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Disease Suppressive Soil
Disease suppressive soils function to prevent the establishment of pathogens in the rhizosphere of plants. These soils develop through the establishment of beneficial microbes, known as plant growth-promoting rhizobacteria (PGPR) in the rhizosphere of plant roots. These mutualistic microbes function to increase plant health by fighting against harmful soil microbes either directly or indirectly. As beneficial bacteria occupy space around plant roots they outcompete harmful pathogens by releasing pathogenic suppressive metabolites. PGPR and harmful soil microbes Plant growth promoting rhizobacteria are bacteria that promote plant growth, through fixing nitrogen, producing growth hormones, or even suppressing pathogens. A variety of PGPR genera provide a wide array of functions that directly improve plant health. Bacteria genera '' Rhizobium'' and ''Mesorhizobium'' work to fix nitrogen into a usable form. '' Actinomyces'' and '' Azospirillum'' produce growth hormones that incre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pathogen
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term ''pathogen'' came into use in the 1880s. Typically, the term ''pathogen'' is used to describe an ''infectious'' microorganism or agent, such as a virus, bacterium, protozoan, prion, viroid, or fungus. Small animals, such as helminths and insects, can also cause or transmit disease. However, these animals are usually referred to as parasites rather than pathogens. The scientific study of microscopic organisms, including microscopic pathogenic organisms, is called microbiology, while parasitology refers to the scientific study of parasites and the organisms that host them. There are several pathways through which pathogens can invade a host. The principal pathways have different episodic time frames, but soil has the longest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from the other eukaryotic kingdoms, which by one traditional classification include Plantae, Animalia, Protozoa, and Chromista. A characteristic that places fungi in a different kingdom from plants, bacteria, and some protists is chitin in their cell walls. Fungi, like animals, are heterotrophs; they acquire their food by absorbing dissolved molecules, typically by secreting digestive enzymes into their environment. Fungi do not photosynthesize. Growth is their means of mobility, except for spores (a few of which are flagellated), which may travel through the air or water. Fungi are the principal decomposers in ecological systems. These and other differences place fungi in a single group of related organisms, named the ''Eumycota'' (''t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Solarization
Soil solarization is a non-chemical environmentally friendly method for controlling pests using solar power to increase the soil temperature to levels at which many soil-borne plant pathogens will be killed or greatly weakened. Soil solarization is used in warm climates on a relatively small scale in gardens and organic farms. Soil solarization weakens and kills fungi, bacteria, nematodes, and insect and mite pests along with weeds in the soil by mulching the soil and covering it with a tarp, usually with a transparent polyethylene cover to trap solar energy. This energy causes physical, chemical, and biological changes in the soil community. Soil solarization is dependent upon time, temperature, and soil moisture. It may also be described as methods of decontaminating soil or creating suppressive soils by the use of sunlight. Soil disinfestation Soil solarization is a hydrothermal process of disinfecting the soil of pests, accomplished by solar power (referred to as solar h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crop Rotation
Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. It reduces reliance on one set of nutrients, pest and weed pressure, and the probability of developing resistant pests and weeds. Growing the same crop in the same place for many years in a row, known as monocropping, gradually depletes the soil of certain nutrients and selects for a highly competitive pest and weed community. Without balancing nutrient use and diversifying pest and weed communities, the productivity of monocultures is highly dependent on external inputs. Conversely, a well-designed crop rotation can reduce the need for synthetic fertilizers and herbicides by better using ecosystem services from a diverse set of crops. Additionally, crop rotations can improve soil structure and organic matter, which reduces erosion and increases farm system resilience. History Agriculturalists have long recognized that suitable rotations — such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Exudates
An exudate is a fluid emitted by an organism through pores or a wound, a process known as exuding or exudation. ''Exudate'' is derived from ''exude'' 'to ooze' from Latin ''exsūdāre'' 'to (ooze out) sweat' (''ex-'' 'out' and ''sūdāre'' 'to sweat'). Medicine An exudate is any fluid that filters from the circulatory system into lesions or areas of inflammation. It can be a pus-like or clear fluid. When an injury occurs, leaving skin exposed, it leaks out of the blood vessels and into nearby tissues. The fluid is composed of serum, fibrin, and leukocytes. Exudate may ooze from cuts or from areas of infection or inflammation. Types * Purulent or suppurative exudate consists of plasma with both active and dead neutrophils, fibrinogen, and necrotic parenchymal cells. This kind of exudate is consistent with more severe infections, and is commonly referred to as pus. * Fibrinous exudate is composed mainly of fibrinogen and fibrin. It is characteristic of rheumatic carditis, bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacillus
''Bacillus'' (Latin "stick") is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum ''Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-shaped bacteria; and the plural ''Bacilli'' is the name of the class of bacteria to which this genus belongs. ''Bacillus'' species can be either obligate aerobes which are dependent on oxygen, or facultative anaerobes which can survive in the absence of oxygen. Cultured ''Bacillus'' species test positive for the enzyme catalase if oxygen has been used or is present. ''Bacillus'' can reduce themselves to oval endospores and can remain in this dormant state for years. The endospore of one species from Morocco is reported to have survived being heated to 420 °C. Endospore formation is usually triggered by a lack of nutrients: the bacterium divides within its cell wall, and one side then engulfs the other. They are not true spores (i.e., not an offspring). Endospore formation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudomonas
''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able to colonize a wide range of niches. Their ease of culture ''in vitro'' and availability of an increasing number of ''Pseudomonas'' strain genome sequences has made the genus an excellent focus for scientific research; the best studied species include ''P. aeruginosa'' in its role as an opportunistic human pathogen, the plant pathogen '' P. syringae'', the soil bacterium '' P. putida'', and the plant growth-promoting ''P. fluorescens, P. lini, P. migulae'', and ''P. graminis''. Because of their widespread occurrence in water and plant seeds such as dicots, the pseudomonads were observed early in the history of microbiology. The generic name ''Pseudomonas'' created for these organisms was defined in rather vague terms by Walter Migula i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyphae
A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or more cells surrounded by a tubular cell wall. In most fungi, hyphae are divided into cells by internal cross-walls called "septa" (singular septum). Septa are usually perforated by pores large enough for ribosomes, mitochondria, and sometimes nuclei to flow between cells. The major structural polymer in fungal cell walls is typically chitin, in contrast to plants and oomycetes that have cellulosic cell walls. Some fungi have aseptate hyphae, meaning their hyphae are not partitioned by septa. Hyphae have an average diameter of 4–6 µm. Growth Hyphae grow at their tips. During tip growth, cell walls are extended by the external assembly and polymerization of cell wall components, and the internal production of new cell membrane. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azospirillum
''Azospirillum'' is a Gram-negative, microaerophilic, non- fermentative and nitrogen-fixing bacterial genus from the family of Rhodospirillaceae. ''Azospirillum'' bacteria can promote plant growth. Characteristics The genus ''Azospirillum'' belongs in the alpha-Proteobacteria class of bacteria. ''Azospirillum'' are gram-negative, do not form spores, and have a slightly-twisted oblong-rod shape. ''Azospirillum'' have at least one flagellum and sometimes multiple flagella, which they use to move rapidly. ''Azospirillum'' are aerobic, but many can also function as microaerobic diazotrophs, meaning, under low oxygen conditions, they can change inert nitrogen from the air into biologically useable forms. At least three species, ''A. melinis'', ''A. thiophilum'', and ''A. humicireducens'' are facultative anaerobes, and can live, if necessary, without oxygen. Growth of ''Azospirillum'' is possible between 5 °C and 42 °C and in substrates with a pH of 5 to 9, with optimal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhizosphere
The rhizosphere is the narrow region of soil or substrate that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome. Soil pores in the rhizosphere can contain many bacteria and other microorganisms that feed on sloughed-off plant cells, termed ''rhizodeposition'', and the proteins and sugars released by roots, termed root exudates. This symbiosis leads to more complex interactions, influencing plant growth and competition for resources. Much of the nutrient cycling and disease suppression by antibiotics required by plants, occurs immediately adjacent to roots due to root exudates and metabolic products of symbiotic and pathogenic communities of microorganisms. The rhizosphere also provides space to produce allelochemicals to control neighbours and relatives. The ''rhizoplane'' refers to the root surface including its associated soil particles which closely interact with each other. The plant-soil feedback loop and other p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinomyces
''Actinomyces'' is a genus of the Actinomycetia class of bacteria. They all are gram-positive. ''Actinomyces'' species are facultatively anaerobic and they grow best under anaerobic conditions. ''Actinomyces'' species may form endospores, and while individual bacteria are rod-shaped, ''Actinomyces'' colonies form fungus-like branched networks of hyphae. The aspect of these colonies initially led to the incorrect assumption that the organism was a fungus and to the name ''Actinomyces'', "ray fungus" (from Greek , ray or beam, and , fungus). ''Actinomyces'' species are ubiquitous, occurring in soil and in the microbiota of animals, including the human microbiota. They are known for the important role they play in soil ecology; they produce a number of enzymes that help degrade organic plant material, lignin, and chitin. Thus, their presence is important in the formation of compost. Certain species are commensal in the skin flora, oral flora, gut flora, and vaginal flora of human ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesorhizobium
''Mesorhizobium'' is a genus of Gram-negative soil bacteria. At least one, the nitrogen fixing species, ''Mesorhizobium loti'', forms symbiotic root nodules with plants in the genus '' Lotus''. Strain MAFF303099 of ''M. japonicum'' has been fully sequenced. Species Accepted Species ''Mesorhizobium'' comprises the following species: * '' M. abyssinicae'' Degefu ''et al''. 2013 * '' M. acaciae'' Zhu et al. 2015 * '' M. albiziae'' Wang ''et al''. 2007 * '' M. alhagi'' Chen ''et al''. 2010 * '' M. amorphae'' Wang ''et al''. 1999 * '' M. atlanticum'' Ferraz Helene ''et al''. 2019 * '' M. australicum'' Nandasena ''et al''. 2009 * '' M. calcicola'' De Meyer et al. 2016 * '' M. camelthorni'' Chen ''et al''. 2010 * '' M. cantuariense'' De Meyer et al. 2015 * '' M. caraganae'' Guan ''et al''. 2008 * '' M. carbonis'' Li ''et al''. 2019 * '' M. carmichaelinearum'' De Meyer ''et al''. 2019 * '' M. chacoense'' Velázquez ''et al''. 2001 * '' M. ciceri'' (Nour ''et al''. 1994) Jarvis ''et al'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
