A common orchid virus
1. Cymbidium mosaic virus
Cymbidium Mosaic Virus for short CyMV (1) Diseases Orchid plants infected with the Cymbidium mosaic virus often have a tendency to develop gangrenous disorders such as black gangrene spots and gangrene stripes. In addition to gangrene in the leaves and stems, the diseased plants also produce gangrene in the flower parts, which is a unique condition of the Cyclops virus. Orchid species that are susceptible to disease are reported to be blue, Jiadelialan, Wenxinlan, Hutoulan, Vanda, and Phalaenopsis. Bad freckle sometimes occurs only on the lower surface of the leaves but does not occur on the upper surface. This phenomenon occurs in all species of Oncidium, Dendrobium, Vanda, and Phalaenopsis and is often mistaken for fungal infections by cultivated people. Plants of orchids that are partially infected with the Clandulina mosaic virus, such as Hulotsia, Juvenile Orchid, Oncidium, and Phalaenopsis, may also develop yellow-green mottled patterns of embossing or yellowing strips. In addition, some orchid species do not show any identifiable diseases after infection.
(2) Viral Characteristics and Transmission Patterns Cymbidium mosaic virus is a type of potato virus virus (potex virus). Although the stability of the genus virus outside the cell is not as good as that of the tobacco mosaic virus genus, it is also a very stable genus of known viruses. The granules are slightly flexible and have a length of about 450 nm. The extracellular heat-resistant temperature is 60°C to 70°C, and they can survive for 25 days at room temperature.
At present, no vector insects have been found that can spread the virus, and the route of transmission is exactly the same as the Tetranychiditis viridis virus. The viruses are invaded and infected by root mechanical wounds.
2. Tequila ring spot virus
OdontoglossumRingSpotVirus
The abbreviation ORVS (1) According to the report, more than 20 species of orchids that can infect Tequila ring spot virus are reported. Different orchids or orchids produce different conditions. Orchid species such as Phalaenopsis, Oncidium, Carteran, Cymbidium, Four Seasons Blue, and Solanaceae are often susceptible to Tetranychidonic ring spot virus infection, especially the Phalaenopsis. The earliest documented condition in the literature of the Saccharornia virescens ring spot virus was the ring spot, with the addition of mottling, striped markings, yellowing stripes, flower streaks, and even gangrene disorders. Among these disorders, the most common are ridges and stripes. In addition, some species of orchids do not show signs of illness after infecting the Tooth orchid ring-spot virus. This phenomenon is particularly common during the seedling stage of Phalaenopsis and Oncidium. Infected plants usually wait until the first flowering before they gradually develop symptoms. In addition, artificially cultivated orchids in the orchids and C. hirsutella virus complexed with the same orchid strains are extremely common. The effects on the blue plants are additive, and the illness is far more serious than the single virus infection. .
(2) Viral Characteristics and Transmission Modes Tetranychis vivarium virus is a species of Tobamovirus. The particles are short rods and have a length of about 300 nm. The common characteristic of this genus virus is that it is extremely stable in nature and has strong heat resistance outside the host cell, and it can survive for quite some time at temperatures as high as 95°C. According to reports by Japanese scholars, Tetranychis vivarians virus can survive for more than 10 years outside the cell at 20°C, which is an extremely contagious virus. The virus can only invade plants through mechanical wounds. Therefore, during tissue culture or greenhouse cultivation management, all operations that may cause surface wounds, including cutting pedicels, pruning, and even friction between plant leaves, may become viral infections. Way. As of yet, it has not been confirmed that Viola lingzhi can be transmitted by any specific vector insects. However, any insect or small animal that may cause mechanical damage on the orchid plant, such as cockroaches, snails, etc., will increase the possibility of ring tooth spot virus infection and should be guarded against.
3. Courgette mosaic virus
CucumberMosaicVirus referred to as CMV (1) illness The earliest record of the infection of orchids with cucurbit mosaic virus was found on the Phalaenopsis orchid. The disease recorded at the time was the appearance of yellowing stripes parallel to the veins on the leaves of the plants. The squash mosaic virus also produces fading or streaks in the petals of the safflower line of phalaenopsis. In addition, the infection of the squash mosaic virus was found in the specimen of Oncidium. Specimen leaves showed inconspicuous markings, and yellow stripes parallel to veins were faintly visible, but the size of the plants did not differ from normal plant size.
(2) Viral Characteristics and Transmission The squash mosaic virus is a species of the genus Cucumovirus. The particles are spherical particles with a diameter of 28 nm. The host range of this virus is extremely wide, and it can infect more than 800 species of plants in 365 genera of 85 families. Most of the important cash crops in many parts of China have records of infection with the squash mosaic virus, and its population is extremely common in the field. This virus can be infected by a wound caused by mechanical friction. In the field, locusts are mainly transmitted in a non-persistent way. Because there are numerous locust species that can transmit the squash mosaic virus, the distribution of this virus is very widespread.
The best way to control orchid virus disease is to prevent its introduction before the disease occurs, that is, to thoroughly understand all possible transmission routes and sources of the virus, and then to completely block the virus so as to prevent the introduction of viruses.
1. Pathways for infecting viruses during orchid production.
(1) If a virus-infected plant is used as a parent for pollination, the seedling is subjected to aseptic seeding to propagate seedlings. The susceptible fruiting tissue and villi contain a high concentration of virus, which can contaminate the seed during sowing. Culture medium. Since both Tetranychis viciae virus and Cymbidium mosaic virus are extremely stable viruses, they can survive long outside the cell. After the orchid seeds germinate, the virus infects some of the seedlings by the wound invasion caused by human transplantation operations. These seedlings have become the source of virus infection and continue to pollute other plants during subculture. Even in the process of ripening and planting of seedlings, they become a source of virus pollution and are transmitted to other orchid seedlings.
(2) Since the virus-infected plant meets the market requirements, the operator conducts the meristem culture without virus test, and the large number of cloned cloned seedlings results in the propagation of the seedlings carrying the virus.
(3) Although the operator screened the parents of good traits for virus testing, these parents were just in the time of infection. Therefore, the virus concentration in the tissues was low or unevenly distributed. The test results were mistaken for the absence of virus infection in these parents. Colonies were cloned with these parents and the seedlings were caused to carry the virus.
(4) Parents with good traits were not infected with the virus but were contaminated with the virus during tissue culture. If the contaminated seedlings are contaminated by the virus during the mother bottle period, subsequent seedlings will carry all the virus. According to investigations, the procedures and techniques used during the operation cannot completely avoid virus contamination, which may lead to mutual infection among different batches of orchid seedlings.
2. Operating methods that may cause virus infection.
(1) Improper tool sterilization methods: The operating tools used in tissue culture, such as dumplings and scalpels, must undergo sterilization procedures to prevent bacterial and fungal infections. Therefore, operators can use different methods according to their own habits. Sterilization method. Traditionally, high temperature sterilization has been used, such as dry heat sterilization using a high temperature oven, moist heat sterilization using a high pressure sterilizer, and flame sterilizing method used in a sterile operating table.
Due to the extremely stable nature of Tooth Orchid Ringspot Virus and Cymbidium Mosaic Virus, if there is no appropriate and effective extermination method, this virus is very likely to have long-term contamination of countertops or tools that contaminate the sterile operating table, and even includes contaminated operators. The hands and clothing have the opportunity to indirectly infect the tissue culture seedlings.
(2) Contamination of the Petri dish: In addition to the use of an aseptic table for the transmission of tissue culture seedlings, the staff also uses a culture dish or support to isolate the tissue culture seedlings and the sterile operating table during the operation process. Direct contact with the tabletop. If it is used improperly, it will cause contamination between seedlings of different batches. Strictly speaking, the culture dish must be replaced with different batches of seedlings. This is because if the previous batch of seedlings was infected with the virus, it could contaminate the surface of the dish, and using the contaminated dish again would cause the next batch of seedlings to also be infected by the virus.
(3) Workers' negligence and bad habits: The negligence or unhealthy habits of the staff during the operation may increase the chance of virus infection in tissue culture. For example, when the flame sterilizing tool is used, the draft is incomplete, or when the change of the culture dish is not performed in time, it is a key factor for the virus infection of the tissue culture seedlings.
Managers can take measures to train employees, cultivate their professionalism, strengthen quality control and other measures to reduce the virus infection rate of seedlings.
3. The tissue culture seedlings were not infected with the virus, but were infected by the virus during removal from the bottle.
According to investigations, even if the sub-seedlings are not infected with the virus in the bottle, if a stringent precautionary measure against viral infection is not taken during the cultivation of the removed bottle, infection may still occur.
These common mistakes include: (1) After the operator removes the seedlings from the bottle, they are placed in a container to wash the residual medium or treated with a protective agent. In this case, if the seedlings of different batches are treated in the same container, some batch numbers When the seedlings carry the virus, the residual virus will contaminate the surface of the container, resulting in virus infection when the next batch of seedlings is reprocessed.
If some individuals in the same batch of seedlings are infected by the virus, when all the seedlings are treated in the same container, other individuals will also be infected.
(2) The table tops, tools, or workers' hands that are used in the seedling planting operations may all come into contact with virus-carrying seedlings during the transplantation process and suffer from virus infections, and thus become vectors for spreading the virus.
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