Collaboration between grass seedlings and rhizobacteria to scavenge organic nitrogen in soils.

Plants require nitrogen (N) to make proteins, nucleic acids and other biological molecules. It is widely accepted that plants absorb inorganic forms of N to fill their needs. However, recently it has become clear that plants also have the capacity to absorb organic N from soils.

Endophytic Bacillus spp. produce antifungal lipopeptides and induce host defence gene expression in maize.

Endophytes are mutualistic symbionts within healthy plant tissues. In this study we isolated Bacillus spp. from seeds of several varieties of maize.

Nitrogen acquisition in Agave tequilana from degradation of endophytic bacteria.

Plants form symbiotic associations with endophytic bacteria within tissues of leaves, stems, and roots. It is unclear whether or how plants obtain nitrogen from these endophytic bacteria. Here we present evidence showing nitrogen flow from endophytic bacteria to plants in a process that appears to involve oxidative degradation of bacteria.

Occurrence of Bacillus amyloliquefaciens as a systemic endophyte of vanilla orchids.

We report the occurrence of Bacillus amyloliquefaciens in vanilla orchids (Vanilla phaeantha) and cultivated hybrid vanilla (V. planifolia × V. pompona) as a systemic bacterial endophyte.

Hydrogen peroxide staining to visualize intracellular bacterial infections of seedling root cells.

Visualization of bacteria in living plant cells and tissues is often problematic due to lack of stains that pass through living plant cell membranes and selectively stain bacterial cells. In this article, we report the use of 3,3'-diaminobenzidine tetrachloride (DAB) to stain hydrogen peroxide associated with bacterial invasion of eukaryotic cells. Tissues were counterstained with aniline blue/lactophenol to stain protein in bacterial cells.

A proposed mechanism for nitrogen acquisition by grass seedlings through oxidation of symbiotic bacteria.

In this paper we propose and provide evidence for a mechanism, oxidative nitrogen scavenging (ONS), whereby seedlings of some grass species may extract nitrogen from symbiotic diazotrophic bacteria through oxidation by plant-secreted reactive oxygen species (ROS). Experiments on this proposed mechanism employ tall fescue (Festuca arundinaceae) seedlings to elucidate features of the oxidative mechanism. We employed 15N(2) gas assimilation experiments to demonstrate nitrogen fixation, direct microscopic visualization of bacteria on seedling surfaces to visualize the bacterial oxidation process, reactive oxygen probes to test for the presence of H(2)O(2) and cultural experiments to assess conditions under which H(2)O(2) is secreted by seedlings.

Development of an orthotopic human pancreatic cancer xenograft model using ultrasound guided injection of cells.

Mice have been employed as models of cancer for over a century, providing significant advances in our understanding of this multifaceted family of diseases. In particular, orthotopic tumor xenograft mouse models are emerging as the preference for cancer research due to increased clinical relevance over subcutaneous mouse models. In the current study, we developed orthotopic pancreatic cancer xenograft models in mice by a minimally invasive method, ultrasound guided injection (USGI) comparable to highly invasive surgical orthotopic injection (SOI) methods.

Light converts endosymbiotic fungus to pathogen, influencing seedling survival and niche-space filling of a common tropical tree, Iriartea deltoidea.

Pathogens are hypothesized to play an important role in the maintenance of tropical forest plant species richness. Notably, species richness may be promoted by incomplete filling of niche space due interactions of host populations with their pathogens. A potentially important group of pathogens are endophytic fungi, which asymptomatically colonize plants and are diverse and abundant in tropical ecosystems.

Is plant endophyte-mediated defensive mutualism the result of oxidative stress protection?

In this review, we discuss the biology and beneficial effects of plant endophytes on host plants. The current explanation of endophyte protection (defensive mutualism) of host plants is based on the secondary metabolites (alkaloids) with antiherbivore properties produced by the symbiotic association between host plant and endophytes. We propose an alternative explanation of the mechanism of host protection through enhanced stress tolerance to oxidative stress.

Hypocrella panamensis sp. nov. (Clavicipitaceae, Hypocreales): a new species infecting scale insects on Piper carrilloanum in Panama.

A new species, Hypocrella panamensis, is described from collections and cultures obtained on Barro Colorado Island, Panama. In order to aid in placement of this fungus, phylogenetic analyses were conducted using LSU (rDNA) sequences. Hypocrella panamensis is characterized by possessing pulvinate stromata with a Lecanicillium-like anamorphic state and superficial perithecia.

Endophyte-Mediated Suppression of Dollar Spot Disease in Fine Fescues.

In 1989, a close association was found between single-plant progenies of strong creeping red fescue infected with the endophyte Epichloë festucae and enhanced suppression of dollar spot, a widespread foliar disease of turfgrass caused by Sclerotinia homoeocarpa. From this limited observation, extensive field evaluations were conducted on a wide range of fine fescue germplasm obtained throughout the United States and Europe to determine the frequency and magnitude of this association. In five field trials established between 1985 and 1991, endophyte-infected Chewings, hard, blue, and strong creeping red fescue cultivars, selections, and crosses consistently exhibited endophyte-mediated suppression of dollar spot, when compared with closely related endophyte-free entries.