RESUMO
Plant growth-promoting rhizobacteria (PGPR) are common components of the rhizosphere, but their role in adaptation of plants to extreme environments is not yet understood. Here, we examined rhizobacteria associated with ancient clones of Larrea tridentata in the Mohave desert, including the 11,700-year-old King Clone, which is oldest known specimen of this species. Analysis of unculturable and culturable bacterial community by PCR-DGGE revealed taxa that have previously been described on agricultural plants. These taxa included species of Proteobacteria, Bacteroidetes, and Firmicutes that commonly carry traits associated with plant growth promotion, including genes encoding aminocyclopropane carboxylate deaminase and ß-propeller phytase. The PGPR activities of three representative isolates from L. tridentata were further confirmed using cucumber plants to screen for plant growth promotion. This study provides an intriguing first view of the mutualistic bacteria that are associated with some of the world's oldest living plants and suggests that PGPR likely contribute to the adaptation of L. tridentata and other plant species to harsh environmental conditions in desert habitats.
Assuntos
Bactérias/isolamento & purificação , Clima Desértico , Larrea/crescimento & desenvolvimento , Larrea/microbiologia , Desenvolvimento Vegetal , Rizosfera , Bactérias/classificação , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Bacteroidetes/classificação , Bacteroidetes/genética , Bacteroidetes/crescimento & desenvolvimento , Bacteroidetes/isolamento & purificação , Carbono-Carbono Liases/genética , Carbono-Carbono Liases/metabolismo , Cucumis sativus/crescimento & desenvolvimento , Cucumis sativus/microbiologia , Larrea/genética , Larrea/metabolismo , Dados de Sequência Molecular , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Proteobactérias/classificação , Proteobactérias/genética , Proteobactérias/crescimento & desenvolvimento , Proteobactérias/isolamento & purificação , Análise de Sequência de DNA , Microbiologia do Solo , SimbioseRESUMO
Los ambientes áridos están dominados por vegetación arbustiva, con acumulación de nutrientes bajo la canopia de los arbustos y con suelos relativamente infértiles en los interparches. Los distintos componentes de los vegetales constituyen uno de los hábitat más comunes para las levaduras. Existen numerosos antecedentes acerca de investigaciones sobre levaduras cuyo hábitat lo constituyen árboles y arbustos, sin embargo no existen referencias sobre levaduras asociadas a las Zigofiláceas, una familia de matorrales preponderantes en la Provincia de Monte argentino. El objetivo de este trabajo fue conocer la biodiversidad de levaduras en suelos y canopias asociados con Bulnesia retama y Larrea divaricata, en los Médanos Grandes de Caucete, San Juan, Argentina. Sobre un total de 87 aislamientos de levaduras identificados, se observó una mayor diversidad taxonómica en las asociadas tanto al suelo como a la parte aérea de B. retama, respecto de L. divaricata. A partir de la canopia de B. retama y su suelo asociado se aislaron 9 y 10 especies de levaduras respectivamente, mientras que de la parte aérea y suelo de L. divaricata 4 y 3. Los géneros identificados fueron: Candida, Debaryomyces, Dekkera, Saccharomyces, Torulaspora, Sporidiobolus y Pichia. En total se encontraron 14 especies en todos los microambientes.
Bush like vegetation dominates arid environments, and there is nutrients accumulation under shrub canopies and relatively unfertile soils between vegetal patches areas. Plants are one of the most common habitats for yeasts. There are many reports about yeasts inhabiting different plant components. Nevertheless, there are no reports about yeasts associated with Zigophyllaceae, an important shrub family of the Argentinean Province of Monte. The objective of this work was to analyzed yeast biodiversity of Bulnesia retama and Larrea divaricata canopies and associated soils, at Médanos Grandes of Caucete, San Juan, Argentina. Eighty seven (87) isolated yeasts were identified. From B. retama canopy and associated soil was observed a larger taxonomical diversity respect to L. divaricata. Nine (9) and ten (10) species were isolated from canopy and associated soil of B. retama, respectively. From L. divaricata canopy were 4 species and 3 species from its associated soil isolated. Identified genera were: Candida, Debaryomyces, Dekkera, Saccharomyces, Torulaspora, Sporidiobolus and Pichia. Fourteen (14) species were found at all microenvironments.
Assuntos
Larrea/microbiologia , Microbiologia do Solo , Leveduras/isolamento & purificação , Zygophyllaceae/microbiologia , Argentina , Biodiversidade , Especificidade da EspécieRESUMO
Bush like vegetation dominates arid environments, and there is nutrients accumulation under shrub canopies and relatively unfertile soils between vegetal patches areas. Plants are one of the most common habitats for yeasts. There are many reports about yeasts inhabiting different plant components. Nevertheless, there are no reports about yeasts associated with Zygophyllaceae, an important shrub family of the Argentinean Province of Monte. The objective of this work was to analyzed yeast biodiversity of Bulnesia retama and Larrea divaricata canopies and associated soils, at Medanos Grandes of Caucete, San Juan, Argentina. Eighty seven (87) isolated yeasts were identified. From B. retama canopy and associated soil was observed a larger taxonomical diversity respect to L. divaricata. Nine (9) and ten (10) species were isolated from canopy and associated soil of B. retama, respectively. From L. divaricata canopy were 4 species and 3 species from its associated soil isolated. Identified genera were: Candida, Debaryomyces, Dekkera, Saccharomyces, Torulaspora, Sporidiobolus and Pichia. Fourteen (14) species were found at all microenvironments.