Question

The filterable property of tobacco mosaic virus (TMV) was shown by
A. Ivanowsky
B. Beijerinck
C. Stanley
D. Winogradsky

Answer 1

Tobacco mosaic virus (TMV) is a positive-sense single-stranded RNA virus species in the genus Tobamovirus that infects a wide range of plants, especially tobacco and other members of the family Solanaceae. The infection causes characteristic patterns, such as "mosaic"-like mottling and discoloration on the leaves. TMV was the first virus to be discovered.

Complete answer: In 1886, Adolf Mayer first described the tobacco mosaic disease that could be transferred between plants, similar to bacterial infections. In 1892, Dmitri Ivanovsky gave the first concrete evidence for the existence of a non-bacterial infectious agent, showing that infected sap remained infectious even after filtering through the finest Chamberland filters. Later, in 1903, Ivanovsky published a paper describing abnormal crystal intracellular inclusions in the host cells of the affected tobacco plants and explained the connection between these inclusions and the infectious agent.
The tobacco mosaic virus has a rod-like appearance. Its capsid is made from 2130 molecules of coat protein and one molecule of genomic single-strand RNA, 6400 bases long. The coat protein self-assembles into the rod-like helical structure around the RNA, which forms a hairpin loop structure. The protein monomer consists of 158 amino acids which are assembled into four main alpha-helices, which are joined by a prominent loop proximal to the axis of the virion.
The first symptom of this virus disease is a light green coloration between the veins of young leaves. This is followed quickly by the development of a "mosaic" or mottled pattern of light and dark green areas in the leaves. Rugosity may also be seen where the infected plant leaves display small localized random wrinkles. These symptoms develop quickly and are more affected by younger leaves. Its infection does not result in plant death, but if infection occurs early in the season, plants are stunted.

Hence, the correct option is (A) Ivanowsky

                                                                      TMV structure  

Note: Beijerinck coined the term "virus" to indicate that the causal agent of tobacco mosaic disease was nonbacterial. The tobacco mosaic virus was the first virus to be crystallized. It was achieved by Wendell Meredith Stanley in 1935 who also showed that TMV remains active even after crystallization.