Allorhizobium vitis | |
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Species: | A. vitis |
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Allorhizobium vitis | |
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Allorhizobium vitis is a plant pathogen that infects grapevines. The species is best known for causing a tumor known as crown gall disease. [5] One of the virulent strains, A. vitis S4, is responsible both for crown gall on grapevines and for inducing a hypersensitive response in other plant species. [6] Grapevines that have been affected by crown gall disease produce fewer grapes than unaffected plants. [7] Though not all strains of A. vitis are tumorigenic, most strains can damage plant hosts. [6] [8]
A. vitis shares many genetic and morphological characteristics with several Agrobacterium species, including A. tumefaciens. [9] The two species have overlapping host ranges, and both A. vitis and A. tumefaciens may reduce the yield of infected crops. [9] For this reason, research on A. vitis focuses on transmission and methods of control.
A. vitis is a Gram-negative bacterium with a thin peptidoglycan layer in its cell wall. [10] The species is aerobic and mesophilic, with individual cells that are rod-shaped and motile. [10] On culture, colonies are round, white, and translucent. [9]
The presence of A. vitis has been confirmed in Germany, France, Austria, Hungary, South Africa, and the United States. [6] Crown gall disease outbreaks in Europe and North America in the mid-1980s have been linked to A. vitis, and the species has continued to survive in those regions. [6] Additionally, a survey conducted in China from 2003 to 2009 identified strains of A. vitis on blighted banana plants. [11]
The genome of A. vitis consists of two circular chromosomes and five plasmids. [8] It is 6.32 Mb long and encodes 5549 proteins. [10] Four rRNA operons have been identified. [6] [8] Tumorigenic strains contain a Ti plasmid (pTi). [9] Ti plasmids in galls produce various opines that are then secreted from the gall. [6] In a vitis, pTi codes for octopine and/or cucumopine. [12] Tumorigenic strains also contain a plasmid that allows the bacterium to utilize tartrate. [9]
A. vitis was formerly referred to as Agrobacterium biovar III. [8] Originally, the species included only biovar III strains found in grape hosts. [6] Since then, A. vitis has been redefined to include all biovar III strains. [11] It can be distinguished from biovars I and II, A. tumefaciens and A. rhizogenes , on the basis of its hosts and pathogenicity. [8] Fatty acid analysis also reveals differences between A. vitis and other strains of tumorigenic bacteria. [6]
A. vitis has also been classified in the genus Rhizobium . [4] A 1999 study suggested that A. vitis is more closely related to Rhizobium galegae than to other Agrobacterium species, based on genetic sequence comparison. [6] In 2001, Young et al. proposed that A. vitis be reclassified as Rhizobium vitis. [4] More recently, A. vitis was transferred to the genus Allorhizobium . [1] [2]
Grapevines are the plants most commonly infected with A. vitis. [6] Though A. vitis may cause hypersensitive response in other plant species, crown gall disease induced by tumorigenic A. vitis is unique to grapevines. [8] All strains of A. vitis induce grape root necrosis. [9] Because A. vitis may remain latent, not all infected plants show symptoms. [9]
An intraspecific taxon of A. vitis has been isolated from banana leaves in China. [11] A. vitis may also infect tomato plants, and has been shown to cause leaf panel collapse in tobacco. [12]
The Ti plasmid is responsible for transmission of crown gall disease in plants infected with A. vitis. [9] Tumorigenic A. vitis transfers its Ti plasmid to other bacteria, and transfers T-DNA into plants. [6] Virulence genes encoded by the Ti plasmid generate single-strand T-DNA molecules, which in turn are transferred to healthy hosts. [5] Disorganized cell division occurs in infected hosts, leading to gall development instead of the formation of healthy vascular tissue. [9]
Propagation of diseased wood often transmits A. vitis. [7] Injuries to a grapevine caused by cutting or freezing may also make the plant more susceptible to crown gall infection. [6] However, galls grow only on trunks or canes, and do not appear on the roots of infected plants. [9]
When A. vitis causes crown gall disease, several symptoms and tests can be used to identify its presence. On grapevines, young galls appear as soft green bumps, which later become brown and rough. [7] Galls do not appear on all grapevines in which A. vitis is present. [7]
Steps can be taken to control crown gall disease and reduce the risk of infection. Injured sites on vines, such as those caused by freezing or cutting injuries, are especially susceptible to infection. [6] Planting in frost-prone areas or areas with poor drainage should therefore be avoided. [7] Reducing other grapevine stressors, such as nutrient deprivation and low soil pH, also limits susceptibility. [7] Additionally, some cultivars are resistant to crown gall disease. Vitis vinifera is generally susceptible to crown gall disease, but resistant grape species can be planted preferentially. [7]
Grape necrosis is a common symptom of A. vitis infection, caused by both tumorigenic and non-tumorigenic bacteria strains. [9] Tobacco leaf panel collapse can be induced by the non-tumorigenic F2/5 strain of A. vitis. [13] While the strain of A. vitis found in grapevines, A. vitis pv. vitis, is responsible for most diseases, banana leaf blights have been linked to A. vitis pv. musae. [11]
Strains of bacteria can be used as biological control agents to limit the growth of pathogenic A. vitis. Grapevine roots that have been soaked in a suspension containing the inhibitory strain are less susceptible than those that have not. [9] [12] Several ACC deaminase-producing species found in the rhizosphere inhibit A. vitis tumor production in tomato plants. [12] Non-tumorigenic strains of A. vitis (F2/5, ARK-1, and VAR03-1) have been shown to limit crown gall formation. [9] [14] [15] In investigations involving these strains, F2/5 still induced necrosis but ARK-1 did not. [13] [14]
Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. This takes place through a pilus. It is a parasexual mode of reproduction in bacteria.
Rhizobium is a genus of Gram-negative soil bacteria that fix nitrogen. Rhizobium species form an endosymbiotic nitrogen-fixing association with roots of legumes and Parasponia.
Agrobacterium tumefaciens is the causal agent of crown gall disease in over 140 species of eudicots. It is a rod-shaped, Gram-negative soil bacterium. Symptoms are caused by the insertion of a small segment of DNA, from a plasmid into the plant cell, which is incorporated at a semi-random location into the plant genome. Plant genomes can be engineered by use of Agrobacterium for the delivery of sequences hosted in T-DNA binary vectors.
Agrobacterium is a genus of Gram-negative bacteria established by H. J. Conn that uses horizontal gene transfer to cause tumors in plants. Agrobacterium tumefaciens is the most commonly studied species in this genus. Agrobacterium is well known for its ability to transfer DNA between itself and plants, and for this reason it has become an important tool for genetic engineering.
The transfer DNA is the transferred DNA of the tumor-inducing (Ti) plasmid of some species of bacteria such as Agrobacterium tumefaciens and Agrobacterium rhizogenes(actually an Ri plasmid). The T-DNA is transferred from bacterium into the host plant's nuclear DNA genome. The capability of this specialized tumor-inducing (Ti) plasmid is attributed to two essential regions required for DNA transfer to the host cell. The T-DNA is bordered by 25-base-pair repeats on each end. Transfer is initiated at the right border and terminated at the left border and requires the vir genes of the Ti plasmid.
The Rhizobiaceae is a family of proteobacteria comprising multiple subgroups that enhance and hinder plant development. Some bacteria found in the family are used for plant nutrition and collectively make up the rhizobia. Other bacteria such as Agrobacterium tumefaciens and A. rhizogenes severely alter the development of plants in their ability to induce crown galls or hairy roots found on the stem. The family has been of an interest to scientists for centuries in their ability to associate with plants and modify plant development. The Rhizobiaceae are, like all Proteobacteria, Gram-negative. They are aerobic, and the cells are usually rod-shaped. Many species of the Rhizobiaceae are diazotrophs which are able to fix nitrogen and are symbiotic with plant roots.
A tumour inducing (Ti) plasmid is a plasmid found in pathogenic species of Agrobacterium, including A. tumefaciens, A. rhizogenes, A. rubi and A. vitis.
Rhizobium rhizogenes is a Gram-negative soil bacterium that produces hairy root disease in dicotyledonous plants. R. rhizogenes induces the formation of proliferative multiple-branched adventitious roots at the site of infection, so-called 'hairy roots'.
Alphaproteobacteria is a class of bacteria in the phylum Proteobacteria. Its members are highly diverse and possess few commonalities, but nevertheless share a common ancestor. Like all Proteobacteria, its members are gram-negative and some of its intracellular parasitic members lack peptidoglycan and are consequently gram variable.
Opines are low molecular weight compounds found in plant crown gall tumors or hairy root tumors produced by pathogenic bacteria of the genus Agrobacterium and Rhizobium. Opine biosynthesis is catalyzed by specific enzymes encoded by genes contained in a small segment of DNA, which is part of the Ti plasmid or Ri plasmid, inserted by the bacterium into the plant genome. The opines are used by the bacterium as an important energy, carbon and nitrogen source. Each strain of Agrobacterium and Rhizobium induces and catabolizes a specific set of opines, this set typifying the Ti plasmid and Ri plasmid. There are some 30 different opines described so far.
Rhodococcus fascians is a Gram positive bacterial phytopathogen that causes leafy gall disease. R. fascians is the only phytopathogenic member of the genus Rhodococcus; its host range includes both dicotyledonous and monocotyledonous hosts. Because it commonly afflicts tobacco (Nicotiana) plants, it is an agriculturally significant pathogen.
Pseudomonas savastanoi is a gram-negative plant pathogenic bacterium that infects a variety of plants. It was once considered a pathovar of Pseudomonas syringae, but following DNA-relatedness studies, it was instated as a new species. It is named after Savastano, a worker who proved between 1887 and 1898 that olive knot are caused by bacteria.
Plant transformation vectors are plasmids that have been specifically designed to facilitate the generation of transgenic plants. The most commonly used plant transformation vectors are termed binary vectors because of their ability to replicate in both E. coli, a common lab bacterium, and Agrobacterium tumefaciens, a bacterium used to insert the recombinant (customized) DNA into plants. Plant Transformation vectors contain three key elements;
A transfer DNA (T-DNA) binary system is a pair of plasmids consisting of a T-DNA binary vector and a virhelper plasmid. The two plasmids are used together to produce genetically modified plants. They are artificial vectors that have been derived from the naturally occurring Ti plasmid found in bacterial species of the genus Agrobacterium, such as A. tumefaciens. The binary vector is a shuttle vector, so-called because it is able to replicate in multiple hosts.
Hairy root culture, also called transformed root culture, is a type of plant tissue culture that is used to study plant metabolic processes or to produce valuable secondary metabolites or recombinant proteins, often with plant genetic engineering.
Acetosyringone is a phenolic natural product and a chemical compound related to acetophenone and 2,6-dimethoxyphenol. It was first described in relation to lignan/phenylpropanoid-type phytochemicals, with isolation from a variety of plant sources, in particular, in relation to wounding and other physiologic changes.
Neorhizobium galegae is a Gram negative root nodule bacteria. It forms nitrogen-fixing root nodules on legumes in the genus Galega.
Neorhizobium huautlense is a Gram negative root nodule bacteria. It forms nitrogen-fixing root nodules on Sesbania herbacea.
EHA101 was one of the first and most widely used Agrobacterium helper plasmid for plant gene transfer. Created in 1985 in the laboratory of Mary-Dell Chilton at Washington University in St. Louis, it was named after the graduate student who constructed it. The EH stands for "Elizabeth Hood" and A for "Agrobacterium". The EHA101 helper strain is a derivative of A281, the hypervirulent A. tumefaciens strain that causes large, fast-growing tumors on solanaceous plants. This strain is used for moving genes of interest into many hundreds of species of plants all over the world.
Neorhizobium is a genus of Gram-negative soil bacteria that fix nitrogen. It was recently segregated from the genus Rhizobium. Neorhizobium forms an endosymbiotic nitrogen-fixing association with roots of legumes.
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Medina-Bolivar, Fabricio (4 December 2013). "Antioxidant Activity of Selected Stilbenoids and Their Bioproduction in Hairy Root Cultures of Muscadine Grape (Vitis rotundifolia Michx.)". Journal of Agricultural and Food Chemistry. 61 (48): 11744–11758. doi:10.1021/jf400760k. PMID 23668830.