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 Genetic structure of the population of Alternaria solani in Brazil(Journal of Phytopathology, 2011-04) Lourenço Jr, Valdir; Rodrigues, Tatiana T. M. S.; Campos, Antonio M. D.; Bragança, Carlos A. D.; Scheuermann, Klaus K.; Reis, Ailton; Brommonschenkel, Sérgio H.; Maffia, Luiz A.; Mizubuti, Eduardo S. G.Understanding the genetic structure of the population of Alternaria solani (AS) is an important component of epidemiological studies of early blight, a severe disease that affects potato (Po) and tomato (To) worldwide. Up to 150 isolates obtained from both hosts were analysed with RAPD and AFLP markers to estimate the amount and distribution of genetic variability of AS in Brazil. Using RAPD, gene diversity (h=0.20) and scaled indices of diversity of Shannon (H′=0.66) and Stoddart and Taylor’s (G=0.31) for the Po population were higher than those of the To (h=0.07, H′=0.34, G=0.17). For AFLP, the statistics for the Po (h=0.17, H′=0.86, G=0.49) and To (h= 0.17, H′=0.85, G=0.36) populations were similar. For each RAPD and AFLP locus, the allele frequency for the overall population ranged from 0.006 to 0.988, and 0.007 to 0.993, respectively. Genetic differentiation was high (GST=0.41 and θ=0.59) and moderately high (GST=0.23 and θ=0.37) when estimated with RAPD and AFLP, respectively. Based on cluster analyses, there was strong evidence of association of pathogen haplotypes with host species. The null hypothesis of random association of alleles was rejected in the analysis of both RAPD (IA=13.1, P<0.001) and AFLP (IA=2.2, P<0.001) markers. The average number of migrants was estimated to be around one and two individuals per generation, using RAPD and AFLP, respectively. There was no correlation between genetic distance and geographical origin of AS haplotypes for RAPD (r=−0.07, P=0.84) and AFLP (r=−0.03, P=0.70). The AS population is clonal with high genetic variability, and there is genetic differentiation between the populations that affect To and Po.Item Biological control of eucalyptus bacterial wilt with rhizobacteria(Biological Control, 2015-01) Santiago, Thais R.; Rossato, Mauricio; Romeiro, Reginaldo S.; Mizubuti, Eduardo S. G.; Grabowski, CristhianThe antagonistic potential of 298 rhizobacteria obtained from the rhizosphere and rhizoplane of tomato and eucalyptus plants was assessed for the control of bacterial wilt of eucalyptus caused by Ralstonia solanacearum. Several tests were performed using tomato plants as a screening system to select efficient rhizobacteria. Different methods for antagonist delivery and pathogen inoculation were evaluated: (1) seeds were microbiolized (soaked for 12 h in a suspension of the antagonist propagules) and germinated seedlings had their roots immersed in the pathogen inoculum suspension; (2) seedlings originated from microbiolized seeds were transplanted to soil infested with R. solanacearum and (3) roots of seedlings were immersed in a suspension of propagules of the antagonist and subsequently in a suspension of R. solanacearum. Nine isolates (UFV-11, 32, 40, 56, 62, 101, 170, 229, and 270) were selected as potential antagonists to R. solanacearum as they suppressed bacterial wilt in at least one of the methods assessed. The selected antagonists were evaluated against two isolates of R. solanacearum using in vitro and in vivo (inoculated eucalyptus) tests. Isolates UFV-56 (Bacillus thuringiensis), UFV-62 (Bacillus cereus) and a commercial formulation of several rhizobacteria (Rizolyptus®) suppressed bacterial wilt in eucalyptus protecting the plants during the early stages of development.