University:
Michigan State University
Course:
MIC 413 | Virology
Academic year:

2024
Views:

149

Pages:

1
Author:

Vernanda G.

Physiology of Plants Attacked by Viruses Plant viruses cannot penetrate directly to start infection of host plant cells without assistance that can deliver the virus into the cytoplasm of plant cells. Plant viruses can only enter plant cells through wounds that occur mechanically or are caused byvector(insects, mites, nematodes or fungi). Virus infection on the leaf surface occurs in epidermal cells. Virus particles enter through small wounds that do not cause cell death. After entering the host tissue, the virus will shed its coat. The nucleic acid from the virus will join the plant's genetic information system, so that it not only replicates to form its own RNA but also determines the formation of viral proteins. To be able to infect plants, a high concentration of virus is needed (105 virions). Diseased plants will always contain viruses throughout their life, so they are always carried to plants resulting from reproduction, especially vegetative reproduction.Virus infection in plants depends on virus synthesis, because infection will not occur if the virus cannot multiply in the host. After the virus enters the cell and comes into contact with the cytoplasm of a sensitive plant cell, the virus becomes attached to the cell. To cause infection, the RNA must be released from the protein coat. The release of nucleic acids took place approximately 1 hour after inoculation. The viral protein is released due to the enzyme activity of plant cells because viruses do not have enzymes. The protein coat that has been broken down is left in the cell and is used in the cell's synthesis process. After the viral RNA is released from the protein coat, the RNA will stimulate the formation of RNA polymerase enzymes, RNA synthesis or RNA replication - these enzymes are based on the presence of viral RNA which functions as a model and the presence of new RNA nucleotides. This RNA is not viral RNA but a complementary strand (mirror) of viral RNA which is formed by attaching to the original viral RNA, forming ds RNA. The two parts of this double strand immediately separate and this new RNA becomes the pattern for RNA synthesis - After the new nucleic acid is formed, the acid The viral nucleic acid will stimulate the host cell to produce protein molecules for the protein subunits that make up the protein coat of the virus. Factors Influencing Viral Diseases The emergence of viral diseases is influenced by host plant factors, viruses and the environment. Viral diseases occur if the attacking virus strain is virulent, the attacked plant is susceptible, and the current environmental conditions support the development of the disease. Host Plants Plant age and genotype influence viral infections and diseases. In systemic infections, plant age influences the spread of the virus in the host plant. The older the plant is when it continues to be infected, the more limited the spread of the virus in the plant. The results of the research showed that when old tomato plants were inoculated with TMV on young leaves, TMV would only spread to the top leaves of the plant, while the older leaves at the bottom did not experience infection.