações semanais de altura e número de folhas e folíolos das plantas aconteceram durante 45 dias. Após a sexta avaliação, mensurou-se a área foliar e o peso da matéria fresca e seca da parte aérea e da raiz das plantas. O isolado UFV-E49 apresentou melhor resultado para altura, área foliar, número de folhas e peso da matéria fresca e seca, tanto da parte aérea quanto da raiz. Dos isolados selecionados, somente dois apresentaram efeito inibitório direto in vitro a Ralstonia solanacearum.Item Aggressiveness and host specificity of Brazilian isolates of Phytophthora infestans(Plant Pathology, 2004-08) Suassuna, N. D.; Maffia, L. A.; Mizubuti, E. S. G.The population of Phytophthora infestans in Brazil consists of two clonal lineages, US-1 associated with tomatoes and BR-1 associated with potatoes. To assess whether host specificity in these lineages resulted from differences in aggres- siveness to potato and tomato, six aggressiveness-related epidemiological components – infection frequency (IF), incu- bation period (IP), latent period (LP), lesion area (LA), lesion expansion rate (LER) and sporulation at several lesion ages (SSLA) – were measured on detached leaflets of late blight-susceptible potato and tomato plants. Infection frequency of US-1 was similar on potato and tomato leaflets, but IF of BR-1 was somewhat reduced on tomato. Incubation period was longer on both hosts with US-1, although this apparent lineage affect was not significant. Overall there was no host effect on IP. On potato, BR-1 had a shorter LP (110·3 h) and a larger LA (6·5 cm 2 ) than US-1 (LP = 162·0 h; LA = 2·8 cm 2 ). The highest LER resulted when isolates of BR-1 (0·121 cm 2 h −1 ) and US-1 (0·053 cm 2 h −1 ) were inoculated on potato and tomato leaflets, respectively. The highest values of the area under the sporulation capacity curve (AUSC) were obtained for isolates of US-1 inoculated on tomato leaflets (6146) and for isolates of BR-1 on potato leaflets (3775). In general, higher values of LA, LER, SSLA and AUSC, and shorter values of LP were measured when isolates of a clonal lineage were inoculated on their original host than with the opposite combinations. There is evidence that there are quan- titative differences in aggressiveness components between isolates of US-1 and BR-1 clonal lineages that probably con- tribute to host specificity of P. infestans populations in Brazil.Item A new bacterial disease of tomato in Viçosa, Minas Gerais state(Revista Ceres, 1995-05) Oliveira, José Rogério de; Miguel, Dulândula Silva; Romeiro, Reginaldo da SilvaIn 1991 it was observed a new disease of tomato in commercial plantations at the region of Viçosa, Minas Gerais State, Brazil. The disease shows up as necrotic lesions in leaves, either irregularly round or along leaf borders, initially small and increasing in size with age. These lesions are usually surrounded by a chlorotic halo. Drop exsudate tests indicated a bacterial etiology for the disease. From such lesions, it was consistently isolated a bacterium that gives rise to clear, opaque, regular, elevated and shinning colonies. Inoculations tests rendered HR in leaves of coffee, tobacco, bean and passion fruit as well as typical disease symptoms in tomato leaves. The bacterium is a single, regular, straight, Gram-negative, strictly aerobic rod, unable to use asparagine as sole C and N source, unable to produ-ce xanthomonadins, does not induce hipertrOphic growth in the host, produces a blue fluorescent pigment, grows easily in routine culture media and was positioned in the genus Pseudomonas, fluorescent group. Biochemical, staining and biological tests indicate the pathogen belongs to the species Pseudomonas syríngae pv. tomato,Item Synergism and negative interference during co-infection of tomato and Nicotiana benthamiana with two bipartite begomoviruses(Virology, 2009-03-12) Alves-Júnior, Miguel; Alfenas-Zerbini, Poliane; Andrade, Eduardo C.; Esposito, Débora A.; Silva, Fábio N.; Cruz, Ana Cláudia F. da; Ventrella, Marília C.; Otoni, Wagner C.; Zerbini, F. MuriloIn Brazil, at least eight begomoviruses including Tomato rugose mosaic virus (ToRMV) and Tomato yellow spot virus (ToYSV) infect tomatoes. ToYSV symptoms in tomato and Nicotiana benthamiana appear earlier and are more severe compared to those of ToRMV. We investigated the role of several factors in this differential adaptation. To analyze infection kinetics, a single leaf was inoculated and subsequently detached after different periods of time. Viral DNA accumulation was quantified in plants, viral replication was analyzed in protoplasts, and tissue tropism was determined by in situ hybridization. Results indicate that ToYSV establishes a systemic infection and reaches a higher concentration earlier than ToRMV in both hosts. ToRMV negatively interferes with ToYSV during the initial stages of infection, but once systemic infection is established this interference ceases. In N. benthamiana, ToYSV invades the mesophyll, while ToRMV is phloem-restricted. During dual infection in this host, ToYSV releases ToRMV from the phloem.