Isolation, identification, and biocontrol of antagonistic bacterium against Botrytis cinerea after tomato harvest

ABSTRACT Tomato is one of the most important vegetables in the world. Decay after harvest is a major issue in the development of tomato industry. Currently, the most effective method for controlling decay after harvest is storage of tomato at low temperature combined with usage of chemical bactericide; however, long-term usage of chemical bactericide not only causes pathogen resistance but also is harmful for human health and environment. Biocontrol method for the management of disease after tomato harvest has great practical significance. In this study, antagonistic bacterium B-6-1 strain was isolated from the surface of tomato and identified as Enterobacter cowanii based on morphological characteristics and physiological and biochemical features combined with sequence analysis of 16SrDNA and ropB gene and construction of dendrogram. Effects of different concentrations of antagonistic bacterium E. cowanii suspension on antifungal activity after tomato harvest were analyzed by mycelium growth rate method. Results revealed that antifungal activity was also enhanced with increasing concentrations of antagonistic bacterium; inhibitory rates of 1 × 105 colony-forming units (cfu)/mL antagonistic bacterial solution on Fusarium verticillioides, Alternaria tenuissima, and Botrytis cinerea were 46.31%, 67.48%, and 75.67%, respectively. By using in vivo inoculation method, it was further confirmed that antagonistic bacterium could effectively inhibit the occurrence of B. cinerae after tomato harvest, biocontrol effect of 1 × 109 cfu/mL zymotic fluid reached up to 95.24%, and antagonistic bacterium E. cowanii has biocontrol potential against B. cinerea after harvest of fruits and vegetables.

Fusarium culmorum affects expression of biofilm formation key genes in Bacillus subtilis

Abstract It is known that there is correlation between biofilm formation and antagonistic activities of Bacillus subtilis strains; but, the mechanism of this correlation is not clear. So, the effect of the plant pathogen (Fusarium culmorum) on the biofilm formation in a B. subtilis strain with high antagonistic and biofilm formation activities was studied. The expression of sinR and tasA genes involved in the biofilm formation was studied in both single culture of bacterium (B) and co-culture with F. culmorum (FB) using real-time PCR. The results revealed that the expression of the sinR gene in both B and FB conditions was continuously decreased during the biofilm formation period and, after 24 h (B4 and FB4), it reached 1% and 0.3% at the planktonic phase (B1), respectively, whereas the expression of the tasA was continuously increased and was 5.27 and 30 times more than that at the planktonic phase (B1) after 24 h, respectively. So, the expression reduction rate for sinR (3 times) and the expression increasing rate for tasA (6 times) were significantly higher in FB conditions than the B ones. The relative expression of sinR in FB1 (planktonic phase), FB2 (8 h), FB3(12 h), and FB4 (24 h) times was 0.65, 0.44, 0.35, and 0.29, whereas the tasA gene expression was 2.98, 3.44, 4.37, and 5.63-fold of the one at coordinate time points in B conditions, respectively. The significant expression reduction of sinR and increase of tasA confirmed that the presence of pathogen could stimulate biofilm formation in the antagonistic bacterium.

Associação entre resiliência e qualidade de vida relacionada à saúde bucal em idosos / Association between resilience and quality of life related to oral health in the elderly

OBJETIVO: Avaliar a associação entre resiliência e qualidade de vida relacionada à saúde bucal, por meio de uma abordagem hierárquica baseada em um modelo teórico conceitual em uma coorte de idosos do Rio Grande do Sul. MÉTODOS: Foi conduzido um estudo transversal aninhado a um estudo de coorte, em 2008. Foram avaliados 498 idosos de Carlos Barbosa, Rio Grande do Sul. As medidas avaliadas foram sociodemográficas, comportamentos de saúde, qualidade de vida relacionada à saúde bucal, medida pelo Oral Health Impact Profile (OHIP-14), Escala de Resiliência e CPOD. A associação entre o potencial de resiliência e os impactos na percepção de saúde bucal relacionados à qualidade de vida foi verificada por meio de regressão binomial negativa. Razões das médias (RM) são apresentadas com seus intervalos de confiança de 95% (IC95%). RESULTADOS: Maiores médias do OHIP foram encontradas entre mulheres (6,7 ± 6,3; p = 0,011), moradores da zona rural (7,3 ± 6,7; p = 0,004) e solteiros (8,0 ± 6,3; p = 0,032). O modelo final da análise multivariada mostrou que ser morador da zona rural (RM = 1,32; IC95% 1,06 - 1,65) e casado (RM = 1,36; IC95% 1,07 - 1,72) foram variáveis independentemente associadas à qualidade de vida relacionada à saúde bucal. Não houve associação entre resiliência e qualidade de vida relacionada à saúde bucal. CONCLUSÃO: Os resultados sugerem que variáveis sociodemográficas estão associados à qualidade de vida relacionada à saúde bucal. A hipótese de que a resiliência pudesse exercer um papel importante no desfecho não foi confirmada. .

OBJECTIVE: To evaluate the association between psychological resilience and oral health related to quality of life through a hierarchical approach based on a conceptual theoretical model in a cohort of elderly residents in Rio Grande do Sul, Brazil. METHODS: We conducted a cross-sectional study nested in a cohort study in 2008. We evaluated 498 elderly residents in Carlos Barbosa, Rio Grande do Sul. The measures included sociodemographic questionnaire, health behavior, quality of life related to oral health (OHRQOL), measured by the Oral Health Impact Profile (OHIP-14), Resilience Scale, and DMFT. The association between resilience and potential impacts on perceptions of oral health-related quality of life was assessed through negative binomial regression. Mean ratios (MR) are presented with 95% confidence intervals (95%CI). RESULTS: Higher means of OHIP were found in women 6.7 ± 6.3; p = 0.011), in rural dwellers (7.3 ± 6.7; p = 0.004) and singles (8.0 ± 6.3; p = 0.032). The final model of multivariate analysis showed that being a rural dweller (MR = 1.32; 95%CI 1.06 - 1.65) and being married (MR = 1.36; 95%CI 1.07 - 1.72) were independently associated with OHRQOL. There was no association between resilience and OHRQOL. CONCLUSION: The results suggest that factors such as sociodemographic variables are associated with OHRQOL. The hypothesis that resilience might play a role in the outcome has not been confirmed. .

Comportamento do maracujazeiro amarelo, variedade Afruvec, ante uma população de Fusarium solani, agente causal da podridão do colo / Behaviour of yellow passion fruit, Afruvec variety, in relation to a population of Fusarium solani, causal agent of collar rot

O objetivo do presente trabalho foi verificar o comportamento do maracujazeiro amarelo, variedade Afruvec, ante uma população de Fusarium solani, obtida desse mesmo hospedeiro. O delineamento adotado foi o de blocos ao acaso, contendo dez tratamentos (nove isolados e tratamento testemunha), com quatro repetições, sendo cada parcela representada por um vaso contendo uma planta. Um disco do meio de cultura, colonizado com cada isolado do fungo, foi inoculado no colo ferido das plantas da variedade Afruvec, dois meses após a semeadura. Avaliou-se a patogenicidade, a incidência (número de plantas mortas) e a severidade da doença (comprimento da lesão no colo), até os sessenta dias após a inoculação. A variedade Afruvec foi suscetível ao fungo e apresentou variabilidade quanto à incidência e severidade da doença diante dos diferentes isolados. A população do fungo apresentou variabilidade em relação à agressividade. Com a evidência de diversidade genética na população do fungo, recomenda-se, também, nos testes de seleção de materiais ao patógeno, a avaliação desses materiais em diferentes localidades com histórico da doença ou inoculação com uma mistura de isolados do fungo, a fim de se conhecer a resistência ampla do genótipo ao patógeno.

The objective of the present work was to verify the behavior of yellow passion fruit, Afruvec variety, in relation to a population of Fusarium solani, obtained from this crop. The experimental delineation was random blocks, containing 10 treatments [9 isolates and 1 control treatment], with 4 repetitions, each plot being represented by a vase containing a plant. A disk of culture medium colonized by each isolate of the fungus was inoculated in the wounded collar region of the plants of the Afruvec variety two months after sowing. The appraised parameters were: the pathogenicity, the incidence (number of dead plants) and the severity of the disease (length of the lesion in the collar region), until 60 days after inoculation. The Afruvec variety was susceptible to the fungus and also presented variability as to the severity of the disease and incidence in relation to the different isolates. The population of the fungus showed variability in regard to aggressiveness. In light of the evidence of genetic diversity in the F. solani population, it is also suggested, in the tests of selection of materials to the pathogen, that these materials should be evaluated in different places with a history of the disease or inoculation with a pool of isolates of the fungus, in order to know the wide resistance of the genotype to the pathogen.

Plant defense induced in in vitro propagated banana (Musa paradisiaca) plantlets by Fusarium derived elicitors.

Perception of microbial signal molecules is part of the strategy evolved by plants to survive attacks by potential pathogens. To gain a more complete understanding of the early signaling events involved in these responses, we used fungal components of Fusarium under in vitro condition and checked the rise in signal molecule, salicylic acid (SA), and marker enzymes in defense reactions against the pathogen. SA level increased by 21 folds in elicitor treated plantlets as compared to that of control plantlets and there was marked increase in phenylalanine ammonia-lyase(PAL), peroxidase(POX), polyphenol oxidase(PPO) along with higher total phenolic content. Present results indicated that use of fungal components had successfully induced systemic resistance in in vitro cultured banana plantlets.

Biological control of Fusarium wilt of pigeonpea Cajanus cajan (L.) Millsp with chitinolytic Alcaligenes xylosoxydans.

Alcaligenes xylosoxydans protected pigeonpea from Fusarium wilt in a pot experiment and field trials. When seeds of pigeonpea (C. cajan) were treated with A. xylosoxydans and sown in soil infested with Fusarium, the incidence of wilt was reduced by 43.5% and resulted in 58% higher grain yield. The antifungal activity of A. xylosoxydans was based on chitinase production and was comparable in efficacy to commercial antifungal agents such as benlate, monitor WP, thiram and bavistin.

Lung injury by furanoterpenoids isolated from Fusarium solani infected sweet potato, Ipomea batatas.

Intraperitoneal administration (1 mg/kg body/wt./day for 21 days) of crude extract of furanoterpenoids, isolated from F. solani damaged I. batatas caused pulmonary oedema in albino rats. The elevated broncho alveolar lavage (BAL) angiotensin converting enzyme (ACE), lactate dehydrogenase (LDH) and protein levels indicated lung damage. The estimation of pulmonary extracellular surfactant phospholipids showed an alteration in various phospholipid fractions.

Interacción de distintos factores sobre la biosíntesis de tricotecenos por cepas de fusarium / Interaction of differents factors on the biosynthesis of trichothecenes by fusarium strains

Se estudió la influencia del medio de cultivo, la cepa, el tiempo y la temperatura sobre la biosíntesis de tricotecenos en cinco cepas de Fusarium toxicogénicas. Se analizó también el efecto combinado de dichas variables. Para la evaluación del grado de toxicidad se utilizó el micrométodo biológico basado en la inhibición que ejercen los tricotecenos sobre la germinación de semillas de Lepidium sativum.(5). Analizando el efecto de las variables por separado, se constató que existe un 99% de probabilidad (*=0.01) de que el medio de cultivo, la cepa y la temperatura incidan en la biosíntesis de tricotecenos; en tanto que para el tiempo, y dentro del rango estudiado, la probabilidad es del 95% (*=0.05). En cuanto a la interacción de las variables, existe un 99% de probabilidad (*=0.01) de que el efecto combinado de medio de cultivo-tiempo-temperatura y medio de cultivo-cepa-temperatura incidan en el grado de toxicidad