Alice Maria Quezado-Duval

Outbreaks of bacterial spot caused by Xanthomonas gardneri on processing tomato in Central-West Brazil.

Severe epidemics of bacterial spot have been observed in central-west Brazil in fields of processing tomato. Several xanthomonads, Xanthomonas axonopodis pv. vesicatoria, X. vesicatoria, or X. gardneri, can cause the disease; therefore, attempts were made to identify the pathogen species present in this region. A total of 215 strains were obtained from 10 commercial areas in 1997, 1998, and 2000. The strains were characterized using pulsed-field gel electrophoresis (PFGE) and by their amylolytic and pectolytic activities. Representative strains from each PFGE haplotype then were tested for pathogenicity on tomato and pepper, carbon source utilization, and whole protein sodium dodecyl sulfate-polyacrylamide gel electrophoresis. rRNA sequence comparisons also were performed. All strains recovered from six fields were classified as X. gardneri, whereas X. vesicatoria and X. axonopodis pv. vesicatoria also were detected in the remaining four fields. Strains of X. gardneri, which could be grouped into two PFGE haplotypes, were unable to hydrolyze starch and pectate and to utilize gentiobiose and maltose. They expressed the β protein of 27 kDa and were pathogenic on tomato but variable on pepper. This is the first report of outbreaks of bacterial spot on tomato caused by X. gardneri.

Raças de Xanthomonas spp. associadas à mancha-bacteriana em tomate para processamento industrial no Brasil

ABSTRACT Races of Xanthomonas spp. associated to bacterial spot inprocessing tomatoes in Brazil The great genetic diversity of the causal agents of bacterial spotis the main problem to the development of tomato and pepper varietieswith durable resistance. Seventy two strains of Xanthomonas spp.collected from commercial fields of processing tomatoes in the statesof Goias, Minas Gerais, Pernambuco, and Bahia were classified inraces according to their reactions on differential genotypes of tomato(Walter, Hawaii 7998 and NIL 216) and Capsicum [ECW (EarlyCalwonder), ECW-10R, ECW-20R, ECW-30R and PI 235047].Bacterial suspensions (5 ´ 10 8 UFC/ml) were infiltrated in the abaxialleaf face of the plants at the three to five true-leaf stage. The plantswere then kept in a growth chamber at 28 o C and a 12-h light/darkphotoperiod. The response reactions were observed up to 36 hoursafter inoculation, depending on the genotype. Races T1P2, T1P8and T3 were identified in X. axonopodis pv. vesicatoria

Ocorrência e caracterização do complexo de espécies causadoras da mancha bacteriana do tomateiro no Alto Vale do Rio do Peixe, SC

Occurrence and characterization of the species complex causing tomato bacterial spot in “Alto Vale do Rio do Peixe”, SC, Brazil The aim of this study was to identify at the species level Xanthomonas strains causing tomato bacterial spot in the region of “Alto Vale do Rio do Peixe”, state of Santa Catarina, Brazil, as well as to determine their in vitro sensitivity to copper. Species were determined by similarity analysis of genomic profiles generated by BOX-PCR and sensitivity to copper was established using the CYE medium supplemented with copper sulfate at concentrations of 50, 100 and 200 μg/mL. Of the 44 isolates, 80% were identified as X. gardneri, 11% as X. perforans and 9% as X. vesicatoria. According to the response to copper, the isolates were divided into four classes (S, sensitive; MS, moderately sensitive; MI, moderately insensitive; I, insensitive). Regarding the sensitivity to copper, 98% of all isolates were sensitive at 200 μg/mL, suggesting that the recommended dosage of copper-based products registered for the crop may still provide effective control of the different bacterial species.

Xanthomonas perforans and X. gardneri associated with bacterial leaf spot on weeds in Brazilian tomato fields

Plants of Nicandra physaloides, Solanum americanum and Euphorbia heterophylla with leaf lesions have been found naturally grown among tomato plants in commercial fields in Brazil. Tomato bacterial spot was occurring in these fields. Xanthomonad-like isolates were obtained from affected weed leaf samples. These isolates were species identified using BOX-PCR and specific primers. Isolates from N. physaloides and S. americanum were identified as Xanthomonas perforans and that of E. heterophylla were identified as X. gardneri. Each of them was able to artificially infect and cause symptoms on the three weed species and tomato plants.

'BRS Tospodoro': a high lycopene processing tomato cultivar adapted to organic cropping systems and with multiple resistance to pathogens

ABSTRACT ‘BRS Tospodoro’ is a high lycopene tomato cultivar, which combines multiple disease resistance genes and desirable processing traits. This cultivar was found to be suitable for both conventional and organic crop systems. ‘BRS Tospodoro’ was obtained via backcross breeding using ‘Viradoro’ as recurrent parent and the inbred line ‘CNPH 1306’ as the donor of the Pto gene (resistance to Pseudomonas syringae pv. tomato race 0). ‘BRS Tospodoro’ has the Mi1-2 gene that controls resistance to root-knot nematodes ( Meloidogyne incognita , M. javanica, and M. arenaria ) as well as tolerance to populations of the aphid Macrosiphum euphorbiae (vector of Potyvirus species), and to whiteflies ( Bemisia tabaci ). ‘BRS Tospodoro’ has also the Sw-5b gene, which controls resistance to major Tospovirus species ( Groundnut ringspot virus , Tomato chlorotic spot virus , Chrysanthemum stem necrosis virus , and Tomato spotted wilt virus ). This cultivar is also resistant to Stemphylium solani and S. lycopersici

Intervals and Number of Applications of Acibenzolar-S-Methyl for the Control of Bacterial Spot on Processing Tomato

Acibenzolar-S-methyl (ASM) is a plant activator that triggers systemic acquired resistance that is labeled for use in Brazil for managing tomato bacterial spot. The aim of this study was to define the optimum relationship between interval and number of applications of ASM for the most efficacious control of bacterial spot on processing tomato. Four intervals between applications (4, 7, 10, and 14 days) and four application frequencies (4, 6, 8, and 10 applications) were evaluated in five trials performed between 2010 and 2011 in Brasília, Distrito Federal, and in Morrinhos, in the state of Goiás. Copper hydroxide (CH) was applied after ASM applications to complete 13 applications per growing season. Two check treatments were added: standard CH weekly applications and untreated. The following variables were evaluated: severity of bacterial spot, yield, percentage of ripe and rotten fruit, soluble solids content, and the benefit/cost ratio. Disease severity varied between treatments in three trials and yield varied in two trials. A greater number of applications resulted in a reduction of bacterial spot, and the ideal interval between applications was between 8 to 10 days. However, there was a reduction in yield with 10 ASM applications. The temporal effect of ASM applications on bacterial spot severity was evaluated under greenhouse conditions. Reduction in disease severity was observed up to 6 days following ASM application. Additionally, the weekly treatment of seven applications of ASM followed by six applications of CH was compared with a standard program of CH under commercial production conditions in Itaberaí, Goiás, where bacterial spot occurred naturally. The program with ASM and CH resulted in significantly less foliar disease severity than the standard program, which did not result in yield gains. In addition, no differences were detected between the two programs for soluble solids content, industrial yield, plant height, and percentage of ripe and rotten fruit.

Occurrence of Pseudomonas corrugata causing pith necrosis on tomato plants in Goiás, Brazil

RESUMO Ocorrencia de Pseudomonas corrugata causando necrose-da-medula em plantas de tomate em Goias, Brasil Identificou-se Pseudomonas corrugata associada a sintomas de necrose-da-medula em campo de producao de tomate para mesa localizado no municipio de Goianapolis, Goias, em 2006. A bacteria foi identificada por meio de PCR, utilizandose os iniciadores especificos PC5/1 e PC5/2. Realizou-se ainda testes fisiologicos e de patogenicidade que corroboraram na identificacao. No Brasil, P. corrugata havia sido relatada apenas em Sao Paulo e no Rio Grande do Sul.

Specific primers for Xanthomonas vesicatoria, a tomato bacterial spot causal agent

Xanthomonas vesicatoria is a member of the species complex associated with tomato bacterial spot. New and specific primers for X. vesicatoria were developed and validated. The primers were highly specific and detection was positive using purified bacterial DNA, bacterial suspensions and foliar lesions. These primers represent an additional tool for detection and identification of one of the species involved in this important disease complex.

Volume de aplicação e eficiência do controle químico da mancha bacteriana em tomateiro industrial

Hortic. bras., Brasília, v.35, n.3, July-September 2017 N Brasil, a cultura do tomate para processamento industrial vem crescendo, resultado do aumento da demanda dos derivados de tomate (Melo & Fonte, 2011). A produção brasileira nesse segmento concentra-se no estado de Goiás, onde as condições de clima, solo e topografia favorecem o cultivo (Silva-Junior et al., 2015). Nessa região, irrigam-se os cultivos de tomate para processamento por aspersão via pivôcentral, o que favorece a ocorrência de doenças que comprometem a produtividade e a qualidade dos frutos, com destaque para a mancha bacteriana (Quezado-Duval et al., 2004). Essa doença está associada a quatro espécies do gênero Xanthomonas: X. euvesicatoria, X. gardneri, X. perforans e X. vesicatoria. Nas principais regiões produtoras do Brasil, os primeiros estudos de epidemias da mancha bacteriana em tomate para processamento indicavam a prevalência da espécie X. gardneri (Quezado-Duval et al., 2004). Entretanto, segundo levantamentos mais recentes, a ocorrência de X. perforans tem aumentado e passou a prevalecer nos campos de tomate para processamento na região central do país (Araújo et al., 2016). Essas bactérias podem sobreviver em restos culturais, sementes, plantas daninhas e plantas voluntárias (Quezado-Duval & Lopes, 2010), o que dificulta a eliminação das fontes de inóculo. Até o momento, não há variedades comerciais desse segmento com níveis efetivos de resistência (Quezado-Duval et al., 2014). Assim, a ferramenta mais utilizada pelos produtores para o manejo da mancha bacteriana tem sido o controle químico. PONTES, NC; NASCIMENTO, AR; GOLYNSKI, A; MOITA, AW; MAFFIA, LA; OLIVEIRA, JR; QUEZADO-DUVAL, AM. 2017. Volume de aplicação e eficiência do controle químico da mancha bacteriana em tomateiro industrial. Horticultura Brasileira 35: 371-376. DOI http://dx.doi.org/10.1590/ S0102-053620170309