Nectria radicicola | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Fungi |
Division: | Ascomycota |
Class: | Sordariomycetes |
Order: | Hypocreales |
Family: | Nectriaceae |
Genus: | Nectria |
Species: | N. radicicola |
Binomial name | |
Nectria radicicola Gerlach & L. Nilsson (1963) | |
Synonyms | |
Cylindrocarpon destructans Contents |
Nectria radicicola is a plant pathogen that is the causal agent of root rot [1] and rusty root. [2] Substrates include ginseng [3] and Narcissus. It is also implicated in the black foot disease of grapevine. It is of the genus Nectria and the family Nectriaceae. N. radicicola is recognizable due to its unique anatomy, morphology, and the formation of its anamorph Cylindrocarpon desructans. [4]
N. radicicola is currently distributed evenly alongside its primary substrates American ginseng, Panax quinquefolius, and Korean ginseng, Panax ginseng . [2] It occurs throughout North America and continental Asia, primarily Korea and China. It can alternate between growing with a host or remaining dormant as chlamydospores for years at a time if none is present. Because the spores are able to effectively overwinter in plant debris and soil, N. radicicola is not limited by seasonally colder climate conditions. [5]
N. radicicola is a species complex of organisms which target the roots of various species of ginseng, grapevines, and some young trees as their primary substrate. [6] [7] The primary vector of infection are the chlamydospores which might survive for years in the soil before detecting and subsequently infecting a new host organism. Upon infecting the host organism hyphae begin to grow inter and intracellularly which subsequently causes the plant tissues to begin to rot. More chlamydospores will form once the hyphae reach the surface of the host tissue where micro and macronidia will sprout and release the spores.
After contracting root rot from N. radicicola, the plant will begin to wilt and eventually become discolored, transitioning from red-orange to brown-black with an accompanying strong odor resulting from the rot. The discoloration and odor may be localized only to lesions on the base of the stem and roots or spread across most of the plant. The roots will eventually dry out and become scaly and shriveled. In time the infection may invite secondary infections to take hold in addition to that from the N. radicicola from non-pathogenic sources. [8] [2]
Rusty root usually presents as slightly raised rust-colored spots at the crown of the taproot which will then spread to cover part or all of the root. The symptoms are only present on the surface of the root however and the discolored spots can be scraped off to reveal healthy tissue beneath. Rusty root is a less severe disease than root rot, with a much lower chance of inflicting serious long-lasting damage or death on the host plant and is associated with the less aggressive strains of the N. radicicola complex. [2]
Research has shown that the virality of the N. radicicola is variable and highly dependent on the makeup of the double stranded RNA within the genotype. Phenotypic features which were closely related to virality such as laccase activity and sporulation were highly dependent on the amount and type of dsRNA present in the genome. This may indicate that the size of dsRNA present in a strain is a key indicator for viral success in different strains of the N. radicicola population. [9] [10]
It has been observed that rusty root and root rot may either be inflicted on host plants, specifically various forms of ginseng, after contracting N. radicicola. Due to the increased severity of a root rot infection over rusty root, the strains which cause root rot are considered to be the more aggressive of the variations. New research suggests that the symptoms may actually arise from two different species rather than just the N. radicicola but rather that It has been observed that rusty root and root rot may either be inflicted on host plants, specifically ginseng, after contracting N. radicicola and due to the added severity, the strains which cause root rot are considered the more aggressive of the variations. Research suggests that the symptoms may actually arise from two different species rather than just the N. radicicola. Ilyonectria mors-panacis may be responsible for the root rot while the N. radicicola might only result in the observed rusty root. As the name suggests, Ilyonectria mors-panacis is closely related to Nectria radicicola, also known as Ilyonectria radicicola, but the genetic discrepancies between plants observed with root rot and rusty root are significant enough that what was thought to be merely different strains might actually be classified as arising from two different species of fungus. [2]
Ginseng is the root of plants in the genus Panax, such as Korean ginseng (P. ginseng), South China ginseng (P. notoginseng), and American ginseng (P. quinquefolius), characterized by the presence of ginsenosides and gintonin. Ginseng is common in the cuisines and medicines of China and Korea.
The Panax (ginseng) genus belongs to the Araliaceae (ivy) family. Panax species are characterized by the presence of ginsenosides and gintonin. Panax is one of approximately 60 plant genera with a classical disjunct east Asian and east North American distribution. Furthermore, this disjunct distribution is asymmetric as only two of the ~18 species in genus are native to North America.
Fusarium wilt is a common vascular wilt fungal disease, exhibiting symptoms similar to Verticillium wilt. This disease has been investigated extensively since the early years of this century. The pathogen that causes Fusarium wilt is Fusarium oxysporum. The species is further divided into formae speciales based on host plant.
Phytophthora cinnamomi, also known as cinnamon fungus, is a soil-borne water mould that produces an infection which causes a condition in plants variously called "dieback", "root rot", or, "ink disease".
Alfalfa mosaic virus (AMV), also known as Lucerne mosaic virus or Potato calico virus, is a worldwide distributed phytopathogen that can lead to necrosis and yellow mosaics on a large variety of plant species, including commercially important crops. It is the only Alfamovirus of the family Bromoviridae. In 1931 Weimer J.L. was the first to report AMV in alfalfa. Transmission of the virus occurs mainly by some aphids, by seeds or by pollen to the seed.
Pseudomonas panacis is a Gram-negative, aerobic, motile with one or more polar flagella, rod-shaped bacterium. It derives its name from the fact that it causes rusty root lesions on Korean ginseng, as the ginseng genus is Panax.
Ceratocystis fimbriata is a fungus and a plant pathogen, attacking such diverse plants as the sweet potato and the tapping panels of the Para rubber tree. It is a diverse species that attacks a wide variety of annual and perennial plants. There are several host-specialized strains, some of which, such as Ceratocystis platani that attacks plane trees, are now described as distinct species.
Thielaviopsis basicola is the plant-pathogen fungus responsible for black root rot disease. This particular disease has a large host range, affecting woody ornamentals, herbaceous ornamentals, agronomic crops, and even vegetable crops. Examples of susceptible hosts include petunia, pansy, poinsettia, tobacco, cotton, carrot, lettuce, tomato, and others. Symptoms of this disease resemble nutrient deficiency but are truly a result of the decaying root systems of plants. Common symptoms include chlorotic lower foliage, yellowing of plant, stunting or wilting, and black lesions along the roots. The lesions along the roots may appear red at first, getting darker and turning black as the disease progresses. Black root lesions that begin in the middle of a root can also spread further along the roots in either direction. Due to the nature of the pathogen, the disease can easily be identified by the black lesions along the roots, especially when compared to healthy roots. The black lesions that appear along the roots are a result of the formation of chlamydospores, resting spores of the fungus that contribute to its pathogenicity. The chlamydospores are a dark brown-black color and cause the "discoloration" of the roots when they are produced in large amounts.
Phytophthora cactorum is a fungal-like plant pathogen belonging to the Oomycota phylum. It is the causal agent of root rot on rhododendron and many other species, as well as leather rot of strawberries.
Phytophthora nicotianae or black shank is an oomycete belonging to the order Peronosporales and family Peronosporaceae.
Fusarium redolens is a species of fungus in the genus Fusarium and family Nectriaceae. This species is a soil-borne plant pathogen in temperate prairies. It causes diseases such as root, crown, and spear rot, seedling damping-off, and wilting disease. It is a known producer of the alkaloids peimisine and imperialine-3β-d-glucoside, which has implications for traditional Chinese medicine.
Fusarium solani is a species complex of at least 26 closely related filamentous fungi in the division Ascomycota, family Nectriaceae. It is the anamorph of Nectria haematococca. It is a common soil fungus and colonist of plant materials. Fusarium solani is implicated in plant disease as well as human disease notably infection of the cornea of the eye.
Soil-borne wheat mosaic virus is a rod-shaped plant pathogen that can cause severe stunting and mosaic in susceptible wheat, barley and rye cultivars. The disease has often been misdiagnosed as a nutritional problem, but this has actually allowed in part for the fortuitous visual selection by breeding programs of resistant genotypes. Soil-borne wheat mosaic virus is part of the genus Furovirus. Members of this genus are characterized by rigid rod-shaped particles and positive sense RNA genomes consisting of two molecules that are packaged into separate particles that code for either replication, mobility, structure or defense against the host. The virus is spread by a fungal-like protist, Polymyxa graminis, whose asexual secondary and sexual primary cycles help the virus spread. The disease produces secondary symptoms from the root cell infection. The disease is a serious contributor to loss in crop yield.
Panax vietnamensis or Vietnamese ginseng is a species of the ginseng genus Panax. In Vietnam the species, prized in herbal medicine, is commercially very valuable and now considered threatened.
Cassava brown streak virus disease (CBSD) is a damaging disease of cassava plants, and is especially troublesome in East Africa. It was first identified in 1936 in Tanzania, and has spread to other coastal areas of East Africa, from Kenya to Mozambique. Recently, it was found that two distinct viruses are responsible for the disease: cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Both have (+)ss RNA genomes, belong to the genus Ipomovirus in the family Potyviridae, and produce generally similar symptoms in infected plants. Root rot renders the cassava tuber inedible, resulting in severe loss of economic value; therefore, current research focuses on achieving cultivars that do not develop the necrotic rot. This disease is considered to be the biggest threat to food security in coastal East Africa and around the eastern lakes.
Neonectria is a genus of fungi in the family Nectriaceae.
In biology, a pathogen, 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.
Bromovirus is a genus of viruses, in the family Bromoviridae. Plants serve as natural hosts. There are six species in this genus.
Cassava brown streak virus is a species of positive-strand RNA viruses in the genus Ipomovirus and family Potyviridae which infects plants. Member viruses are unique in their induction of pinwheel, or scroll-shaped inclusion bodies in the cytoplasm of infected cells. Cylindrical inclusion bodies include aggregations of virus-encoded helicase proteins. These inclusion bodies are thought to be sites of viral replication and assembly, making then an important factor in the viral lifecycle. Viruses from both the species Cassava brown streak virus and Ugandan cassava brown streak virus (UCBSV), lead to the development of Cassava Brown Streak Disease (CBSD) within cassava plants.
Phenylobacterium panacis is a Gram negative and rod-shaped bacterium from the genus of Phenylobacterium which has been isolated from the rhizosphere of a ginseng plant from the Hwacheon mountain in Korea.