Tulips -- the virus hidden behind beauty


Tulips are loved by many people for their bright colors and different flower shapes. It has the reputation of "Queen of Flowers" and is the national flower of the Netherlands and Turkey, which means victory and beauty. However, there are actually many crises hidden behind the beauty of tulips. For example, it once caused the "Tulip Bubble" incident in the Netherlands, which once severely damaged the Dutch economy and gave the economics community a unified understanding of the bubble economy. Another example is the popular striped tulip, whose beautiful stripes are caused by mosaic virus. While mosaic virus makes tulips more beautiful, it also makes them more fragile. Especially when this virus infects food crops, it may cause grain harvest failure.

Beautiful and fragile striped tulips

Among the various types of tulips, the most expensive and most popular are the varieties with mottled stripes on the petals. These stripes are either in the shape of flames or in the shape of broken feathers. They are colorful, colorful and unique. People are flocking to this type of tulip and have developed many popular varieties, such as Viceroy, Semper Augustus, etc. However, people's beloved striped tulip is actually a "sick beauty". The stripes on its beautiful petals are actually caused by viral infection.

Just as humans can become sick due to viral infections, plants can also show a variety of symptoms due to viral infections. The stripes on the petals of striped tulips are caused by the tulip break virus that infects the tulip bulbs. The reason why this virus can cause complex mottled stripes to appear on tulip petals is because it affects the synthesis of anthocyanins in tulip cells. Anthocyanins are red or blue pigments. Cells that can synthesize anthocyanins normally will appear dark red; while cells infected by the virus will appear lighter yellow because they cannot synthesize anthocyanins smoothly. Healthy cells and diseased cells are staggered in the petals, creating intricate patterns.

Although the flowers of striped tulips are beautiful, the entire plant grows slowly. Not only will the bulbs shrink, the flowering period will be shorter, the number of flowers will be less, and many plants will not bloom again in the second year. How can these breeds be passed down? Scientists have discovered that if the bulbs of broken tulips and the bulbs of ordinary tulips are grafted together, the ordinary tulips can produce broken-colored flowers. This is because viruses can be transmitted from diseased bulbs to healthy bulbs when the damaged surfaces of two bulbs come into contact during the grafting process.

In addition to tulips, viruses on many fruit trees can be transmitted through grafting. The prevention and control of viral diseases is more difficult and difficult than the prevention and control of other infectious diseases. Therefore, people need to pay special attention when using grafting technology.

The spread and harm of viruses in the plant kingdom

Viruses are a very tiny life form with a very simple structure. They can pass through filters that bacteria cannot. People generally need an electron microscope to observe them. The reason why viruses are not called organisms is that they do not have a cellular structure and a complete metabolic system. Except for prions, viruses all contain a single type of nucleic acid (DNA or RNA), and some viruses have an outer membrane and a protein coat. Only by infecting host cells can the virus show its vitality - releasing its nucleic acid while infecting the host cell and later, and then multiplying by means of nucleic acid replication. In other words, once it leaves the host cell, the virus becomes a chemical substance without any life activity and cannot reproduce itself.

Viruses are widely distributed in nature and can infect bacteria, fungi, plants, animals and humans, causing different forms of diseases. In the natural environment, the virus needs to find a "wound" in order to take advantage of it and spread. The organisms that cause the most wounds to plants are insects, such as aphids and planthoppers, whose mouths can easily pierce the surface of plants to suck out their juices. If a plant is infected with a virus, the virus can enter the insect's body along with the sap it inhales, and then infect those plants when the insect sucks the sap from other plants. Studies have shown that about 80% of plant viruses rely on specific insects as transmission vectors, and aphids are the "hitchhikers" that viruses especially like to hitch a ride on.

In nature, the impact of viruses on plants is often negative or even fatal. Among seed plants, most viruses are found in angiosperms; viral diseases on woody plants are far less common than on crops; and among crops, almost none are immune to virus infection. The vast majority of viral diseases are systemic infections, and local infections are rare. That is to say, the virus will expand from the infection point to other plant tissues or even the entire plant. The symptoms are most obvious in leaves and twigs, sometimes in fruits, but rarely in seeds. The main sources of infection of viral diseases are live host plants and insects. Grafting, cuttings, and tiller propagation are important ways of spreading and inoculating viruses.

Take rice as an example. Rice is very susceptible to viruses. Rice stripe leaf blight is known as a cancer on rice because of its rapid spread and great harm. Diseased rice will grow yellow-green striped leaves, the entire plant will grow slowly, and the heading will be deformed. Once this disease breaks out, rice production will be significantly reduced. Rice stripe blight is caused by rice stripe blight virus, which is mainly transmitted by the bovine planthopper. To combat the virus, farmers applied large amounts of pesticides to rice fields. In the beginning, the insecticidal effect was very significant; but later, the planthoppers became resistant to the insecticides, the insecticides became less and less effective, and the environmental pollution problem became more and more serious.

In order to solve this problem, scientists have studied in depth the response of rice to virus infection. To put it simply, the reaction process is roughly divided into two steps: first, after entering the rice cells, the virus will find a way to use the rice's "production line" (DNA replication and protein synthesis system) to produce hundreds or thousands of small viruses; then, through The "highway" that transports nutrients in rice (the conductive tissue of rice), the virus will be transported throughout the body of the rice. In this way, when the bovine planthopper comes to feed, the virus can be transmitted to another rice plant through it. On. From this point of view, the main task of preventing and controlling virus infection is to transform the "production line" and "highway" of plants, so as to not affect the growth of the plants themselves, but also to block the proliferation and spread of viruses in their bodies to the greatest extent.

On one side are the enchanting striped tulips, on the other side are the failed rice crops. Plant viruses really make people love and hate them. It seems that people's understanding of viruses is far from enough. How to make viruses "abandon evil and embrace good" and coexist harmoniously with humans requires more in-depth research by scientific researchers.