Isolation and identification of pathogen causing damping off at seedling stage of Trollius chinensis / 中国中药杂志

Trollius chinensis is a traditional Chinese medicinal material in China, the wild resource of T. chinensis are now exhausted, and commercial medicinal T. chinensis mainly depends on artificial cultivation. As one of the most severely happened diseases at the seedling period, damping off has been a serious threaten to the breeding of T. chinensis seedlings. However, no related research have been reported so far. So, the authors collected damping-off samples of T. chinensis in 2018 from seedling breeding nursery in Guyuan, Hebei province, and carried out study on taxonomic identification of the pathogen. Damping off occurs in the T. chinensis production area from mid-May to late June every year. At the beginning, brown lesions were observed on the basal stem, then the lesions circumferential expanded and constricted, and finally resulted in the fall and death of T. chinensis seedlings. Pathogenic isolate was growing rapidly on the PDA medium, well developed aerial mycelia were grey white at first, then turned brown gradually, and a great number of small dark brown sclerotia were developed in the middle and periphery of the colony. Mycelial diameter of the pathogen was about 7 to 10 μm, near right angle or acute angle branches, near branches with septa, branches and septa with constriction. After the healthy T. chinensis seedlings were inoculated by pathogenic isolate, damping-off was observed soon, and the symptom was as same as those observed in the field. Through homogenous blast, the rDNA-ITS sequence of the pathogenic isolate shown 99.49% to 99.84% homology with Rhizoctonia solani, R. solani AG-1 IC mycelium anastomosis group and Thanatephorus cucumeris, the sexual type of Rhizoctonia. Furthermore, obvious mycelial anastomosis phenomena were observed when the pathogenic isolate and R. solani AG-1 IC strain were confronting cultured. Based on the results above, the pathogenic isolate causing damping off of T. chinensis was identified as R. solani AG-1 IC mycelial anastomosis group. RESULTS:: in the present work have important significance for further research on basic biology of the pathogen and integrated control of damping off causing by it on T. chinensis.

Effectiveness of indigenous fluorescent pseudomonads in suppressing Rhizoctonia solani root rot disease and promoting plant growth in chilli seedlings

Aims@#This study aimed to isolate and evaluate the indigenous fluorescent Pseudomonas spp. with bio-control potential against Rhizoctonia solani and promoting growth in chilli seedlings. @*Methodology@#A total of 120 fluorescent bacterial were isolated from the healthy chilli rhizosphere soil from the seven major chilli cultivation localities in Terengganu, Malaysia. Only 115 Gram negative fluorescent isolates were further invitro screened for antagonistic activities against R. solani and plant growth-promoting properties. The 50 most effective fluorescent Pseudomonads antagonist against R. solani with minimum percentage inhibition of radial growth (PIRG) of 65% were selected. Hierarchical cluster analysis was further conducted with two dendrograms derived from SPSS Statistic 20 to facilitate the comparison between these 50 isolates for antagonistic and growth-promoting properties. A total of 40 fluorescent isolates within the most potential cluster were further selected and identified using 16S rRNA sequencing. Thirty four fluorescent isolates were identified as Pseudomonas spp. and six isolates as Burkholderia spp. The top 13 ranked fluorescent Pseudomonas spp. from the scoring index were evaluated for seed germination and vigor index in chilli seedlings. There was no significant difference in germination rate between fluorescent Pseudomonas inoculated with control. However, vigor index of chilli seeds pre-inoculated with fluorescent P. putida (B5C1), P. aeruginosa (B3C56) and P. putida (B5C7) were significantly increased with 4684.9, 4657.3 and 4401.0 over control (P ≤ 0.05).@*Conclusion, significance and impact of study@#These selected fluorescent isolates: P. putida (B5C1), P. aeruginosa (B3C56) and P. putida (B5C7) have the potential to be developed as biofungicide against R. solani and as growthpromoter in chilli production system.

Phytochemical profile and antifungal action of Anadenanthera colubrina extract on the quality of maize seeds

Maize (Zea mays L.) is among the most cultivated crops in the world and can be affected by several diseases, especially those transmitted by seeds. The study of alternatives to fungicides used for seed treatment has a promising field in essential oils. Thus, this study determined the phytochemical profile of the ethanolic extract from Anadenanthera colubrina (Vell.) Brenan and to evaluate its antifungal activity on the sanitary and physiological quality of maize seeds. The seeds used were of the Jaboatão cultivar, which were submitted to the following treatments: control (untreated seeds), commercial fungicide (dicarboximide) and A. colubrina extract at 200, 400, 600, 800, and 1,000 ppm. The seeds were subjected to sanitary and germination tests in a completely randomized experimental design. Phytochemical prospecting of A. colubrina extract indicated the presence of alkaloids, tannins, flavonoids and saponins, as well as the major compounds lupeol, gallic acid, ferulic acid, catechin and quercetin. The A. colubrina extract reduced the incidence of Aspergillus spp., including Aspergillus niger, Alternaria spp., Curvularia spp. and Fusarium spp. at all concentrations. The highest concentrations (800 and 1,000 ppm) of the A. colubrina extract reduced the incidence of Penicillium spp. and yielded an effective control of Rhizoctonia spp. The extract of A. colubrina did not present phytotoxic effect, guaranteeing the viability and vigor of maize seeds.

Fructosan form Paenibacillus kribbensis PS04 enhance disease resistance against Rhizoctonia solani and tobacco mosaic virus

BACKGROUND: Rice sheath blight (caused by Rhizoctonia solani) and tobacco mosaic virus are very important plant diseases, causing a huge loss in global crop production. Paenibacillus kribbensis PS04 is a broad-spectrum biocontrol agent, used for controlling these diseases. Previously, extracellular polysaccharides (EPS) from P. kribbensis PS04 had been purified and their structure was inferred to be fructosan. This study aimed to evaluate the effects of exogenous EPS treatment on plant­pathogen interactions. RESULTS: Plant defense genes such as phenylalanine ammonia-lyase, catalase, chitinase, allene oxide synthase, and PR1a proteins were significantly induced by exogenous EPS treatment. Moreover, subsequent challenge of EPSpretreated plants with the pathogens (R. solani or tobacco mosaic virus) resulted in higher expression of defenseassociated genes. Increased activities of defense-associated enzymes, total phenols, and flavonoids were also observed in EPS pretreated plants. The contents of malondialdehyde in plants, which act as indicator of lipid peroxidation, were reduced by EPS treatment. CONCLUSIONS: This study comprehensively showed that EPS produced from P. kribbensis PS04 enhances disease resistance in plants by the activation of defense-associated genes as well as through the enhancement of activities of defense-related enzymes.

Setting a rating scale for assess Rhizoctonia solani lesions on cotton, soybean and common bean seedlings / Ajuste de uma escala de notas para avaliar lesões de Rhizoctonia solani em plântulas de algodão, soja e feijão

Diseases incited by soilborne fungi are responsible for reducing the yield and cause significant impact to almost all crops. Among then, Rhizoctonia solani AG-4 is considered the most important in the cotton, common bean and soybean crops in Brazil. The use of diagrammatic scale or rating scales, as a tool to help in the quantification of the severity of a particular disease, is more common for foliar diseases. Considering the lack of a standardized, illustrated and easy-to-apply methodology for assessing the severity of R. solani lesions in cotton, soybean and common bean seedlings, a simple and precise rating scale was developed with the objective to fill this gap. The proposed scale shows four levels of disease severity, with the descriptions and illustrations for each type of lesion observed in the cotton, soybean and common bean seedlings. This developed scale was validated in many experiments and proved to be adequate for severity assessments of R. solani lesions on cotton, soybean and common bean seedlings.

Doenças causadas por fungos de solo reduzem a produtividade e impactam de forma significativa quase todas as culturas. Dentre elas, Rhizoctonia solani AG-4 é considerada a mais importante nas culturas de algodão, feijão e soja no Brasil. A utilização de escalas diagramáticas ou escalas de notas, como ferramenta para auxiliar na quantificação da severidade de uma determinada doença, é mais comum quando se trata de doenças foliares. Considerando a inexistência, até então, de metodologia padronizada, ilustrada e de fácil aplicação para a avaliação da severidade de lesões de R. solani em plântulas de algodão, soja e feijão, desenvolveu-se uma escala de notas, simples e precisa, com o objetivo de suprir essa lacuna. A escala proposta apresenta quatro níveis de severidade de doença, com descrições e ilustrações para cada tipo de lesão observada nas plântulas de algodão, soja e feijão. Essa escala foi validade em inúmeros experimentos, provando ser adequada para a avaliação da severidade de lesões de R. solani nas plântulas de algodão, soja e feijão

Effects of essential oils from two Lippia species on growth of phytopathogenic fungi / Efecto de los aceites esenciales de dos especies de Lippia sobre el crecimiento de hongos fitopatógenos

Chemical characterization of the essential oils of two Lippia species by GC-MS and NMR spectroscopy revealed that limonene (84.3%) and ß-caryophyllene (6.1%) were the most abundant components in Lippia turbinata while (6S,7S,10S)-trans-davanone (99.1%) predominated in Lippia integrifolia. Antifungal activity of the essential oils was determined by headspace volatile exposure assay against the fungal phytopathogenic Sclerotinia sclerotiorum, Sclerotium rolfsii and Rhizoctonia solani. The essential oil of L. turbinata showed potent antifungal activity against the panel of fungi tested while that the oil of L. integrifolia significantly inhibited the mycelial growth of S. rolfsii and R. solani.

La caracterización química de los aceites esenciales de dos especies de Lippia por cromatografía gaseosa-espectrometría de masas (CG-EM) y espectroscopia de RMN reveló que limoneno (84,3%) y ß-cariofileno (6,1%) fueron los componentes más abundantes de Lippia turbinata mientras que (6S,7S,10S)-trans-davanona (99,1%) predominó en Lippia integrifolia. La actividad antifúngica de los aceites esenciales se determinó por el ensayo de exposición a los vapores frente a los hongos fitopatógenos Sclerotinia sclerotiorum, Sclerotium rolfsii y Rhizoctonia solani. El aceite esencial de L. turbinata mostró una potente actividad antifúngica frente al panel de hongos ensayados, mientras que el aceite de L. integrifolia inhibió significativamente el crecimiento micelial de S. rolfsii y R. solani.

Evaluation of the fungitoxic activity of vegetal extracts on the mycelial growth of phytopathogens / Avaliação da atividade fungitóxica de extratos vegetais sobre o crescimento micelial de fitopatógenos

Although the productivity of common bean in Tocantins is economically favorable, it has been infected by various pathogens found in soil. Among the major diseases is the web blight and root rot caused by Rhizoctonia solani and collar rot caused by the fungus Sclerotium rolfsii. This study aimed to evaluate the fungitoxic activity of methanol extracts of eight plant species on the inhibition of mycelial growth of S. rolfsii and R. solani. The fungitoxic activities were carried out over the inhibition of mycelial growth by means in vitro assays. The extracts were applied in concentrations of 250, 500, 1000, 2500 e 5000 µg ml-1 in PDA culture medium. In bioassays, it was found the significant effect of plant, concentration and also their interaction on the antifungal activity of the extracts. However, some extracts showed no inhibition of mycelial growth of the pathogens studied. Among those who had higher inhibitions is the extract of Lantana trifolia, which inhibited the mycelial growth of S. rolfsii in all concentrations, being the same as 97% for the highest concentration. When the methanol extract of Piper amplum Kunth, inhibition of the highest concentration was 83% for S. rolfsii and 74% for R. solani. These results show the potential of methanolic extract of Lantana trifolia and Piper amplum Kunth in the control set of plant pathogens studied.

Apesar da produtividade do feijão comum no Tocantins ser economicamente favorável, o mesmo pode ser infectado por vários patógenos habitantes do solo, dentre as principais doenças encontra-se a mela e a podridão radicular causadas pelo fungo Rhizoctonia solani e a podridão do colo causada pelo fungo Sclerotium rolfsii. Este trabalho teve como objetivo avaliar a atividade fungitóxica dos extratos metanólicos de oito espécies vegetais sobre a inibição do crescimento micelial de Sclerotium rolfsii e Rhizoctonia solani. As atividades fungitóxicas foram realizadas perante a inibição do crescimento micelial por meio de ensaios in vitro, sendo os extratos aplicados nas concentrações de 250, 500, 1000, 2500 e 5000 µg ml-1 em meio de cultura BDA. Observou-se o efeito significativo dos fatores planta, concentração e também da interação destes sobre as atividades fungitóxicas. No entanto, alguns extratos não apresentaram inibição do crescimento micelial dos fitopatógenos estudados. Entre os que apresentaram maiores inibições encontra-se o extrato de Lantana trifolia, que inibiu o crescimento micelial do S. rolfsii em todas as concentrações, sendo o mesmo de 97% para a maior concentração. Já a concentração mais elevada do extrato metanólico de Piper amplum apresentou inibição de 83% sobre o crescimento micelial de S. rolfsii e 74% sobre o crescimento micelial de R. solani. Tais resultados evidenciam a potencialidade dos extratos metanólicos das folhas de Lantana trifolia e de Piper amplum no controle dos fitopatógenos estudados.

Characterization and pathogenicity of Rhizoctonia SPP. isolated from vegetable crops grown in greenhouses in Samsun province, Turkey / Caracterização e patogenicidade de Rhizoctonia SPP. isolada a partir de culturas vegetais crescidas em estufas na província de Samsun, Turquia

A total of one hundred and five isolates of Rhizoctonia belonging to 7 anastomosis groups (AGs) were obtained from the diseased roots and rhizosphere soils of bean, cucumber, eggplant, pepper and tomato plants grown in greenhouses in Samsun province (Black Sea region, Turkey) during the period 2011­2012. The isolates of Rhizoctonia spp. were examined for their cultural characteristics, anastomosis groups and pathogenicity. Of these, 83.8% were multinucleate Rhizoctonia solani (AG-2, AG-4, AG-5 and AG-6) and 16.2% were binucleate Rhizoctonia (AG-A, AG-E and AG-F). Sixty five of the isolates belonged to AG-4 which was the most frequent group (61.9%) in all greenhouses surveyed. Numbers of the isolates belonging to AG-2 (7.6%), AG-5 (6.7%) and AG-6 (7.6%) were 8, 7 and 8, respectively. Seventeen isolates recovered from greenhouses surveyed were identified as binucleate Rhizoctonia AG-A (1.9%), AG-E (6.7%) and AG-F (7.6%). All isolates of Rhizoctonia spp. tested for growth rates grew at temperatures of 10, 15, 20, 25 and 30°C, whereas they were completely inhibited at 5°C. The results of pathogenicity tests showed that the differences in virulence among isolates of Rhizoctonia spp. were statistically significant (P < 0.001). The tests on bean seedlings showed that the highest disease severity was caused by AG-4 isolates. The disease severity index (DSI) of the R. solani AG-4 isolates ranged from 3.2 to 3.8. In addition, the isolates of three AGs belonging to binucleate Rhizoctonia spp. were generally found to be moderately virulent (DSI 2.0­2.4).

Um total de cento e cinco isolados de Rhizoctonia pertencentes a 7 grupos de anastomose (AGs) foram obtidos a partir de raízes doentes e solos rizosféricos de plantas de feijão, pepino, berinjela, pimenta e tomate cultivados em estufas na província de Samsun (região do Mar Negro, Turquia) durante o período 2011-2012. Os isolados de Rhizoctonia spp. foram examinados por suas características culturais, grupos de anastomose e patogenicidade. Destes, 83,8% eram Rhizoctonia solani multinucleadas (AG-2, AG-4, AG-5 and AG-6) e 16,2% era Rhizoctonia binucleadas (AGA, AG-E and AG-F). Sessenta e cinco dos isolados pertenciam ao AG-4, que foi o grupo mais freqüente (61,9%) em todas as estufas pesquisadas. O número de isolados pertencentes a AG-2 (7,6%), AG-5 (6,7%) e AG-6 (7,6%) foi de 8, 7 e 8, respectivamente. Dezessete isolados recuperados de estufas pesquisadas foram identificados como Rhizoctonia binucleada AG-A (1,9%), AG-E (6,7%) e AG-F (7,6%). Todos os isolados de Rhizoctonia spp. testados para taxas de crescimento cresceram a temperaturas de 10, 15, 20, 25 e 30ºC, enquanto que foram completamente inibidos a 5ºC. Os resultados dos testes de patogenicidade mostraram que as diferenças de virulência entre os isolados de Rhizoctonia spp. foram estatisticamente significativas (P <0,001). Os testes em mudas de feijão mostraram que a maior severidade da doença foi causada por isolados AG-4. O índice de gravidade da doença (do inglês, disease severity index - DSI) dos isolados de R. solani AG-4 variou de 3,2 a 3,8. Além disso, os isolados de três AGs pertencentes à Rhizoctonia spp. binucleadas foram geralmente encontrados como moderadamente virulentos (DSI 2,0-2,4).

Control Efficacy of Streptomyces sp. A501 against Ginseng Damping-off and Its Antifungal Substance

Ginseng damping-off, caused by the fungal pathogens Rhizoctonia solani and Pythium sp., is a critical disease in ginseng seedling. In a continuing effort to find microorganisms with the potential of acting as a biocontrol agent against Rhizoctonia damping-off, we found that a Streptomyces sp. A501 showed significant antifungal activity against Rhizoctonia solani. In field experiment to test the efficacy of Streptomyces sp. A501 in controlling ginseng damping-off, the incidence of damping-off disease was meaningfully reduced when ginseng seeds were soaked in the culture broth of Streptomyces sp. A501 before sowing. To perform characterization of the antifungal compound, we isolated it from the culture broth of strain A501 through Diaion HP-20 and silica gel column chromatographies and preparative high-performance liquid chromatography. The structure of the antifungal compound was assigned as fungichromin by spectroscopic methods, mainly nuclear magnetic resonance and electrospray ionization-mass analysis.

Web blight (Thanatephorus cucumeris): a new disease on leaves of okra plants / Mancha areolada (Thanatephorus cucumeris): nova doença das folhas do quiabeiro

In an experiment on organic production of okra (Abelmoschus esculentus (L.) Moench) that was carried out from September 2013 to January 2014, in Manaus, Amazonas state, Brazil, we observed large chlorotic, necrotic, helical, discontinuous, dark or light-brown lesions with partial detachment of the injured area on the adaxial surface of leaves located in the median and basal portions of the plants. A whitish mycelium mantle covers the lesions on the leaves at the abaxial surface at high moisture conditions. Using morphological characteristics, Koch's postulates, and phylogenetic analyses of the ITS-5.8S rDNA region, we identified that the fungus causing the lesions on the okra leaves was Thanatephorus cucumeris (Frank) Donk (asexual stage of Rhizoctonia solani Kuhn of the anastomosis group AG-1 ID). This is the first report of T. cucumeris causing web blight on okra in Brazil, and probably in the world. So far, T. cucumeris was described on okra only on post-harvest pods rotting and seedlings' damping off.(AU)

Em um experimento sobre a produção orgânica do quiabeiro (Abelmoschus esculentus (L.) Moench), que foi instalado em Manaus, Amazonas, Brasil, no período de setembro de 2013 a janeiro de 2014, observou-se, na face adaxial do limbo foliar das folhas medianas e baixeiras, a ocorrência de lesões cloróticas e necróticas grandes, helicoidais, de coloração marrom escuro ou marrom claro e descontínuas, com desprendimento parcial da área lesionada. Na face abaxial, sobre as manchas, em condições de alta umidade, constatou-se a presença de um manto micelial esbranquiçado do patógeno, facilmente visível, recobrindo a área colonizada. Por meio da análise de características morfológicas, postulados de Koch e análise filogenética da região ITS-5.8S do rDNA do fungo isolado, identificou-se Thanatephorus cucumeris (Frank) Donk (fase assexuada Rhizoctonia solani Kuhn grupo de anastomose AG-1 ID) como o agente causal da doença. Este é o primeiro relato de T. cucumeris causando mancha foliar em quiabeiro no Brasil e, provavelmente, no mundo. Até então, sua ocorrência em quiabeiro estava restrita à podridão pós-colheita em frutos e tombamento de mudas.(AU)

Effect of organic amendment on stem canker and black scurf disease of potato (Solanum tuberosum) / Efeito da alteração orgânica sobre o cancro da haste e doença dos tuberculos pretos da batata (Solanum tuberosum)

An experiment was conducted at Tuber Crops Research Centre, BARI, Bogra during 2008-2009 to evaluate the organic amendment for controlling the stem canker and black scurf of potato. The different kinds of organic amendments were: T1 =Poultry refuse (PR) at 4 t ha-1, T2 =PR at 5 t ha-1, T3 =PR at 6 t ha-1, T4 =Mustard oil cake (MOC) at 300kg ha-1, T5 =MOC at 500kg ha-1, T6 =Neem oil cake (NOC) at 300kg ha-1, T7 =NOC at 500kg ha-1, T8 =Sawdust burning and T9 = Control. The experiment was laid out in a randomized complete block design (RCBD) with four replications. The organic amendment significantly influenced the disease incidence, yield attributes and yield of potato. The lowest disease incidence (17.5%) and per cent disease index (9.99) were found in T3 (poultry waste at 6 t ha-1). The minimum russet, deformed and Sclerotia infected tubers were also recorded in poultry waste at 6 t ha-1. The highest healthy tubers and tuber yield were found in the same treatment. Therefore, poultry manure 6 t ha-1 along with recommended dose of chemical fertilizer can be recommended to produce healthy tubers and maximum tuber yield of potato.

O experimento foi conduzido no (Centro de Pesquisa em Tubérculos ) Tuber Crops Research Centre, Bari, Bogra durante 2008-2009 para avaliar a alteração orgânica e controlar o cancro da haste e Black Scurf da batata. Os diferentes tipos de alterações orgânicas foram: T1 = Poultry recusar (PR) a 4 t ha-1, T2 = PR a 5 t ha-1, T3 = PR em 6 t ha-1, T4 = bolo de óleo de mostarda (MOC) em 300 kg ha-1, T5 = MOC em 500 kg ha-1, T6 = bolo de óleo de Neem (NOC) em 300 kg ha-1, T7 = NOC em 500 kg ha-1, T8 = queima de serragem e T9 = Controle. O delineamento experimental foi em blocos casualizados (RCBD) com quatro repetições. A alteração orgânica influenciou significativamente a incidência da doença, os atributos de rendimento e produtividade da batata. A menor incidência da doença (17,5%) por cento do índice de doença (9,99) foram encontrados em T3 (resíduos de aves a 6 t ha-1). O russet mínimo, deformado e Sclerotia tubérculos infectados também foram registrados em resíduos de aves a 6 t ha-1. O rendimento mais elevado tubérculos saudáveis e tubérculos foram encontrados no mesmo tratamento. Portanto, aviário 6 t ha-1, juntamente com a dose recomendada de fertilizante químico pode ser recomendado para a produção de tubérculos saudáveis e rendimento máximo dos tubérculos de batata.

Efecto antifúngico de cuatro mezclas de monoterpenos como alternativa para el control de Rhizoctonia solani Kün / Antifungal effect of four mixtures from monoterpenes like alternative by control of Rhizoctonia solani Kün

Rhizoctonia solani Kühn, es un patógeno de suelo, que causa enfermedades en un amplio rango de hospedantes de cultivos agrícolas. Las necesidades de reducir el uso indiscriminado de fungicidas químicos conllevan al estudio de otras alternativas menos agresivas al medio ambiente. Los monoterpenos presentes en los aceites esenciales de plantas, presentan una marcada actividad biocida y son compuestos que resultan menos perjudiciales desde el punto de vista ambiental. Se prepararon cuatro mezclas de monoterpenos (timol-entol, timolalcanfor, timol-citronelal y timol-1,8 cineol) con el objetivo de evaluar la actividad antifúngica in vitro sobre R. solani, mediante su efecto sinérgico. Se empleó el método de adición al medio de cultivo de cada una de las mezclas a concentraciones de: 0,5; 0,1; 0,05; 0,03 y 0,01 por ciento, partiendo de una solución madre al 10 por ciento en dimetilsufóxido (DMSO) al 5 por ciento. Se calcularon los porcentajes de inhibición y los resultados se analizaron estadísticamente. Se determinaron las dosis inhibitorias medias y se clasificaron la toxicidad de cada una de las mezclas en: inocua, ligera, moderada y tóxica a cada concentración. Las cuatro mezclas mostraron 100 por ciento de inhibición a las concentraciones de: 0, 5; 0, 1; 0,05 y 0,03 por ciento. A la menor concentración las mezclas de timol-mentol y timol-cineol fueron las de mayor efecto inhibitorio del crecimiento micelial de R. solani.

Rhizoctonia solani Kühn is a soil pathogen that causes diseases in a wide host range from agricultural crops. The need to reduce the indiscriminate use of chemical fungicide it has led to the study of other less aggressive environment alternatives. Monoterpenes, common components in plants essential oils, shows a maked biocide activity and are compounds less harmful from an environmental point of view. With the objective of evaluate the in vitro antifungal activity against R. solani, four binary monoterpenes mixtures (thymol-menthol, thymol-camphor, thymol-citronellal and thymol-1,8 cineol) with the objective of evaluate the in vitro antifungal activity against R. solani, four monoterpenes mixtures were prepared. The method of addition to culture media of each of the mixtures in concentrations of: 0, 5; 0, 1; 0, 05; 0, 03 and 0, 01 percent, from a stock solution to 10 percent in dimethylsulfoxide (DMSO) to 5 percent were used. The inhibition percentages were calculated and the results were statistically analyzed. Median inhibitory dose was determined and the toxicity of each mixture were classified in: harmless, light, moderate and toxic in each concentration. The four mixtures showed 100 percent of micelial growth inhibition in concentrations of 0, 5; 0, 1; 0,05 and 0,03 percent. The thymol-cineol and thymol-menthol mixtures had the higher inhibitory effect on micelial growth of R. solani at the lower concentration.

Potencial de preparados de cavalinha (Equisetum sp. ) na síntese de metabólitos de defesa em cotilédones de soja (Glycine max L. ) e o efeito sobre o crescimento de Rhizoctonia solani Kuhn, in vitro / Potential of horsetail (Equisetum sp. ) derivatives on the synthesis of defense metabolites using soybean ( Glycine max L. ) cotyledons and their effect on the in vitro growth of Rhizoctonia solani Kuhn

Foram desenvolvidos dois experimentos com objetivo de avaliar o potencial de preparados de cavalinha (Equisetum sp.) na síntese de metabólitos de defesa em cotilédones de soja (Glycinemax L.) e o efeito sobre o crescimento de Rhizoctonia solani, in vitro. O delineamento experimental utilizado para os experimentos foi inteiramente casualizado em esquema fatorial 3x5 (formas de extração x concentrações), com quatro repetições. As formas de extração foram extrato alcoólico, infusão e maceração, nas concentrações de zero; 1; 10, 20 e 40%. No primeiro experimento foi avaliada a indução de compostos de defesa vegetal em cotilédones de soja em resposta aos derivados a base de cavalinha, sendo quantificada a atividade da enzima fenilalanina amônia-liase (FAL), via espectofotometria, a fitoalexina gliceolina, e o teor de fenóis totais. No segundo experimento, in vitro, a unidade experimental foi uma placa de Petri, sendo os preparados de cavalinha incorporados ao meio BDA (Batata-dextrose e Agar) e avaliado o crescimento micelial de R. Solani. Os preparados de extrato alcoólico, infusão e maceração de cavalinha apresentaram capacidade de indução das fitoalexinas gliceolinas em cotilédones de soja, bem como, ativaram o metabolismo de compostos fenólicos. Entre os preparados, o extrato alcoólico e a maceração, se sobressaem sobre a infusão. Os preparados de extrato alcoólico, infusão e maceração de cavalinha em todas as suas concentrações inibem o crescimento do fungo R. solani, in vitro. .

Two experiments were carried out in the Federal Technological University of Paraná - Dois Vizinhos Campus - with the aim to evaluate the potential of horsetail (Equisetum sp.) derivatives for the synthesis of defense metabolites in soybean (Glycine max L.) cotyledons and their effect on the in vitro growth of Rhizoctonia solani. The experimental design was completely randomized in a 3 x 5 factorial design (extraction form x concentration), with four replications. The extraction forms were alcoholic extract, infusion and maceration and the concentrations tested were zero, 1, 10, 20 and 40%. In the first experiment, we evaluated the induction of plant defense in soybean cotyledons as a response to horsetail derivatives through spectrophotometry according to phytoalexin glyceollin, phenylalanine ammonia lyase enzyme activity (PAL) and total phenols. In the second experiment, in vitro, the experimental unit was a Petri dish, and the horsetail derivatives were incorporated into medium culture (potato dextrose agar), and we evaluated the mycelial growth of R. solani. The alcoholic extract, infusion and maceration of horsetail derivatives presented phytoalexin glyceolin induction in soybean cotyledons, in addition to activating the metabolism of phenolic compounds. Among the derivatives, the alcoholic extract and the maceration form of extraction were superior in relation to the infusion. The alcoholic extract, infusion and maceration of horsetail derivatives inhibited the in vitro growth of R. solani in all concentrations.

effect of neem [Azadirachta indica A. Juss] thevetia [thevetia peruviana [Pers.] K. Schum.] extracts inhibition of fungi growth causing cotton root-rot disease

The present showed the effect of Neem and Thevetia extract on growth of R. solani. The Stsdy Neem and Thevetia oil seed inhibited the growth of R. solani percentage of inhibition. Data indicated that the inhibition percentage of oil seed for the Neem was 79.3% and for Thevetia it was 75.2%. Ethanolic extract of leaves of Neem and Thevetia showed higher activity on the growth of R. solani at higher concentration. Applying ethanolic extract of the leaves of the Neem and Thevetia, revealed that the inhibition of the extract of leaves on the Neem was markedly higher than of Thevetia [68.9% versus 48.9%]

Antifungal Substances from Streptomyces sp. A3265 Antagonistic to Plant Pathogenic Fungi

In a previous study, we identified a Streptomyces sp., A3265, as exhibiting potent antifungal activity against various plant pathogenic fungi, including Botrytis cinerea, Colletotrichum gloeosporioides, and Rhizoctonia solani. This strain also exhibited a biocontrolling effect against ginseng root rot and damping-off disease, common diseases of ginseng and other crops. In this study, we isolated two antifungal substances responsible for this biocontrolling effect via Diaion HP-20 and Sephadex LH-20 column chromatography, medium pressure liquid chromatography, and high-performance liquid chromatography. These compounds were identified as guanidylfungin A and methyl guanidylfungin A by spectroscopic methods. These compounds exhibited potent antimicrobial activity against various plant pathogenic fungi as well as against bacteria.

First Report of Web Blight of Rosemary (Rosmarinus officinalis) Caused by Rhizoctonia solani AG-1-IB in Korea

Herein, we report the first occurrence of web blight of rosemary caused by Rhizoctonia solani AG-1-IB in Gangneung, Gangwon Province, Korea, in August 2014. The leaf tissues of infected rosemary plants were blighted and white mycelial growth was seen on the stems. The fungus was isolated from diseased leaf tissue and cultured on potato dextrose agar for identification. The young hyphae had acute angular branching near the distal septum of the multinucleate cells and mature hyphal branches formed at an approximately 90degrees angle. This is morphologically identical to R. solani AG-1-IB, as per previous reports. rDNA-ITS sequences of the fungus were homologous to those of R. solani AG-1-IB isolates in the GenBank database with a similarity percentage of 99%, thereby confirming the identity of the causative agent of the disease. Pathogenicity of the fungus in rosemary plants was also confirmed by Koch's postulates.

Atividade fungitóxica in vitro dos óleos essenciais de Lippia sidoides Cham., Cymbopogon citratus(D. C. ) Stapf. e de seus constituintes majoritários no controle de Rhizoctonia solani e Sclerotium rolfsii / Fungitoxicity in vitro of essential oils from Lippia sidoides Cham., Cymbopogon citratus (D. C. ) Stapf. and their major constituents in the control of Rhizoctonia solani and Sclerotium rolfsii

RESUMO O objetivo deste estudo foi avaliar o potencial fungitóxicos dos óleos essenciais de Cymbopogon citratus, Lippia sidoides, e de seus constituintes majoritários, sobre o crescimento micelial dos fitopatógenos Rhizoctonia solani e Sclerotium rolfsii. A caracterização química do óleo de L. sidoides demonstrou a presença do carvacrol (33,27%) e o 1,8-cineol (24,41%) como seus componentes majoritários. Enquanto que o citral (77,6%) foi o constituinte majoritário do óleo essencial de C. citratus. A avaliação do potencial fungitóxico dos óleos essenciais e de seus constituintes majoritários foi realizada por meio de ensaios in vitro, avaliando a inibição do crescimento micelial dos microrganismos. Ambos os óleos essenciais inibiram totalmente o crescimento micelial de R. solani na concentração de 400 µg mL-1. O crescimento micelial de S. rolfsii foi inibido pelo óleo essencial de C. citratus na concentração de 300 µg mL-1 e pelo óleo essencial de L. sidoides na concentração de 400 µg mL-1. Em relação aos constituintes majoritários, o 1,8-cineol não apresentou efeito fungitóxico nas concentrações avaliadas. No entanto, o carvacrol e o citral foram mais efetivos que os óleos essenciais havendo ausência de crescimento micelial de R. solani e de S. rolfsii nas concentrações de 200 µg mL-1 e 225 µg mL-1, respectivamente.

ABSTRACT The objective of this study was to evaluate the fungitoxic potentials of the essential oils of Cymbopogon citratus, Lippia sidoides, and of its major constituents, on the mycelial growth of phytopathogens Rhizoctonia solani and Sclerotium rolfsii. The chemical characterization of L. sidoides oil showed the presence of carvacrol (33.27%) and of 1,8-cineole (24.41%) as its major components, whereas citral (77.6%) was the major constituent of C. citratus essential oil. The evaluation of the fungitoxic potential of the essential oils and of its major constituents was performed through in vitro assays, the microorganisms mycelial growth inhibition. Both essential oils totally inhibited the mycelial growth of R. solani at 400 µg mL-1. Regarding the major constituents, the 1,8-cineole did not show fungitoxic effect at the concentrations evaluated. However, the carvacrol and the citral were more effective than the essential oils and there was no mycelial growth of R. solani and of S. rolfsii at the concentrations of 200 µg mL-1 and 225 µg mL-1, respectively.

Evolution of disease and potential biocontrol activity of Trichoderma SP. against Rhizoctonia solani on potato / Potencial do biocontrole por Trichoderma em relação à evolução da doença causada por Rhizoctonia solani em batata

Black scurf and stem canker disease cause by the fungal pathogen of Rhizoctonia solani and it is an economical important disease of potatoes in Bangladesh and throughout the world. This study evaluated the black scurf and stem canker disease development in potato and antagonistic activity of Trichoderma spp. against R. solani. The artificial infections were carried out using the inoculums of R. solani. The treatments (%inoculum) were: T1 (0% inoculum), T2 (5% inoculum), T3 (10% inoculum), T4 (20% inoculum), T5 (50% inoculum), and T6 (100% inoculum). The infection of stem canker and black scurf on progeny tubers increased with increase in inoculum levels. The highest disease incidence and severity was found in T6 (100% inocula). T6 showed the maximum black scurf infected tubers (russet, deformed and sclerotia). The lowest germination percentage, plant height and tuber yield were also obtained in the same treatment (100% inocula). Trichoderma spp reduced the growth of R. solani and the highest growth suppression was noted in isolate TM12. According to antagonistic activity, Trichoderma spp. reduced the growth of R. solani but was not able to stop the pathogen development. This finding showed management of this disease or R. solani invasion requires an integrated approach compared to Trichoderma single approach.

A rizoctoniose ou crosta negra causada por Rhizoctonia solani é a mais importante doença nos campos de batata em Bangladesh, bem como em várias regiões do mundo. Este trabalho avaliou o potencial do biocontrole com Trichoderma spp. e sua ação antagonista contra R. solani em batateira. Realizou-se as avaliações do potencial antagonosta usando inoculação artificial de R. solani. Os tratamentos (% de inóculo) foram: T1 (0% de inóculo), T2 (5% ), T3 (10%), T4 (20%), T5 (50%) , e T6 (100% de inóculo). A infecção de rizoctoniose na haste e crosta negra nos tubérculos aumentou proporcionalmente com o aumento do nível de inóculo. A maior incidência e severidade da doença ocorreu no tratamento 6 (100 % de inóculo), o qual apresentou maior quantidade de tubérculos infectados e deformados com escleródios em sua superfície. A menor porcentagem de germinação e produção de tubérculos também foi encontrada no tratamento 6, o qual também apresentou menor altura de planta. Trichoderma spp reduziu o crescimento de R. solani e a maior atividade de supressão do crescimento foi encontrada pelo isolado TM12. Foi detectada a atividade antagonista de Trichoderma spp. em reduzir o crescimento de R. solani, mas este não inibiu o crescimento total do patógeno. Conclui-se que o manejo da rizoctoniose da batateira por colonização de R. solani necessita táticas de manejo integrado em detrimento do uso isolado do manejo ou biocontrole com Trichoderma spp.

Comparison of different methods for total RNA extraction from sclerotia of Rhizoctonia solani

Background Rhizoctonia solani (teleomorph: Thanatephorus cucumeris) is one of the most important pathogens of rice (Oryza sativa L.) that causes severe yield losses in all rice-growing regions. Sclerotia, formed from the aggregation of hyphae, are important structures in the life cycles of R. solani and contain a large quantity of polysaccharides, lipids, proteins and pigments. In order to extract high-quality total RNA from the sclerotia of R. solani, five methods, including E.Z.N.A.™ Fungal RNA Kit, sodium dodecyl sulfate (SDS)-sodium borate, SDS-polyvinylpyrrolidone (PVP), guanidinium thiocyanate (GTC) and modified Trizol, were compared in this study. Results The electrophoresis results showed that it failed to extract total RNA from the sclerotia using modified Trizol method, whereas it could extract total RNA from the sclerotia using other four methods. Further experiments confirmed that the total RNA extracted using SDS-sodium borate, SDS-PVP and E.Z.N.A.™ Fungal RNA Kit methods could be used for RT-PCR of the specific amplification of GAPDH gene fragments, and that extracted using GTC method did not fulfill the requirement for above-mentioned RT-PCR experiment. Conclusion It is concluded that SDS-sodium borate and SDS-PVP methods were the better ones for the extraction of high-quality total RNA that could be used for future gene cloning and expression studies, whereas E.Z.N.A.™ Fungal RNA Kit was not taken into consideration when deal with a large quantity of samples because it is expensive and relatively low yield.

Efeito de compostos orgânicos sobre podridões radiculares no feijoeiro comum / Effect of organic compounds on root rots of common beans

Os fungos habitantes do solo, Rhizoctonia solani e Fusarium solani f.sp. phaseoli, constituem um complexo etiológico com interação sinérgica, responsável por perdas de produtividade de até 50% em feijoeiro. A matéria orgânica de diversas origens é utilizada na agricultura visando, entre outros motivos, estimular a atividade microbiana para limitar a atividade dos fitopatógenos habitantes do solo. O presente trabalho teve como objetivo avaliar o efeito de doses de compostos orgânicos sobre podridões radiculares causadas por R. solani e F. solani f.sp. phaseoli, em feijoeiro cultivar Pérola, em condições de campo. O delineamento experimental foi de blocos casualizados, em esquema fatorial de 2 x 6. Os compostos orgânicos à base de crotalária (Crotalaria juncea) e grama batatais (Paspalum notatum), associados com cama de frango, foram aplicados no sulco de plantio nas doses de 0, 20, 40, 80, 160 e 320 kg.ha-1. As avaliações de severidade foram realizadas, utilizando-se escala de notas. A maior severidade de F. solani f.sp. phaseoli em plantas de feijoeiro foi observada sob efeito da dose de 320 kg.ha-1 de crotalária + cama de frango e 80 kg.ha-1 para o composto à base de grama batatais + cama de frango. Para R. solani, os compostos orgânicos e doses não influenciaram a severidade de R. solani. A dose de 80 kg.ha-1, independente do composto orgânico, proporcionou a melhor produtividade.

The soil inhabiting fungi, Rhizoctonia solani and Fusarium solani f.sp. phaseoli, constitute an etiological complex with synergic interaction, responsible for up to 50% losses in common beans. Organic matter of diverse sources is used in agriculture to stimulate microbial activity limiting the activity of soil inhabiting plant pathogens, among other uses. This study evaluated the effect of organic compound doses on root rots caused by R. solani and F. solani f.sp. phaseoli, in common beans, cultivar Pérola, in field conditions. The experimental design was randomized blocks, as a 2 x 6 factorial. The organic compounds of Crotalaria juncea or Paspalum notatum, associated with poultry bedding, were applied in the planting furrow at the doses de 0, 20, 40, 80, 160 or 320 kg.ha-1. Evaluations of severity were done using a rating scale. Greater severity of F. solani f.sp. phaseoli in common bean plants were observed at the dose of 320 kg.ha-1 crotalaria + poultry bedding e 80 kg.ha-1 with paspalum compound + poultry bedding. The organic compounds and doses did not affect R. solani severity. The dose of 80 kg.ha-1, regardless of the organic compound, resulted in greater yield.