植物干细胞 z-bo 2020-10-23 336

　　Plants can grow indefinitely because they contain meristems composed of plant stem cells. These plant stem cells have a unique ability to transform themselves into various specific cells that make up plants, and when appropriate Divide and generate any type of new cells as needed. The meristem exists at the top of all plants, allowing them to grow new stems or roots. In trees, meristems are also present in the trunk, which can increase the circumference of the trunk.

　　Since the 1950s, people have known that the meristem at the top of the plant, the shoot apical meristem (SAM), has an extraordinary ability: even if other parts of the plant are completely infected by the virus, they will It can maintain a virus-free state when producing specific daughter cells. This situation is not only for one or even several viruses, but for all kinds of viruses.

　　Since then, scientists and farmers have used the most important part of the plant's anti-virus ability to cultivate new plants from infected donor plants, but they will not pass the virus to the cultivated plants. They only need to cut off a small part of the top of the plant, culture it in a test tube or petri dish for a period of time, and then repeat it several times. The cut plant part usually grows pathogen-free plants.

　　In a new study, researchers from the University of Science and Technology of China, Guangzhou University, Sichuan University, and Heidelberg University in Germany provided new insights into this incredible ability. The relevant research results were published in the Science Journal on October 9, 2020. The title of the paper is "WUSCHEL triggers innate antiviral immunity in plant stem cells". The corresponding authors of the paper are Zhaoxia Tian and Zhong Zhao from the University of Science and Technology of China.

　　These researchers inoculated cucumber mosaic virus (CMV) onto Arab mustard (thale cress) plants and observed what happened.

　　When the cucumber mosaic virus spread to SAM, they noticed that the virus stopped before reaching a WUSCHEL-expressing region (hereinafter referred to as WUSCHEL expression region). By carefully observing the distribution of the regulatory protein WUSCHEL in this area, they found that more WUSCHEL appeared where the virus tried to gain a foothold after inoculation. As an extremely important protein, WUSCHEL plays a key regulatory role in determining the fate of stem cells in the early stages of plant embryo development. It is also responsible for supervising SAMs, keeping them in an undifferentiated state, and determining that they will What kind of daughter cells are produced.

　　They then inoculated the cucumber mosaic virus directly into the stem cells of Arabidopsis thaliana and found that the virus only spread in the latter area. Zhao said, “A chemical called dexamethasone can induce the WUSCHEL protein in the plants we tested. Therefore, next, we inoculate Arab mustard with more cucumber mosaic virus, and then some of them Plants are treated with dexamethasone, and some plants have not received this treatment.” Of the Arab mustard plants that did not receive dexamethasone treatment, about 89% of the plants were infected with the virus, but in the Of the Arabidopsis plants, 90% of the plants have not been invaded by this virus.

　　How did WUSCHEL defeat this virus? These researchers found that the function of WUSCHEL protein is to inhibit the production of cucumber mosaic virus protein.

　　Viruses cannot make their own proteins, but rather hijack the body’s protein assembly line to produce their own copies of the virus. The WUSCHEL protein, which plays a great role in regulating SAM, has essentially frozen all protein production-whether it is the plant's own protein production or the protein production when it is hijacked by the virus-thus preventing the replication of the virus.

　　Zhao said that genes similar to those in Arabidopsis that directly produce the WUSCHEL protein are very common in the plant kingdom, so these researchers are very interested in "whether this strategy can be applied to breeding to obtain broad-spectrum virus-resistant crop varieties in the future." interest.