The antifungal potential of volatile organic compounds (VOCs) produced by actinobacterial strains Streptomyces sp. (ACTB-77) and Amycolatopsis sp. (ACTB-290) from the rhizosphere of Caatinga plants against Colletotrichum musae was investigated. VOCs produced by these microorganisms (axenic and co-culture) were investigated using headspace-solid phase micro-extraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). Although no exclusive VOC peaks were observed in the co-culture with ACTB-77, the same experiment involving ACTB-290 yielded five new peaks, including two identified alcohols, suggested as bioreductive products of the corresponding ketones by the fungus. Statistical analysis revealed that co-culture ACTB-77/C. musae has a closer similarity to the fungus than to the actinobacteria, while the co culture ACTB-290/C. musae showed closer similarity to the actinobacteria. These confirmed the more pronounced antifungal activity of the ACTB-290 strain, as observed in the fungus growth inhibition experiments. The antifungal activity of ACTB-290 was associated to its sulfur-containing metabolites, while linalool was suggested as responsible for the ACTB-77 activity.

O fungo fitopatogênico Lasiodiplodia theobromae, isolado de goiaba, foi cultivado em arroz por 32 dias à temperatura ambiente. Extração com CH2Cl2:MeOH (3:7), seguido de fracionamento cromatográfico do extrato forneceu o esteróide ergosterol. Da cultura fúngica em meio de Czapeck por 40 dias à temperatura ambiente, foram isolados a isocumarina cis-4-hidroximeleína e um sesquiterpeno do tipo eremofilano. O sesquiterpeno eremofilano está sendo descrito pela primeira vez na literatura. Este é o primeiro relato do isolamento de um sesquiterpeno eremofilano para o gênero Lasiodiplodia.

The phytopatogenic fungus Lasiodiplodia theobromae, isolated from guava, was cultivated in rice for 32 days at room temperature. Extraction with CH2Cl2:MeOH (3:7), followed by chromatography fractionation of the extract provided ergosterol. From the fungus culture in Czapeck medium for 40 days at room temperature, were isolated isocoumarin cis-4-hydroxymeleine and an eremophilane-type sesquiterpene. The latter compound is being reported for the first time in the literature. Also, this is the first time that an eremophilane sesquiterpene is described for Lasiodiplodia genus.

A new post-harvest disease of coconut (Cocos nucifera) was recently detected in fruits exported to European countries. The main symptoms are the blacking and cracking of basal parts of the fruits. Water oozing may occurs as the infection progresses. The fungus Lasiodiplodia theobromae has been frequently isolated from the lesions. Inoculation tests proved that this pathogen is the causal agent of the coconut fruit basal rot. This is the first occurrence of this post-harvest disease in Brazil.

Em regiões tropicais e de temperaturas elevadas, Macrophomina phaseolina é agente de podridão em raízes, caule, ramos, e frutos em mais de 500 espécies de plantas cultivadas.Entretanto, pouco se sabe acerca da influência da temperatura e da umidade sobre a germinação dos microescleródios desse fungo. O objetivo deste trabalho foi estudar o efeito da interação temperatura-tensão de água na areia sobre a germinação dos microescleródios do fungo. Os trabalhos foram conduzidos em condições de laboratório, tendo sido realizados em duas etapas. Em um primeiro experimento, avaliou-se a interação de cinco temperaturas com duas tensões de água. Os resultados obtidos subsidiaram um segundo experimento no qual avaliou-se a interação de duas temperaturas com seis tensões de água no substrato. O delineamento experimental para ambos experimentos foi o inteiramente casualizado com quatro repetições, em esquema fatorial, com arranjo combinatório 5x2 e 2x6, respectivamente, para o primeiro e segundo experimentos. Os resultados mostraram (P<=0,05) que os maiores percentuais de germinação ocorreram às temperaturas de 30 ºC e 33 ºC. Na tensão de água de -1.500 kPa ocorreu germinação em todas as temperaturas testadas. A tensão de água de -80 kPa tendeu a proporcionar o maior percentual de germinação, embora não tenha diferido das tensões de -8, -300 e -1.500 kPa. Os microescleródios não germinaram em areia seca ao ar, porém germinaram em 0 kPa, embora em menor percentual que a -8, - 80, -300 e -1.500 kPa. O efeito isolado da tensão de água sobre a germinação foi importante apenas quando se considerou os níveis extremos desse fator.

In tropical regions and warm temperature regions, Macrophomina phaseolina is a causal agent of root, stem, and fruit decay in more than 500 cultivated plants species. However, not much is known about the influence of temperature and soil humidity in the germination of microsclerotia. The objective of this study was to evaluate the effect of temperature-water tension interaction in the sand substract on the germination of microsclerotia of the fungus. This work was carried out under laboratory conditions and involved two phases. In the first phase the effect of the interaction of five temperatures with two water tension levels was evaluated. In the second phase, the effect of the interaction of two temperatures with six water tension levels was evaluated. A completely randomized design with factorial arrangement and four replications was used for both experiments. The results showed (P<0.05) that the greatest percents of germination occurred at 30 ºC and 33 ºC. At water a tension of -1,500 kPa microesclerotia germination occurred at all temperatures tested. The water tension of -80 kPa tended to show the highest percent of germination, although it did not differ from -8, -300 and -1,500 kPa water tensions. The microsclerotia did not germinate when sand dried at air temperature; however, they germinated at water tension of 0 kPa, although at a lower rate than the germination at the other water tensions studied. The isolated effects of water tension on the microsclerotia germination were important only when the extremes values of this factor were considered.