A geyser is a spring characterized by an intermittent discharge of water ejected turbulently and accompanied by steam. As a fairly rare phenomenon, the formation of geysers is due to particular hydrogeological conditions that exist only in a few places on Earth. Generally all geyser field sites are located near active volcanic areas, and the geyser effect is due to the proximity of magma. Generally, surface water works its way down to an average depth of around 2,000 metres (6,600 ft) where it contacts hot rocks. The resultant boiling of the pressurized water results in the geyser effect of hot water and steam spraying out of the geyser's surface vent.
A mycorrhiza is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant's rhizosphere, its root system. Mycorrhizae play important roles in plant nutrition, soil biology, and soil chemistry.
In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist guest (symbiont). The guest is typically provided with nourishment and shelter. Examples include animals playing host to parasitic worms, cells harbouring pathogenic (disease-causing) viruses, a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria. More specifically in botany, a host plant supplies food resources to micropredators, which have an evolutionarily stable relationship with their hosts similar to ectoparasitism. The host range is the collection of hosts that an organism can use as a partner.
An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; however, most of the endophyte/plant relationships are not well understood. Some endophytes may enhance host growth, nutrient acquisition and improve the plant's ability to tolerate abiotic stresses, such as drought and decrease biotic stresses by enhancing plant resistance to insects, pathogens and herbivores.
Dichanthelium is genus of flowering plants of the grass family, Poaceae. They are known commonly as rosette grasses and panicgrasses.
Frankia is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants, similar to the Rhizobium bacteria found in the root nodules of legumes in the family Fabaceae. Frankia also initiate the forming of root nodules.
Festuca ovina, sheep's fescue or sheep fescue, is a species of grass. It is sometimes confused with hard fescue.
Curvularia is a genus of hyphomycete (mold) fungi which can be pathogens but also act as beneficial partners of many plant species. They are common in soil. Most Curvularia species are found in tropical regions, though a few are found in temperate zones.
Mycoviruses, also known as mycophages, are viruses that infect fungi. The majority of mycoviruses have double-stranded RNA (dsRNA) genomes and isometric particles, but approximately 30% have positive-sense, single-stranded RNA (+ssRNA) genomes.
Epichloë is a genus of ascomycete fungi forming an endophytic symbiosis with grasses. Grass choke disease is a symptom in grasses induced by some Epichloë species, which form spore-bearing mats (stromata) on tillers and suppress the development of their host plant's inflorescence. For most of their life cycle however, Epichloë grow in the intercellular space of stems, leaves, inflorescences, and seeds of the grass plant without incurring symptoms of disease. In fact, they provide several benefits to their host, including the production of different herbivore-deterring alkaloids, increased stress resistance, and growth promotion.
Puccinia coronata is a plant pathogen and causal agent of oat and barley crown rust. The pathogen occurs worldwide, infecting both wild and cultivated oats. Crown rust poses a threat to barley production, because the first infections in barley occur early in the season from local inoculum. Crown rusts have evolved many different physiological races within different species in response to host resistance. Each pathogenic race can attack a specific line of plants within the species typical host. For example, there are over 290 races of P. coronata. Crops with resistant phenotypes are often released, but within a few years virulent races have arisen and P. coronata can infect them.
Festuca arundinacea (syn., Schedonorus arundinaceus and Lolium arundinaceum) is a species of grass commonly known as tall fescue. It is a cool-season perennial C3 species of bunchgrass native to Europe. It is an important forage grass throughout Europe, and many cultivars have been used in agriculture. It is also an ornamental grass in gardens, and a phytoremediation plant.
Curvularia protuberata is a species of fungus in the family Pleosporaceae. It forms a mutualistic relationship with Dichanthelium lanuginosum and Curvularia thermal tolerance virus that allows the grass to grow in soils that are far warmer than it normally tolerates. The mutualism allows the grass to thrive in soil that is 65 °C in Yellowstone National Park. Experiments have shown that the plant can only survive when it is infected by C. protuberata and when C. protuberata is also infected with the virus. This is an example of a tritrophic interaction, as three organisms are interacting.
Serendipita indica is a fungal species of the order Sebacinales. It is an endophytic root-colonising species, discovered from orchid plants in the Thar desert in Rajasthan, India by Prof. Ajit Verma and group, School of Life Sciences, Jawaharlal Nehru University, New Delhi. The fungus has typical pear-shaped chlamydospores. S. indica can be easily grown on various substrates. It has been found to promote plant growth during its mutualistic symbiotic relationship with a wide variety of plants. Experiments have shown that S. indica increases the resistance of colonized plants against fungal pathogens. It has also been found in experiments with barley that S. indica-inoculated plants are tolerant to salt stress and more resistant to root pathogens. S. indica-infested roots also show antioxidant capacity. The fungus also induces systemic disease resistance in plants. S. indica was found to require host cell death for proliferation during mutualistic symbiosis in barley. Its genome has been sequenced and was published in 2011.
Soil microbiology is the study of microorganisms in soil, their functions, and how they affect soil properties. It is believed that between two and four billion years ago, the first ancient bacteria and microorganisms came about on Earth's oceans. These bacteria could fix nitrogen, in time multiplied, and as a result released oxygen into the atmosphere. This led to more advanced microorganisms, which are important because they affect soil structure and fertility. Soil microorganisms can be classified as bacteria, actinomycetes, fungi, algae and protozoa. Each of these groups has characteristics that define them and their functions in soil.
Grapevine virus A (GVA) is a moderately common genetic virus that affects Vitis vinifera and American Vitis grapevine species throughout the world and can be fatal if not treated. Grapevine virus A is in the family Betaflexiviridae and genus Vitivirus. The common name for this virus is grapevine closterovirus. Common symptoms in infected grapevines include stem pitting. Although there is a treatment available to cure infected grapevines, it is not one hundred percent effective, so preventative measures are the best solution to the virus. Every inhabited continent on the globe has had breakouts of grapevine closterovirus due to the complex genetic makeup of the virus. Grapevine virus A has a single-stranded RNA genome, which is similar to that of Grapevine virus B. There are multiple strains of the virus that vary both molecularly and biologically which account for the slightly different symptoms exhibited by infected plants.
Cecil Edmund Yarwood (1908–1981) was an American-Canadian plant pathologist whose work focused on obligate parasites of plants, viruses, and conditions that predisposed plants to infections. He is considered an authority on rust (fungus) and powdery mildew.
Thermophyte is an organism which is tolerant or thriving at high temperatures. These organisms are categorized according to ecological valences at high temperatures, including biological extremely. Such organisms included the hot-spring taxa also.
Dichanthelium lindheimeri, commonly called Lindheimer panicgrass, is a species of flowering plant in the grass family (Poaceae). It is native primarily to eastern areas the United States and Canada, with its range extending into the South Central region. There are also outlying western populations in California, New Mexico and Oregon.
