马铃薯X病毒组是什么?

Question

如题所述

Answer 1

1. Potexvirus group，led by Liang Xunshang，is a group of viruses with single-stranded RNA (ssRNA)、non-enveloped, rod-shaped particles measuring 470-580 nanometers in length. The viral genome has a nucleic acid content of 5% to 6% and a molecular weight of 2.1×10^6. The protein content is 94% to 95%, with a molecular weight of 18-28×10^3.
2. The Potexvirus group is named after the English word "potato" (马铃薯), with "X" being the first letter of the word "virus" in English, and the term Latinized. The typical member of this group is Potato virus X (Potato virus X), and other members include White clover mosaic virus (White clover mosaic virus), Narcissus mosaic virus (水仙花叶病毒), Cymbidium mosaic virus (建兰花叶病毒), Cactus virus X (仙人掌病毒X), and Cassava common mosaic virus (木薯普通花叶病毒) among others.
3. Under an electron microscope, the virus particles appear as curved rod-like structures, about 13 nanometers in diameter and 470-580 nanometers in length. In optical microscopy, fibrios inclusion bodies are often observed within the plant cells, sometimes band-like inclusions.
4. The internal RNA chain of the virus particle is helical对称构型, with a pitch of approximately 3-4 nanometers. The RNA base composition ratio is 15.5-25% guanine, 26.4-34% adenine, 23-30.3% cytosine, and 20.6-26% uracil.
5. The positive-sense single-stranded ssRNA molecule of the virus has a cap-like structure at its 5'-end (m7G5'ppp5'Gp...) and does not have a poly(A) tail at its 3'-end. The outer shell of the virus particle is composed of multiple peptide chains.
6. The virus particle has a molecular weight of 35×10^6 and a sedimentation coefficient (S20·w) of 115-130s. It has a density of approximately 1.31 g/cm^3 in cesium chloride. The absorption spectrum shows a ratio of 260 nm/280 nm of 0.86-1.4, and the isoelectric point is pH 4.4-5.3. This group of viruses is relatively stable.
7. For example, Potato virus X can remain infectious after being immersed in hot water above 68-75℃ for 10 minutes or diluted to 100×10^4 times. The virus in the extracted juice of diseased leaves can survive for more than a year at room temperature.
8. This group of viruses has a narrow range of host plants and often causes mosaic symptoms, often accompanied by dwarfing. For example, Potato virus X causes yellow-green or light yellow mottling symptoms on potato leaves, and strong strains can lead to leaf wrinkling and curling. However, on more resistant varieties like "Baron," there may be no obvious symptoms or only mild mosaic symptoms. If it infects temperature-sensitive reaction potato varieties such as "Epicure," it can cause severe necrosis spots on the top leaves and complete dwarfing of the whole plant.
9. This group of viruses is easily transmitted through contact friction between infected plant juices and can also be transmitted by non-persistent methods such as aphids.
10. Potato virus X can be distinguished based on symptoms into ring spot, mottle, and latent symptom strains; and based on cross-protection reactions, it can be divided into X1, X2, X3, and X4 strains. This group of viruses has strong antigenicity, and most members can be used to prepare high-titer antisera for identification.
11. Potato virus X disease is a common and widespread disease in potato cultivation areas, which can cause significant losses in potato production in areas with highly susceptible varieties. In the field, it often causes complex infections with other viruses, leading to greater losses. Since the 1970s, countries have successively carried out research on virus-free culture and breeding of virus-free seed potatoes, and established corresponding systems and measures, which have played an important role in reducing the harm caused by potato virus diseases.