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

2024
Views:

95

Pages:

1
Author:

Vernanda G.

Symptoms Caused by Plant Viruses Plants infected with viruses can cause various symptoms in some or all parts of the plant. The most common symptom is a decrease in the growth rate of the plant which causes stunting. Almost all viral diseases can cause a decrease in yield and shorten the life of the plant. The most obvious symptoms of virus-infected plants usually appear on the leaves, but some viruses can cause symptoms on stems, fruit and roots with or without symptoms on the leaves. Plant viruses do not have enzymes, toxins or other compounds like other pathogens, but viruses can cause damage to plants. Viral RNA is what causes disease, but large amounts of RNA do not necessarily cause disease symptoms.Some viruses can infect plants without causing visible symptoms, they are latent viruses and their hosts are symptomless carriers, some infected plants can show no symptoms under certain environmental conditions. If environmental conditions change, masked symptoms can arise. Viral infections affect cell metabolism and cause changes in cell biochemistry and physiology. These changes are external or macroscopic external symptoms. There are also changes that are internal or microscopic, internal symptoms. External Symptoms Symptoms of the disease that can be seen directly without the aid of a microscope, are caused by primary infection in the inoculated cells. Local symptoms, local symptoms can be distinguished from the surrounding tissue in the form of spots. 1. Local Symptoms Limited to the primary infection, known as local spotting symptoms, which can include chlorosis and necrosis. Symptoms of local spots on Chenopodium amaranticolor leaves by PStV. 2. Systemic Symptoms It is not limited to the primary infection, but spreads to other parts and causes secondary infections. a. Stunting: the size of plants infected with a virus is smaller than normal plants - can occur in all parts of the plant, leaves, flowers and fruit - for example: stunting in banana plants caused by Banana Bunchy Top Virus. b. Mosaic The presence of light green, yellow or white parts of the leaves interspersed with the normal green color of the leaves or fruit - the presence of white parts interspersed with the color of the flowers or fruit.Based on patterns or color changes, mosaics can be categorized into: • Mottling, streak, ring pattern, line pattern, vein clearing, vein banding, etc • Vein banding -> the green part is only around the leaf veins. Example: CVPD disease in oranges. • Vein clearing -> the yellow part is only around the leaf veins. Example: tirteza disease in oranges.