ABSTRACT
ABSTRACT Anthracnose is a crop disease usually caused by fungi in the genus Colletotrichum or Gloeosporium. These are considered one of the main pathogens, causing significant economic losses, such as in peppers and guarana. The current forms of control include the use of resistant cultivars, sanitary pruning and fungicides. However, even with the use of some methods of controlling these cultures, the crops are not free of anthracnose. Additionally, excessive application of fungicides increases the resistance of pathogens to agrochemicals and cause harm to human health and the environment. In order to find natural antifungal agents against guarana anthracnose, endophytic fungi were isolated from Amazon guarana. The compounds piliformic acid and cytochalasin D were isolated by chromatographic techniques from two Xylaria spp., guided by assays with Colletotrichum gloeosporioides. The isolated compounds were identified by spectrometric techniques, as NMR and mass spectrometry. This is the first report that piliformic acid and cytochalasin D have antifungal activity against C. gloeosporioides with MIC 2.92 and 2.46 µmol mL-1 respectively. Captan and difenoconazole were included as positive controls (MIC 16.63 and 0.02 µmol mL-1, respectively). Thus, Xylaria species presented a biotechnological potential and production of different active compounds which might be promising against anthracnose disease.
Subject(s)
Plant Diseases/prevention & control , Xylariales/chemistry , Paullinia/microbiology , Endophytes/chemistry , Fungicides, Industrial/pharmacology , Phylogeny , Plant Diseases/microbiology , Mass Spectrometry , Xylariales/isolation & purification , Xylariales/genetics , Xylariales/metabolism , Molecular Structure , Colletotrichum/drug effects , Colletotrichum/physiology , Endophytes/isolation & purification , Endophytes/genetics , Endophytes/metabolism , Fungicides, Industrial/isolation & purification , Fungicides, Industrial/chemistryABSTRACT
RESUMO O objetivo deste trabalho foi avaliar a atividade antifúngica de óleos essenciais e vegetais no controle in vitro de Colletotrichum gloeosporioides, agente causal da antracnose em pós-colheita de frutíferas. Treze óleos essenciais foram utilizados em concentrações de 0,00%, 0,40%, 0,80%, 1,70%, 3,20%, 6,25%, 12,50%, 25,00%, 50,00% e 100,00%, e uma linhagem padrão de Colletotrichum gloeosporioides. Foram avaliadas a concentração inibitória mínima e a concentração mínima fungicida a fim de caracterizar o potencial de cada um dos óleos essenciais avaliados. Verificou-se que os óleos utilizados apresentaram atividade fungicida em diferentes concentrações, as quais variaram de 0,80% (melaleuca), 3,20%, (eucalipto), 6,25% (limão, capim limão, cravo da índia, canela e nim), 12,5% (hortelã e citronela), 25% (copaíba), 50% (coco e gengibre) e 100% (manjericão). O óleo de nim apresentou maior redução da carga microbiana em função do tempo de exposição, sendo necessários 30 minutos para anulação da contagem microbiana. O efeito antifúngico dos óleos essenciais, para controle de Colletotrichum gloeosporioides, depende da planta e da concentração empregada.
ABSTRACT This study aimed to evaluate the antifungal effect of essential and vegetal oils in the in vitro control of Colletotrichum gloeosporioides, a causal agent of anthracnose in fruit postharvest. Thirteen essential oils were used at concentrations of 0.00%, 0.40%, 0.80%, 1.70%, 3.20%, 6.25%, 12.50%, 25.00%, 50.00%, and 100.00%, and also a standard strain of Colletotrichum gloeosporioides, The minimum inhibitory concentration and minimum fungicidal concentration were assessed to characterize the potential of each of the essential oils tested. We found that used oils showed fungicidal activity at different concentrations, which varied in 0.80% (Melaleuca alternifólia), 3.20%, (Eucalyptus globulus), 6.25% (Citrus limonium, Cymbopogon citratus, Syzygium aromaticum, Cinnamomum zeylanicum, and Azadirachta indica), 12.5% (Mentha piperita and Cymbopogon winterianus), 25% (Copaifera langsdorfii), 50% (Cocos nucifera and Zingiber officinale), and 100% (Ocimum basilicum). The Azadirachta indica oil showed greater reduction of microbial load because of the exposure time, and took 30 minutes for annulment of microbial count. The antifungal effect of essential oils to control Colletotrichum gloeosporioides depends on the plant and quantity of concentration.
Subject(s)
Plants/classification , In Vitro Techniques/classification , Oils, Volatile/analysis , Colletotrichum/physiology , Plants, Medicinal/classification , Antifungal Agents/classificationABSTRACT
Con el propósito de desarrollar un protocolo para la formación de microtubérculos en el clon de ñame Pacala Duclos (Dioscorea alata L) en sistema de inmersión temporal, que pudiera ser usado como alternativa para la propagación de esta especie, se deinieron como objetivos de trabajo determinar el efecto del tiempo y la frecuencia de inmersión, así como la inluencia del volumen de medio de cultivo por planta cultivada in vitro. Con el empleo de 15 min de inmersión y una frecuencia de inmersión cada 6 horas, se alcanzaron los mejores resultados en cuanto al número de microtubérculos formados por planta. Con este tiempo y frecuencia de inmersión los microtubérculos presentaron la mayor masa fresca y seca, así como el mayor diámetro. Además, a las 18 semanas de cultivo se obtuvo el mayor número total de microtubérculos por sistema y el mayor número de microtubérculos aprovechables como material vegetal de propagación. En cuanto al volumen de medio de cultivo por planta, con 60 ml de medio de cultivo por planta in vitro se alcanzó el mayor número de microtubérculos aprovechables, los cuales presentaron el contenido más alto de materia seca. Los microtubérculos obtenidos en este tipo de sistema de inmersión temporal presentaron una masa fresca superior a 2,40 gMF, lo cual podría permitir su uso como material de plantación directo a campo
The following working objectives were deined for developing a protocol for ´Pacala Duclos´ yam clone (Dioscorea alata L) microtuber formation in temporary immersion systems (TIS): time effect, immersion frequency and culture medium volume inluence per in vitro cultivated plant. The results led to deining that the highest performance regarding microtuber number formed per plant was achieved with a 15-minute immersion time and six-hourly immersion frequency; the microtubers presented the greatest dry and fresh weight and largest diameter at such immersion time and frequency. Furthermore, the highest total number of microtubers per system and the largest number of microtubers usable for planting (vegetal propagation) material were obtained after 18 weeks culture. Regarding culture medium volume per plant, the greatest amount of usable microtubers was achieved with 60 ml per in vitro plant, microtubers presenting the highest dry matter content. As microtubers obtained in this type of TIS had fresh weights higher than 2.40 gFW they could be used as direct planting material in ield conditions