A single-stranded RNA virus with a positive sense is called the Tobacco Mosaic Virus(TMV). The virus is a member of the Solanaceae family and the genus Tobamovirus.
Introduction and History of TMV
One of the earliest plants in which it was discovered in the 1800s is the source of the name for the tobacco mosaic virus. but it can infect more than 350 different plant species. In 1886, Adolph Mayer first started studying the TMV. Martinus Willem Beijerinck proposed in 1898 that a contagious substance he dubbed a virus was the source of the tobacco mosaic virus. It was the first virus crystallized by W.H. Stanley in 1935. The first images of TMV taken with an electron microscope were taken by Kausche in 1939.
Host and pathogen of Tobacco Mosaic Virus
TMV most frequently affects tomatoes, although it can also infect pepper, potato, apple, pear, cherries, and a variety of weeds. various hosts may exhibit various symptoms. Cucumber, lettuce, beetroot, pepper, tomato, petunia, jimson weed and horse nettle are just a few of the crops, ornamentals and weeds that TMV affects.
Significance of TMV
First plant virus to be identified as a disease-causing agent. most prevalent in 13 states, including Andhra Pradesh, Assam, Maharashtra, Odisha, Tamil Nadu, and Uttar Pradesh, where tobacco crops are grown. the first virus whose protein coat’s 158 amino acids were entirely sequenced. The first plant RNA virus whose entire genome was sequenced and for which monoclonal antibodies were created was TMV.
Economic loss
It globally reduces quality and quantity by up to 50% and up to 30%, respectively. Due to the widespread cultivation of resistant tobacco types, it currently loses 1% of global productivity. It can accommodate many hosts. It resulted in a 20% reduction in tomato yield.
Distribution
With an output of 800 million kgs per year, India is the second-largest tobacco producer. It is available everywhere. In many different plants, the same virus is present. The most significant of the more than 20 viral illnesses that affect tobacco is a mosaic disease.
Symptoms and signs of Tobacco Mosaic Virus
About 10 days after infection, symptoms start to show up. The plants typically do not perish, although growth may be severely stunted. Certain TMV strains in tomatoes might result in distorted fruit, uneven fruit colour, and delayed ripening.
The host plant, the age of the infected plant, the environmental factors, the virus strain, and the genetic makeup of the host plant all affect the specific symptoms. On the other hand, typical symptoms include mottling, or mosaic-like spots, on the leaves, as well as curling and yellowing of the plant tissues.
Transmission of Tobacco Mosaic Virus
‘Mechanical’ wounds created by contaminated hands, clothing, or equipment like pruning shears and hoes are the most common way that the tobacco mosaic virus spreads from plant to plant. This is due to the fact that most plant cells have very high quantities of TMV. Tiny leaf hairs and some outer cells are unavoidably destroyed when plants are handled, causing sap to spill over hands, tools, and clothing.
Infected plants’ seeds may also have the virus on their seed coats. The likelihood that the virus may contaminate the seed coat during seed harvest increases with the mother plant’s infection age. The virus may infect the seedling during the germination/emergence phase or through tiny incisions brought on by transplanting and handling.
Pathogen Biology
Tobacco, tomato, and other solanaceous plants are hosts for TMV Tomato losses, however, have been recorded to reach 20%. Furthermore, low fruit quality could make the harvest less valuable in the commercial fresh market. Within the genus Tobamovirus, TMV is the type member of a significant group of viruses TMV virions, which are rod-shaped virus particles, with dimensions of roughly 300 nm × 15 nm.
The 2130 copies of the coat protein (CP) that surround the RNA molecule with around 6,400 nucleotides make up a single TMV particle.
Disease Cycle and Epidemiology
When an infected leaf brushes up against a healthy plant’s leaf, TMV is very easily spread by contaminated instruments and sometimes by workers whose hands become contaminated with the virus after smoking cigarettes. A damaged plant cell serves as a TMV point of entry. In cool weather, symptoms could be less noticeable. Because of this, infected seedlings could not show symptoms until they were placed in a warm environment.
TMV Management
Buy plants that are virus-free. Eliminate any weeds since they could contain TMV. Clean the benches and the greenhouse framework of all crop debris. With plants exhibiting the aforementioned signs, wait for a diagnosis. Throw away diseased plants. Tools should be disinfected by soaking them in a disinfectant for at least 10 minutes.
Thoroughly rinse with tap water. Use one of these materials to thoroughly wipe out door knobs and other greenhouse structures that may have become contaminated. instead of vegetative reproduction, use seed propagation. After handling tobacco products or plants that have TMV on them, thoroughly wash your hands.
Consider each greenhouse to be an independent building, complete with bins, equipment and safety clothing. Moving these objects between units is not advised. After handling tobacco products or plants with TMV, thoroughly wash your hands with the advised disinfectants, such as carbolic soap or a solution of non-fat milk powder at 20% weight/vol, 10% bleach, and 70% ethanol. Make sure the solutions are brand new and change them frequently.
1Hafiz M Rizwan Mazhar, 2Dr. Muhammad Atiq and 3Muhammad Ehetisham Ul Haq
- 1Nuclear Institute of Agriculture and Biology (NIAB), Faisalabad,
- 2 University of Agriculture, Faisalabad
- 3Ayub Agricultural Research Institute, Faisalabad
