5 research outputs found
Rice and bean AHL-mimic quorum-sensing signals specifically interfere with the capacity to form biofilms by plant-associated bacteria
Many bacteria regulate their gene expression in response to changes in their population density in a process called quorum sensing (QS), which involves communication between cells mediated by small diffusible signal molecules termed autoinducers. n-acyl-homoserine-lactones (AHLs) are the most common autoinducers in proteobacteria. QS-regulated genes are involved in complex interactions between bacteria of the same or different species and even with some eukaryotic organisms. Eukaryotes, including plants, can interfere with bacterial QS systems by synthesizing molecules that interfere with bacterial QS systems.
In this work, the presence of AHL-mimic QS molecules in diverse Oryza sativa (rice) and Phaseolus vulgaris (bean) plant-samples were detected employing three biosensor strains. A more intensive analysis using biosensors carrying the lactonase enzyme showed that bean and rice seed-extract contain molecules that lack the typical lactone ring of AHLs. Interestingly, these molecules specifically alter the QS-regulated biofilm formation of two plant-associated bacteria, Sinorhizobium fredii SMH12 and Pantoea ananatis AMG501, suggesting that plants are able to enhance or to inhibit the bacterial QS systems depending on the bacterial strain. Further studies would contribute to a better understanding of plantâbacteria relationships at the molecular level
Mejorar nuestro propio conocimiento mediante el anĂĄlisis de un episodio de la prĂĄctica: distintos focos de anĂĄlisis
Una de las formas esenciales para lograr una mejor comprensioÌn del contenido del conocimiento del profesor estaÌ ligada al anaÌlisis de su praÌctica. Esa praÌctica puede ser encarada de una forma amplia que no se limite soÌlo a la praÌctica de clase. Por otro lado, una discusioÌn y reflexioÌn sobre una misma situacioÌn de la praÌctica desde diferentes perspectivas teoÌricas y metodoloÌgicas puede contribuir tambieÌn a una mejor comprensioÌn no solo de la praÌctica sino tambieÌn de los instrumentos metodoloÌgicos y teoÌricos en los que se sustenta el anaÌlisis. En esta comunicacioÌn presentamos y discutimos parte del trabajo desarrollado en la reunioÌn intermedia del grupo de investigacioÌn sobre el conocimiento y desarrollo profesional del profesor de la SEIEM y cuyo foco de atencioÌn fue la discusioÌn de las potencialidades del anaÌlisis de un mismo episodio desde cinco focos teoÌricos distintos
Structure and biological activities of lipochitooligosaccharide nodulation signals produced by Bradyrhizobium japonicum USDA 138 under saline and osmotic stress
The establishment of a symbiotic interaction involves a signal exchange between the host legume (flavonoids) and the nitrogen-fixing rhizobia (nodulation factors (NFs)). Likewise, abiotic stress conditions, such as salinity and drought, strongly reduce the nodulation process, possibly affecting also the signal exchange. In this work we characterized the structure and biological activity of NFs produced by Bradyrhizobium japonicum USDA 138 under control, salt, and osmotic stress conditions. This strain is the most widely used in Argentine soybean culture; under control conditions, it produces a mixture of four types of NFs (V(C16:0,MeFuc), V(C18:1,MeFuc), IV(C18:1), and V(C18:1,Ac,MeFuc)). Interestingly, under stress conditions, this strain produces new types of NFs, one common for both stress conditions (V(C16:1,MeFuc)) and another one only present under salt stress (IV(C18:1,MeFuc)). All mixtures of NFs, extracted from control, salt, and osmotic stress conditions, showed biological activity in soybean plants, such as root hair deformation, and the radical application of purified NFs induced systemic differences in dry matter accumulation. The inoculation of soybean with genistein-induced bacteria cultured under both control and stress conditions had a positive effect on the number of nodules formed and in some cases on dry matter accumulation. These responses are not related to changes in chlorophyll fluorescence or greenness index.Instituto de FisiologĂa y Recursos GenĂ©ticos VegetalesFil: Muñoz, Nacira Belen. Instituto Nacional de TecnologĂa Agropecuaria (INTA). Instituto de FisiologĂa y Recursos GenĂ©ticos Vegetales; Argentina. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas FĂsicas y Naturales. CĂĄtedra de FisiologĂa Vegetal; ArgentinaFil: Soria DĂaz, Maria Eugenia. Universidad de Sevilla. Centro de InvestigaciĂłn, TecnologĂa e InnovaciĂłn. Servicio de EspectrometrĂa de Masas; España. Universidad de Sevilla. Departamento de QuĂmica OrgĂĄnica; EspañaFil: Manyani, Hamid. Universidad de Sevilla. Departamento de MicrobiologĂa y ParasitologĂa; EspañaFil: Contreras SĂĄnchez Matamoros, RocĂo. Universidad de Sevilla. Departamento de QuĂmica OrgĂĄnica; EspañaFil: Gil Serrano, Antonio. Universidad de Sevilla. Departamento de QuĂmica OrgĂĄnica; EspañaFil: MegĂas, Manuel. Universidad de Sevilla. Departamento de MicrobiologĂa y ParasitologĂa; EspañaFil: Lascano, Hernan Ramiro. Instituto Nacional de TecnologĂa Agropecuaria (INTA). Instituto de FisiologĂa y Recursos GenĂ©ticos Vegetales; Argentina. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas FĂsicas y Naturales. CĂĄtedra de FisiologĂa Vegetal; Argentin