Some endophytes can synthesize molecules that elicit the induction of plant resistance to infection by pathogens. The objective of this study was to demonstrate that protein fractions 42 and 75 from Bacillus amyloliquefaciens and Bacillus pumilus were capable of acting as elicitors of induced resistance in tomato plants against Xanthomonas vesicatoria, following partial resolution by gel-filtration chromatography. Tomato plants sprayed with protein fractions 42 and 75 reduced, respectively, 63.5 and 56.6% of bacterial spot, compared with control plants. Additionally, these fractions promoted the increase of peroxidase (POX) and polyphenol oxidase (PPO) enzyme activities in treated plants. In SDS-PAGE stained with silver nitrate, protein fractions 42 and 75 appeared as simple bands with estimated molecular mass of 28 and 43 kDa, respectively. We report the partial characterization of two macromolecules synthesized by endophytic bacteria that act as elicitors of systemic resistance in tomato against X. vesicatoria.

O objetivo deste trabalho foi avaliar métodos, doses de manutenção e intervalos de aplicação do acibenzolar-S-metil (ASM) no controle da murcha bacteriana do tomateiro, bem como o seu efeito na densidade populacional do patógeno. Em ensaios conduzidos em casa-de-vegetação e câmara climatizada, o ASM foi aplicado via pulverização foliar e irrigado no solo. A inoculação de Ralstonia solanacearum ocorreu três dias após a segunda aplicação do produto. Para determinar a melhor dose de manutenção e época de aplicação, o ASM foi aplicado em três doses diferentes, com intervalos de aplicação de dez dias. Verificou-se redução significativa na severidade da doença em relação à testemunha não tratada independente do modo de aplicação do produto. As doses de manutenção proporcionaram reduções intermediárias na severidade da doença, diferindo entre si e dos demais tratamentos. Quanto às épocas de aplicação, não houve diferença significativa para o produto aplicado uma ou duas vezes após a inoculação da bactéria desafiante. No ensaio em câmara climatizada, observou-se aumento na altura das plantas tratadas com ASM e correlação negativa entre severidade da doença e crescimento das plantas. A aplicação de ASM reduziu a densidade populacional de R. solanacearum embora não tenha havido diferença significativa, comparada à testemunha.

The objective of this work was to evaluate application methods, maintenance doses, and application intervals of acibenzolar-S-methyl (ASM) on the control of tomato bacterial wilt, as well as its effect on pathogen population densities. In experiments carried out in a greenhouse and under controlled temperature, ASM was applied by two methods: foliar spray and soil drench. Ralstonia solanacearum was inoculated three days after the second application of ASM. To determine the best maintenance dose and application interval, ASM was applied using three different doses at ten-day intervals. There was a significant reduction in disease severity, regardless of the application method used. The maintenance doses of ASM provided intermediate severity reductions, differing from each other and from the other treatments. In relation to the number of applications, there was no significant difference when the product was applied one or two times after the inoculation of the challenging pathogen. The experiment conducted under controlled temperature showed an increase in the height of the tomato plants treated with ASM. Additionally, there was a negative correlation between disease severity and plant growth promotion. The application of ASM reduced the population densities of R. solanacearum, although there was no significant difference when compared to the control plants.

Avaliou-se o efeito da aplicação de extratos vegetais em induzir resistência à ferrugem, à cercosporiose e à mancha de Phoma em cafeeiro orgânico. O ensaio foi instalado em lavoura orgânica em Santo Antônio do Amparo, MG, cultivada com cafeeiros cv. "Acaiá MG-474-19", de quatro anos. Utilizou-se o delineamento em blocos casualizados com quatro repetições. Os tratamentos foram: 1. Testemunha pulverizada com Viça-café plus® aplicado em dezembro, janeiro e fevereiro; 2. Testemunha pulverizada com água; 3. Extrato aquoso de casca de fruto de café (CFC); 4. Extrato aquoso de folha de café com ferrugem (EFID); 5. Extrato aquoso de lobeira (Solanum lycocarpum) infectada com Crinipellis perniciosa (VLA) e 6. Extrato comercial de biomassa cítrica (Ecolife®). Os cafeeiros foram pulverizados mensalmente de 4 de março a 26 de junho de 2005. CFC e EFID reduziram a incidência da ferrugem, da cercosporiose e da mancha de Phoma comparativamente aos percentuais de doença observados nas testemunhas pulverizadas com água e com Viça-café. CFC reduziu a severidade da cercosporiose em 47%, comparado ao tratamento pulverizado com água. EFID e VLA reduziram a severidade da ferrugem em 31 e 27%. O melhor resultado foi proporcionado pelo EFID ao reduzir em 61% a incidência de Phoma em relação à testemunha pulverizada com água. O produto Ecolife® teve um desempenho intermediário aos melhores tratamentos e às testemunhas. EFID, CFC e VLA levaram a maior acúmulo de lignina nos tecidos foliares, diferenciando-se das testemunhas.

The effect of treatments with plant extracts on the induction of resistance against rust, brown eye spot and Phoma was evaluated in coffee grown in the organic crop system. The assay was set up in an organic crop in Santo Antônio do Amparo, MG, made up of four-year-old coffee trees cv. "Acaiá MG-474-19", in a randomized block design with four replicates. The treatments were: 1. Control, treated with Viça-café plus® sprayed in December, January and Febuary; 2. Control sprayed with water; 3. Aqueous extract of coffee fruit peel (CFC); 4. Aqueous extract of rust infected coffee leaf (EFID); 5. Aqueous extract of lobeira (Solanum lycocarpum) infected with Crinipellis perniciosa (VLA); 6. Commercial extract of citric biomass (Ecolife®). Coffee trees were sprayed monthly from March 4th to June 26th in 2005. CFP and EFID reduced the incidence of rust, brown eye spot and Phoma spot comparatively to the controls. CFC reduced severity of brown eye spot by 47% compared to the control sprayed with water. EFID and VLA reduced the severity of rust by 31 and 27%. The largest disease reduction was obtained by EFID with 61% reduction in incidence of Phoma spot compared to the control sprayed with water. Ecolife® had an intermediate performance, between the best treatments and the controls. EFID, CFC and VLA were associated with higher accumulation of lignin in the foliar tissues, differing from the negative and positive controls.