Viruses in Plants Study Materials

Viruses in Plants Plant viruses differ in several ways from viruses that attack animals or bacteria. One of these differences is the penetration mechanism virus into host cells. Plant viruses can only enter plant cells through mechanical wounds or insect vectors. This is caused by plant viruses not having penetration tools to penetrate plant cellwalls. On the other hand, most viruses that attack animals and bacteria can penetrate directly through cell membranes, such as bacteriophages (viruses that attack bacteria) which have penetration tools that can penetrate bacterial cell membranes. 1. Viruses as plant pathogens Mosaic disease in chili plants, Disease in passion fruit plants. 2. Viruses as insect pathogens NPV (Nuclear Pholyhedrosis Virus) - the host insects of NPV are Sl-NPV (for Spodoptera litura), Se-NPV (for S. exigua on shallot plants) and Ha-NPV (Helicoverpa armigera on tomato and corn plants). 3. Viruses as vectors 4. Viruses as cross protection Classification of plant viruses can be based on: 1. type of DNA or RNA virus nucleic acid 2. number of single or multiple nucleic acid threads 3. presence or absence of lipoprotein envelope 4. particle shape 5. chemical nature, vector, host 6. Serology. Viruses in Plants: 1. Tobacco Mosaic Virus (TMV) Causes of mosaic disease in tobacco, included in the (+) ssRNA group, family: Virgaviridae, genus Tobamovirus, rod-shaped particles, 300μm long and 15μm in diameter, has several strains, transmitted mechanically, tobacco mosaic virus can survive for years in tissue dried tobacco, in the stalks and root tissue of plants previously attacked by mosaics. Tobacco, pepper and eggplant plants are host plants for the virusTobacco Mosaic Virus(TMV). Tobacco mosaic disease is caused by several strains of the virus which cause slightly different symptoms. As in the Vorstenlanden tobacco area, the so-called "ordinary" mosaic disease causes chlorosis between the veins of the leaves, "bumpy" mosaic causes the parts to turn dark green.becomes curved, so that the leaf surface is uneven, and the "hard" mosaic causes the leaves to become very curly. One alternative control to reduce Tobamovirus infection is to induce systemic plant resistance. Induced systemic resistance is characterized by Pathogenesis Related Protein (PR-Protein) as a resistance gene molecule, for example peroxidase. 2. Cucumber Mosaic Virus (CMV) This virus is round, 29 nm in diameter - has no envelope, the genome consists of RNA, single-stranded, belongs to the (+) ssRNA group, family: Bromoviridae, genus Cucumovirus. This virus also infects other vegetables such as pumpkin, melon, peppers, beans, tomatoes, carrots, celery, lettuce, spinach, and beets - transmitted mechanically, by aphids through the mouth (stylet) Aphis craccivora, Myzus persicae - can be transmitted in seeds and by the parasitic weed, putri tali (Cuscuta sp.). 3. Potato virus Y PVY belongs to the (+) ssRNA group, family Potyviridae, genus Potyvirus, in the form of a filament with a length of 750 nm; diameter 11-15 nm. PVY is transmitted by the tick vector Myzus persicae, PVY can infect tobacco, tomatoes and pepper. Aphids only need to feed on virus-infected plants for about 20 seconds. PVY can be carried from one potato plant to another via infected seedlings. PVY can infect tobacco, tomatoes and pepper. Potatoes are infected with PVY, leaves are infected with PVY. 4. Rice Tungro Bacilliform Virus (RTBV) The cause of tungro disease in rice, belongs to the dsDNA group, family Caulimoviridae, genus Tungrovirus, transmitted by the green planthopper (Nephotettix virescens), N. virescens can acquire RTBV in 30 minutes during an 8-hour feeding period and can maintain its infectious capacity for up to 7 days. 5. Tomato Spotted Wilt Virus (TSWV) TSWV is included in the (-)ssRNA group, family Bunyaviridae, genus Tospovirus Tospovirus is transmitted by thrips (order: Thysanoptera) which can infect more than 13 types of viruses, TSWV can infect moreof 1000 plant species and causes significant economic damage to many agronomic and horticultural crops. 6. Tomato Yellow Leaf Curl Virus (TYLCV) The virus that causes curly yellow disease on tomato plants, belongs to the ssDNA group, Geminiviridae family, Begomovirus genus, is transmitted by insect vectors from the Hemiptera order, namely whiteflies or whiteflies (Bemisia tabaci). The primary host for TYLCV is tomato, and other plant hosts are eggplant, potato, tobacco, beans, and peppers. Symptoms are curling leaves (upward), spots, reduced leaf size, stunted plants, and flower drop, which greatly reduces fruit yield.