ABSTRACT
The fungal genus Fonsecaea comprises etiological agents of human chromoblastomycosis, a chronic implantation skin disease. The current hypothesis is that patients acquire the infection through an injury from plant material. The present study aimed to evaluate a model of infection in plant and animal hosts to understand the parameters of trans-kingdom pathogenicity. Clinical strains of causative agents of chromoblastomycosis (Fonsecaea pedrosoi and Fonsecaea monophora) were compared with a strain of Fonsecaea erecta isolated from a living plant. The clinical strains of F. monophora and F. pedrosoi remained concentrated near the epidermis, whereas F. erecta colonized deeper plant tissues, resembling an endophytic behavior. In an invertebrate infection model with larvae of a beetle, Tenebrio molitor, F. erecta exhibited the lowest survival rates. However, F. pedrosoi produced dark, spherical to ovoidal cells that resembled muriform cells, the invasive form of human chromoblastomycosis confirming the role of muriform cells as a pathogenic adaptation in animal tissues. An immunologic assay in BALB/c mice demonstrated the high virulence of saprobic species in animal models was subsequently controlled via host higher immune response.
ABSTRACT
Bactris gasipaes (Arecaceae), also known as peach palm, was domesticated by Amazonian Indians and is cultivated for its fruit and heart-of-palm, a vegetable grown in the tree's inner core. Currently, the conservation of this species relies on in situ conditions and field gene banks. Complementary conservation strategies, such as those based on in vitro techniques, are indicated in such cases. To establish an appropriate cryopreservation protocol, this study aimed to evaluate the ultrastructural features of B. gasipaes embryogenic cultures submitted to vitrification and subsequent cryogenic temperatures. Accordingly, somatic embryo clusters were submitted to Plant Vitrification Solution 3 (PVS3). In general, cells submitted to PVS3 had viable cell characteristics associated with apparently many mitochondria, prominent nucleus, and preserved cell walls. Cells not incubated in PVS3 did not survive after the cryogenic process in liquid nitrogen. The best incubation time for the vitrification technique was 240 min, resulting in a survival rate of 37 %. In these cases, several features were indicative of quite active cell metabolism, including intact nuclei and preserved cell walls, an apparently many of mitochondria and lipid bodies, and the presence of many starch granules and condensed chromatin. Moreover, ultrastructure analysis revealed that overall cellular structures had been preserved after cryogenic treatment, thus validating the use of vitrification in conjunction with cryopreservation of peach palm elite genotypes, as well as wild genotypes, which carry a rich pool of genes that must be conserved.
Subject(s)
Arecaceae/embryology , Arecaceae/cytology , Arecaceae/genetics , Cryopreservation , Seeds/cytology , Seeds/genetics , Survival Analysis , VitrificationABSTRACT
In this work, it was observed a straight relationship between the manipulation of the reduced glutathione (GSH)/glutathione disulfide (GSSG) ratio, nitric oxide emission and quality and number of early somatic embryos in Araucaria angustifolia, a Brazilian endangered native conifer. In low concentrations GSH (0.01 and 0.1mM) is a potential NO scavenger in the culture medium. Furthermore, it can increase the number of early SE formed in cell suspension culture media in a few days. However, the maintenance in this low redox state lead to a loss of early somatic embryos polarization. In gelled culture medium, high levels of GSH (5mM) allows the development of globular embryos presenting a high NO emission on embryo apex, stressing its importance in the differentiation and cell division. Taken together these results indicate that the modification of the embryogenic cultures redox state might be an effective strategy to develop more efficient embryogenic systems in A. angustifolia.
Subject(s)
Glutathione Disulfide/metabolism , Glutathione/metabolism , Nitric Oxide/metabolism , Plant Development , Plant Somatic Embryogenesis Techniques/methods , Seeds/growth & development , Tracheophyta/embryology , Brazil , Cell Division , Endangered Species , Oxidation-Reduction , Seeds/metabolism , Tracheophyta/metabolismABSTRACT
Synthetic seed technologies are useful tools for the field delivery of in vitro derived plantlets. In the present study,different encapsulation procedures and their efficacy in the plantlet regeneration using microshoots of banana cv. Grand Naine were evaluated. Two encapsulation systems were evaluated: i) single encapsulation in beads or droplet hardening method; and ii) double layer or hollow beads. The use of different compounds to enhance the capsule conservation andthe conversion to plantlets was also evaluated. The conversion capacity was assessed in vitro on water-agar culture medium or in ex vitro conditions with Gerbox® boxes. The single encapsulation system showed 80% conversion. The capsules with MS saline formulation treated with 100mM KNO3 showed 76% conversion. Capsules with 1.5g L-1 activated charcoal, and 0.5g L-1 benomyl sucrose-free capsules showed 75% conversion. The encapsulated and non-encapsulatedmicroshoots exhibited 100% germination in response to MS culture medium, and polyethylene glycol after 10 days of storage at 4°C. Sucrose-free capsules showed significantly highergermination (83.3%) than those sucrose-enriched capsules (56.7%). The ex vitro conversion of encapsulated microshoots was 20% in the Gerbox. These results indicate the feasibilityusing synthetic seeds in the large-scale micropropagation of banana cv. Grand Naine.
As tecnologias de semente sintética são ferramentas promissoras para a micropropagação de plantas. O objetivodo presente trabalho foi desenvolver um protocolo de encapsulamento e armazenamento de unidades encapsuláveis a partir de microbrotos de bananeira da cultivar Grand Naine. Foram avaliados dois sistemas de encapsulamento: i) formação de cápsula pelo método de camada simples e ii)camada dupla. Foi avaliada também a adição de diferentes adjuvantes na matriz de alginato para promover a conservação da cápsula e favorecer a conversão em plantas. Para a conversão em planta foram avaliadas as condições in vitro sobre o meio de cultura composto de agar-água e as condiçõesex vitro em caixas Gerbox®. O melhor sistema de encapsulamento para os microbrotos da bananeira da cultivarGrand Naine foi o de camada simples, com 80% de conversão. O emprego da formulação salina MS na forma de endosperma artificial e a descomplexação com 100mM KNO3 favoreceram a conversão de microbrotos (76%). A adição de carvão ativado (1,5g L-1) e de benomyl (0.5g L-1), na ausência de sacarose na matriz de alginato, resultou em 75% de conversão, além de reduzir a oxidação e a contaminação dos microbrotos. Microbrotos encapsulados e não- encapsulados revelaram 100% de germinação em resposta ao meio de cultura MS e PEG após 10 dias de estocagem a 4°C. Cápsulas sem a adiçãode sacarose resultaram em 83,3% de conversão, valor superior ao valor obtido com a adição de sacarose (56,7%). A conversão de microbrotos encapsulados foi de 20% nas condições ex vitro. Os resultados indicam a viabilidade de uso destas tecnologias para a micropropagação em larga escala da cultivar de banana Grand Naine.
