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Tobacco Mosaic Virus TMV Infection Disease


Quickly understand tobacco mosaic virus disease

Everything in the world has two sides, and any object has a good side and a bad side. Tobacco is no exception. Tobacco is addictive, causing many smokers to become addicted to smoking. Not only is it a waste of money, but also a cigarette disease, so many people think that tobacco will only harm people's physical and mental health, and some even think that tobacco is harmless. Yili. In fact, this is just the disadvantage of tobacco. We cannot kill the beneficial side of tobacco just because we see the harmful side of tobacco.

Forever Existence of Tobacco

Tobacco can always exist in our lives because of its own truth. Tobacco, as a drug plant with a long history, has great medical value itself, it is of great medicinal properties, and can not only disinfect and kill Insect sterilization can also treat a variety of diseases, which is its advantage.
This is the root cause of its large-scale cultivation across the country, because it can bring huge economic benefits to the national society and promote economic development.
Today, the editor will tell you about tobacco mosaic virus disease.

This disease has already appeared in most areas, and the scope of influence is expanding.
This virus will reduce tobacco production and reduce the quality of tobacco, and also cause unnecessary economic losses to tobacco growers. Therefore, by reviewing information and combining practical experience, the editor will tell you about the types, specific causes and morbidity characteristics of tobacco mosaic virus disease, and then give treatment methods for these causes and characteristics.

Type of Virus TMV PMV CMV

The first is the type of virus, tobacco common mosaic virus disease (TMV), tobacco cucumber mosaic virus disease (CMV), tobacco potato Y virus disease (PMV) are all one of the tobacco mosaic virus diseases. Among them, the common mosaic virus is the earliest discovered plant virus, which is also called TMV. 

If the tobacco is infected with tobacco common mosaic virus disease, the structure of the mesophyll on the newly grown leaves, including the veins, are all colored The color of the leaves is lighter than normal leaves. 

The whole mesophyll vein structure is very obvious under the sunlight. The whole leaves look like translucent and very clear, and the chlorophyll of the leaves will be reduced, which will affect photosynthesis and cause the leaves to appear. In the case of different colors, the green is darker in some places, and the green is lighter in some places, and even yellowing occurs, and the edge of the leaves will curl to varying degrees.

Different infections have different infection symptoms. If the infection is lighter, the edge of the leaves will not curl, but the thickness of the leaves of the leaves will be significantly different. Some areas will be thicker and some areas will be thinner. Color There will be some differences in depth. If the infection is severe, the edges of the leaves will be markedly curled, the translucency will be more obvious, the color difference will be greater, and the leaves will be perforated and thinned, or even die. 
 
Tobacco Mosaic Viruses
Different Types of Viruses

TMV is mainly spread through poisonous fertilizers, man-made agricultural operations and diseases and insects

It enters the juice through the damaged gap and slowly infects the entire leaf tissue to cause infection.

The second is the cause and characteristics of the disease. All plants are easy to be infected with various diseases at the seedling stage, and tobacco is no exception. In addition, the time period from the beginning of tobacco switching is susceptible to disease, because of the bacteria

The survivability is very strong, coupled with the destruction of large-scale agricultural management, wind and rain, and the spread of diseases and insects will accelerate the spread of the virus and expand the spread of the virus.

In addition, the fertility of the land, the drainage system, and the weather temperature are all factors that affect the incidence. The poor productivity of the land, the lack of nutritional supplements, and the poor drainage system can easily cause tobacco disease.

The last is about the prevention and control methods. All plants are the same, there will be gaps in varieties, so tobacco is no exception.
In the early stage of cultivating and selecting varieties, you should choose excellent varieties, especially disease-resistant and excellent tobacco.
From the selection of the breed, it is not allowed to lose on the starting line, so that it can prevent the virus from eroding. The next step is the protection and management of tobacco seedlings. First, the seed bed will be important. When selecting the seed bed, try to stay away from other crop selection areas. 

The seed bed should be disinfected, sterilized and weeded to minimize the destruction of tobacco seedlings. 

During the transition period, avoid strong sunlight, water regularly and pay attention to drainage in rainy weather. Choose the right fertilizer for application. The organic fertilizer must be sprayed at the right time and in the right amount. There is also a scientific and reasonable rotation system.

Experiments on tobacco mosaic virus

Teaching problem: The experimental textbook on tobacco mosaic virus is very simple. I consulted "Genetics" edited by Liang Hong to understand the process of this experiment.

In 1956, the American scholar Fraemkel-Courat used the reconstruction experiment of tobacco mosaic virus (TMV) to prove that RNA is also genetic material.

This experiment was conducted with tobacco mosaic virus. TMV is an RNA virus. It has a cylindrical protein shell composed of many identical protein subunits. There is a single-stranded RNA molecule, which spirals between protein subunits along the inner wall.

So, in this RNA virus, is the genetic information on RNA, or on protein?

   1. Infection experiment

Shock TMV in water and phenol to separate viral RNA and protein to infect tobacco. The virus protein alone cannot infect tobacco. The viral RNA alone can infect tobacco and viral RNA enters the leaf cells. Breeding to produce normal virus descendants. The efficiency of RNA infection alone is poor. It may be due to the naked RNA, which is easily degraded by enzymes during the infection process. Treating RNA with RNase completely loses its infectivity.

2. Reconstruction experiment

Many strains of TMV can be distinguished according to the difference between the host plant and the difference in the formation of a lesion on the plot of the host plant. For example, there are two strains whose coat proteins are different: the coat protein of strain S does not have histidine and methionine, while strain HR contains these two amino acids.

Frenkel-Culante used the separation and polymerization method to first obtain the protein coat of S strain and the RNA of HR strain, and then combine them to form a hybrid virus, with the shell of S strain, which can be used by antibodies Inactivated, but not affected by antibodies made to the HR strain. When the hybrid virus is used to infect tobacco, the lesions are always the same as those of the RNA donor, so it is obvious that the second generation virus particles have the HR strain RNA and protein coats of HR strains. 

The HR strain protein and S strain RNA are combined to form a hybrid virus. Infecting tobacco with the reconstructed virus had similar results. So we can say that in viruses that do not contain DNA, the genetic information necessary to replicate and form new virus particles is carried on RNA.

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