Mycorrhizae. Medical search

Mycorrhizae: Symbiotic combination (dual organism) of the MYCELIUM of FUNGI with the roots of plants (PLANT ROOTS). The roots of almost all higher plants exhibit this mutually beneficial relationship, whereby the fungus supplies water and mineral salts to the plant, and the plant supplies CARBOHYDRATES to the fungus. There are two major types of mycorrhizae: ectomycorrhizae and endomycorrhizae.Glomeromycota: A phylum of fungi that are mutualistic symbionts and form ARBUSCULAR MYCORRHIZAE with PLANT ROOTS.Symbiosis: The relationship between two different species of organisms that are interdependent; each gains benefits from the other or a relationship between different species where both of the organisms in question benefit from the presence of the other.Plant Roots: The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)Corylus: A plant genus of the family BETULACEAE known for the edible nuts.Ericaceae: The heath plant family of the order Ericales, subclass Dilleniidae, class Magnoliopsida that are generally shrubs or small trees. Leaves are alternate, simple, and leathery; flowers are symmetrical with a 4- or 5-parted corolla of partly fused petals.Lotus: A plant genus of the family FABACEAE. This genus was formerly known as Tetragonolobus. The common name of lotus is also used for NYMPHAEA and NELUMBO.Daucus carota: A plant species of the family APIACEAE that is widely cultivated for the edible yellow-orange root. The plant has finely divided leaves and flat clusters of small white flowers.Fungi: A kingdom of eukaryotic, heterotrophic organisms that live parasitically as saprobes, including MUSHROOMS; YEASTS; smuts, molds, etc. They reproduce either sexually or asexually, and have life cycles that range from simple to complex. Filamentous fungi, commonly known as molds, refer to those that grow as multicellular colonies.Polygonum: A plant genus of the family POLYGONACEAE that is an ingredient of Shou-Wu-Pian, a Chinese herbal preparation (DRUGS, CHINESE HERBAL). The common name of black bindweed also refers to TAMUS or Fallopia (use POLYGONACEAE).Basidiomycota: A phylum of fungi that produce their sexual spores (basidiospores) on the outside of the basidium. It includes forms commonly known as mushrooms, boletes, puffballs, earthstars, stinkhorns, bird's-nest fungi, jelly fungi, bracket or shelf fungi, and rust and smut fungi.Amanita: A genus of fungi of the family Agaricaceae, order Agaricales; most species are poisonous.Frankia: Genus of BACTERIA in the family Frankiaceae. They are nitrogen-fixing root-nodule symbionts of many species of woody dicotyledonous plants.Pseudotsuga: A plant genus in the family PINACEAE, order Pinales, class Pinopsida, division Coniferophyta. They are coniferous evergreen trees with long, flat, spirally arranged needles that grow directly from the branch.Pinus sylvestris: A plant species of the genus PINUS which is the source of pinosylvin. It is sometimes called Scotch pine or Scots pine, which is also a common name for other species of this genus.Medicago: A plant genus of the family FABACEAE. It is distinct from Sweet Clover (MELILOTUS), from Bush Clover (LESPEDEZA), and from Red Clover (TRIFOLIUM).Mycelium: The body of a fungus which is made up of HYPHAE.Medicago truncatula: A plant species of the family FABACEAE used to study GENETICS because it is DIPLOID, self fertile, has a small genome, and short generation time.Biomass: Total mass of all the organisms of a given type and/or in a given area. (From Concise Dictionary of Biology, 1990) It includes the yield of vegetative mass produced from any given crop.Soil: The unconsolidated mineral or organic matter on the surface of the earth that serves as a natural medium for the growth of land plants.Orchidaceae: A plant family of the order Orchidales, subclass Liliidae, class Liliopsida (monocotyledons). All orchids have the same bilaterally symmetrical flower structure, with three sepals, but the flowers vary greatly in color and shape.Agaricales: An extensive order of basidiomycetous fungi whose fruiting bodies are commonly called mushrooms.Soil Microbiology: The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms.Root Nodules, Plant: Knobbed structures formed from and attached to plant roots, especially of LEGUMES, which result from symbiotic infection by nitrogen fixing bacteria such as RHIZOBIUM or FRANKIA. Root nodules are structures related to MYCORRHIZAE formed by symbiotic associations with fungi.Trees: Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.Plant Shoots: New immature growth of a plant including stem, leaves, tips of branches, and SEEDLINGS.Phosphorus: A non-metal element that has the atomic symbol P, atomic number 15, and atomic weight 31. It is an essential element that takes part in a broad variety of biochemical reactions.Carbon: A nonmetallic element with atomic symbol C, atomic number 6, and atomic weight [12.0096; 12.0116]. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE; and as SOOT from incompletely burned fuel.Ascomycota: A phylum of fungi which have cross-walls or septa in the mycelium. The perfect state is characterized by the formation of a saclike cell (ascus) containing ascospores. Most pathogenic fungi with a known perfect state belong to this phylum.Nitrogen: An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.Spores, Fungal: Reproductive bodies produced by fungi.Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Seedling: Very young plant after GERMINATION of SEEDS.DNA, Ribosomal Spacer: The intergenic DNA segments that are between the ribosomal RNA genes (internal transcribed spacers) and between the tandemly repeated units of rDNA (external transcribed spacers and nontranscribed spacers).Lycopersicon esculentum: A plant species of the family SOLANACEAE, native of South America, widely cultivated for their edible, fleshy, usually red fruit.Gene Expression Regulation, Plant: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in plants.Genes, Plant: The functional hereditary units of PLANTS.Plants: Multicellular, eukaryotic life forms of kingdom Plantae (sensu lato), comprising the VIRIDIPLANTAE; RHODOPHYTA; and GLAUCOPHYTA; all of which acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations.DNA, Fungal: Deoxyribonucleic acid that makes up the genetic material of fungi.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Hydroponics: A technique for growing plants in culture solutions rather than in soil. The roots are immersed in an aerated solution containing the correct proportions of essential mineral salts. (From Concise Dictionary of Biology, 1990)Lactobacillus reuteri: A species of gram-positive, rod-shaped LACTIC ACID bacteria found naturally in the human intestinal flora and BREAST MILK.Trichoderma: A mitosporic fungal genus frequently found in soil and on wood. It is sometimes used for controlling pathogenic fungi. Its teleomorph is HYPOCREA.Bacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.Probiotics: Live microbial DIETARY SUPPLEMENTS which beneficially affect the host animal by improving its intestinal microbial balance. Antibiotics and other related compounds are not included in this definition. In humans, lactobacilli are commonly used as probiotics, either as single species or in mixed culture with other bacteria. Other genera that have been used are bifidobacteria and streptococci. (J. Nutr. 1995;125:1401-12)Metals, Heavy: Metals with high specific gravity, typically larger than 5. They have complex spectra, form colored salts and double salts, have a low electrode potential, are mainly amphoteric, yield weak bases and weak acids, and are oxidizing or reducing agents (From Grant & Hackh's Chemical Dictionary, 5th ed)BooksTalus: The second largest of the TARSAL BONES. It articulates with the TIBIA and FIBULA to form the ANKLE JOINT.Environmental Pollution: Contamination of the air, bodies of water, or land with substances that are harmful to human health and the environment.Environmental Monitoring: The monitoring of the level of toxins, chemical pollutants, microbial contaminants, or other harmful substances in the environment (soil, air, and water), workplace, or in the bodies of people and animals present in that environment.Air Pollution: The presence of contaminants or pollutant substances in the air (AIR POLLUTANTS) that interfere with human health or welfare, or produce other harmful environmental effects. The substances may include GASES; PARTICULATE MATTER; or volatile ORGANIC CHEMICALS.

The arbuscular mycorrhizal symbiosis: a molecular review of the fungal dimension. (1/560)

Mycorrhizal associations vary widely in structure and function, but the most common interaction is the arbuscular mycorrhizal (AM) symbiosis. This interaction is formed between the roots of over 80% of all terrestrial plant species and Zygomycete fungi from the Order Glomales. These fungi are termed AM fungi and are obligate symbionts which form endomycorrhizal symbioses. This symbiosis confers benefits directly to the host plant's growth and development through the acquisition of P and other mineral nutrients from the soil by the fungus. In addition, they may also enhance the plant's resistance to biotic and abiotic stresses. These beneficial effects of the AM symbiosis occur as a result of a complex molecular dialogue between the two symbiotic partners. Identifying the molecules involved in the dialogue is a prerequisite for a greater understanding of the symbiosis. Ongoing research attempts to understand the underlying dialogue and concomitant molecular changes occurring in the plant and the fungus during the establishment of a functioning AM symbiosis. This paper focuses on the molecular approaches being used to study AM fungal genes being expressed in the symbiotic and asymbiotic stages of its lifecycle. In addition, the importance of studying these fungi, in relation to understanding plant processes, is discussed briefly. (+info)

Legume genomes and discoveries in symbiosis research. (2/560)

A report on the First International Conference on Legume Genomics and Genetics: Translation to Crop Improvement, Minneapolis-St. Paul, USA, 2-6 June 2002. (+info)

The indolic compound hypaphorine produced by ectomycorrhizal fungus interferes with auxin action and evokes early responses in nonhost Arabidopsis thaliana. (3/560)

Signals leading to mycorrhizal differentiation are largely unknown. We have studied the sensitivity of the root system from plant model Arabidopsis thaliana to hypaphorine, the major indolic compound isolated from the basidiomycetous fungus Pisolithus tinctorius. This fungi establishes ectomycorrhizas with Eucalyptus globulus. Hypaphorine controls root hair elongation and counteracts the activity of indole-3-acetic acid on root elongation on A. thaliana, as previously reported for the host plant. In addition, we show that hypaphorine counteracts the rapid upregulation by indole-3-acetic acid and 1-naphthalenic-acetic acid of the primary auxin-responsive gene IAA1 and induces a rapid, transient membrane depolarization in root hairs and suspension cells, due to the modulation of anion and K+ currents. These early responses indicate that components necessary for symbiosis-related differentiation events are present in the nonhost plant A. thaliana and provide tools for the dissection of the hypaphorine-auxin interaction. (+info)

A phosphate transporter from Medicago truncatula involved in the acquisition of phosphate released by arbuscular mycorrhizal fungi. (4/560)

Many plants have the capacity to obtain phosphate via a symbiotic association with arbuscular mycorrhizal (AM) fungi. In AM associations, the fungi release phosphate from differentiated hyphae called arbuscules, that develop within the cortical cells, and the plant transports the phosphate across a symbiotic membrane, called the periarbuscular membrane, into the cortical cell. In Medicago truncatula, a model legume used widely for studies of root symbioses, it is apparent that the phosphate transporters known to operate at the root-soil interface do not participate in symbiotic phosphate transport. EST database searches with short sequence motifs shared by known phosphate transporters enabled the identification of a novel phosphate transporter from M. truncatula, MtPT4. MtPT4 is significantly different from the plant root phosphate transporters cloned to date. Complementation of yeast phosphate transport mutants indicated that MtPT4 functions as a phosphate transporter, and estimates of the K(m) suggest a relatively low affinity for phosphate. MtPT4 is expressed only in mycorrhizal roots, and the MtPT4 promoter directs expression exclusively in cells containing arbuscules. MtPT4 is located in the membrane fraction of mycorrhizal roots, and immunolocalization revealed that MtPT4 colocalizes with the arbuscules, consistent with a location on the periarbuscular membrane. The transport properties and spatial expression patterns of MtPT4 are consistent with a role in the acquisition of phosphate released by the fungus in the AM symbiosis. (+info)

Genetic and cytogenetic mapping of DMI1, DMI2, and DMI3 genes of Medicago truncatula involved in Nod factor transduction, nodulation, and mycorrhization. (5/560)

The DMI1, DMI2, and DMI3 genes of Medicago truncatula, which are required for both nodulation and mycorrhization, control early steps of Nod factor signal transduction. Here, we have used diverse approaches to pave the way for the map-based cloning of these genes. Molecular amplification fragment length polymorphism markers linked to the three genes were identified by bulked segregant analysis. Integration of these markers into the general genetic map of M. truncatula revealed that DMI1, DMI2, and DMI3 are located on linkage groups 2, 5, and 8, respectively. Cytogenetic studies using fluorescent in situ hybridization (FISH) on mitotic and pachytene chromosomes confirmed the location of DMI1, DMI2, and DMI3 on chromosomes 2, 5, and 8. FISH-pachytene studies revealed that the three genes are in euchromatic regions of the genome, with a ratio of genetic to cytogenetic distances between 0.8 and 1.6 cM per microm in the DMI1, DMI2, and DMI3 regions. Through grafting experiments, we showed that the genetic control of the dmi1, dmi2, and dmi3 nodulation phenotypes is determined at the root level. This means that mutants can be transformed by Agrobacterium rhizogenes to accelerate the complementation step of map-based cloning projects for DMI1, DMI2, and DMI3. (+info)

Phosphorus effects on metabolic processes in monoxenic arbuscular mycorrhiza cultures. (6/560)

The influence of external phosphorus (P) on carbon (C) allocation and metabolism as well as processes related to P metabolism was studied in monoxenic arbuscular mycorrhiza cultures of carrot (Daucus carota). Fungal hyphae of Glomus intraradices proliferated from the solid minimal medium containing the colonized roots into C-free liquid minimal medium with different P treatments. The fungus formed around three times higher biomass in P-free liquid medium than in medium with 2.5 mM inorganic P (high-P). Mycelium in the second experiment was harvested at an earlier growth stage to study metabolic processes when the mycelium was actively growing. P treatment influenced the root P content and [(13)C]glucose administered to the roots 7 d before harvest gave a negative correlation between root P content and (13)C enrichment in arbuscular mycorrhiza fungal storage lipids in the extraradical hyphae. Eighteen percent of the enriched (13)C in extraradical hyphae was recovered in the fatty acid 16:1omega5 from neutral lipids. Polyphosphate accumulated in hyphae even in P-free medium. No influence of P treatment on fungal acid phosphatase activity was observed, whereas the proportion of alkaline-phosphatase-active hyphae was highest in high-P medium. We demonstrated the presence of a motile tubular vacuolar system in G. intraradices. This system was rarely seen in hyphae subjected to the highest P treatment. We concluded that the direct responses of the extraradical hyphae to the P concentration in the medium are limited. The effects found in hyphae seemed instead to be related to increased availability of P to the host root. (+info)

Induction of jasmonate biosynthesis in arbuscular mycorrhizal barley roots. (7/560)

Colonization of barley (Hordeum vulgare cv Salome) roots by an arbuscular mycorrhizal fungus, Glomus intraradices Schenck & Smith, leads to elevated levels of endogenous jasmonic acid (JA) and its amino acid conjugate JA-isoleucine, whereas the level of the JA precursor, oxophytodienoic acid, remains constant. The rise in jasmonates is accompanied by the expression of genes coding for an enzyme of JA biosynthesis (allene oxide synthase) and of a jasmonate-induced protein (JIP23). In situ hybridization and immunocytochemical analysis revealed that expression of these genes occurred cell specifically within arbuscule-containing root cortex cells. The concomitant gene expression indicates that jasmonates are generated and act within arbuscule-containing cells. By use of a near-synchronous mycorrhization, analysis of temporal expression patterns showed the occurrence of transcript accumulation 4 to 6 d after the appearance of the first arbuscules. This suggests that the endogenous rise in jasmonates might be related to the fully established symbiosis rather than to the recognition of interacting partners or to the onset of interaction. Because the plant supplies the fungus with carbohydrates, a model is proposed in which the induction of JA biosynthesis in colonized roots is linked to the stronger sink function of mycorrhizal roots compared with nonmycorrhizal roots. (+info)

Exploring root symbiotic programs in the model legume Medicago truncatula using EST analysis. (8/560)

We report on a large-scale expressed sequence tag (EST) sequencing and analysis program aimed at characterizing the sets of genes expressed in roots of the model legume Medicago truncatula during interactions with either of two microsymbionts, the nitrogen-fixing bacterium Sinorhizobium meliloti or the arbuscular mycorrhizal fungus Glomus intraradices. We have designed specific tools for in silico analysis of EST data, in relation to chimeric cDNA detection, EST clustering, encoded protein prediction, and detection of differential expression. Our 21 473 5'- and 3'-ESTs could be grouped into 6359 EST clusters, corresponding to distinct virtual genes, along with 52 498 other M.truncatula ESTs available in the dbEST (NCBI) database that were recruited in the process. These clusters were manually annotated, using a specifically developed annotation interface. Analysis of EST cluster distribution in various M.truncatula cDNA libraries, supported by a refined R test to evaluate statistical significance and by 'electronic northern' representation, enabled us to identify a large number of novel genes predicted to be up- or down-regulated during either symbiotic root interaction. These in silico analyses provide a first global view of the genetic programs for root symbioses in M.truncatula. A searchable database has been built and can be accessed through a public interface. (+info)