Questions and Answers
What characterizes systemic infection caused by viruses in plants?
What is the typical incubation period for viral infections in herbaceous plants?
Which type of mosaic manifestation is characterized by light areas mainly between the veins?
What influences the diagnostic signs of viral diseases in plants?
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What typically happens to a plant once it is infected by a virus?
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Which symptom is commonly associated with viral infections in plants?
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Which type of mosaic is characterized by bright yellow spots bounded by veins?
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What is the defining feature of general chlorosis in plants?
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Which type of chlorosis specifically involves the yellowing of leaf edges?
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What results from local necroses in a plant hypersensitive to a pathogen?
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What type of necrosis is characterized by the presence of dark brown arcs and bands on potato tubers?
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Which type of mosaic features longitudinal stripes or chains of small spots on cereals?
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What symptom is characterized by a significant change in leaf shape and a curling tendency in certain plant diseases?
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What condition is associated with the fall of flowers and seeds in plants?
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What indicates a severe affectation of a plant's vascular system?
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Which of the following is NOT a characteristic symptom of viral plant diseases?
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In which condition do generative organs exhibit excessive vegetative growth?
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What type of coloration in leaves is characterized by purple or red-violet hues?
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What symptom reflects a mismatch in the growth rate of different parts of a plant?
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Which of the following growth characteristics indicates general dwarfism in plants?
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Study Notes
Viral Diseases in Plants
- Viruses cause systemic infections in plants, moving from initial infection sites to other areas, often without impacting meristems.
- Viral presence typically lasts until the plant dies, with potential transmission to offspring through vegetative reproduction.
- Symptoms result from internal physiological and biochemical changes in host cells due to virus infection.
Diagnosis of Viral Infections
- Diagnostic signs vary widely based on host characteristics, virus strain virulence, infection duration, and environmental conditions.
- Incubation periods differ: usually a few days to weeks for herbaceous plants, over a year for woody plants.
Types of Viral Manifestations
Mosaics
- Characterized by uneven green coloration in leaves, with various patterns and color variations:
- Common Mosaic: Light green spots interspersed with dark green areas; example includes tobacco mosaic virus.
- Intervein Mosaic: Light areas primarily between leaf veins; observed in beets and clover.
- Yellow Mosaic: Bright yellow spots, often delineated by veins; includes aucuba mosaic on potatoes.
- Marble Mosaic: Light green or yellow arcs and stripes crossing leaf veins; seen in tobacco rattle virus.
- Ring Mosaic: Yellow rings or patterns, sometimes necrotic, affecting species like tobacco and tomatoes.
- Stripe Mosaic: Longitudinal stripes or light green/yellow chains on leaves; common in cereals.
Chlorosis
- Diffuse yellowing of leaf tissues presented in several forms:
- General Chlorosis: Uniform yellowing without distinct veins; seen in potato curling.
- Intervein Chlorosis: Yellowing between veins; observed in beets and raspberries.
- Marginal Chlorosis: Yellowing at leaf edges; noted in strawberries.
- Apex Chlorosis: Yellowing of upper leaves; exemplified by apple top chlorosis.
Necroses
- Tissue death often follows or develops independently:
- Local Necroses: Localized tissue death at infection sites, often prominent in hypersensitive plants.
- Systemic Necrosis: Brown or black spots/stripes appear on various plant parts; examples include red veins on tomatoes.
- Apex Necrosis: Die-off of shoots or buds; illustrated by potato yellow dwarf virus.
Special Forms of Necrosis
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Internal Necrosis: Unique types in potato tubers:
- Concentric Necrosis: Dark bands on tubers' sections linked to specific viruses.
- Spotted Necrosis: Scattered brown spots within the tuber pulp.
- Reticular Necrosis: Browning of vascular tissue in tubers.
Plant Organ Deformations
- Includes changes in leaf shape, uneven growth rates, and leaf curling caused by physiological disturbances:
- Form-Forming Disturbances: Changes in leaf lamina shape.
- Growth Rate Mismatch: Symptoms like wrinkling or curling leaves.
Growth Suppression and Other Manifestations
- Growth Suppression: Results in overall dwarfism and reduced internode lengths.
- Wilting: Severe vascular damage leads to wilting symptoms in various plant types.
- Overgrowth: Excessive vegetative growth seen in reproductive structures.
Tumors and Abortivity
- Neoplasms: Tumors or leaf deformations caused by specific viral infections.
- Abortivity: Failures in flower or fruit setting due to viral infections; includes seedlessness examples.
Other Symptoms
- Anthocyanosis: Discolored leaves and stems with purple to blue coloration.
- Variegation: Uneven petal coloring or partial discoloration noted in flowers like tulips.
Diagnosis and Symptom Tracking
- A single infected plant can exhibit multiple symptoms, necessitating careful observation throughout its vegetative growth period for accurate diagnosis.
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Description
Explore the impact of viruses on plant health in this quiz. Learn about systemic infection, the transmission of viruses, and their effects on various parts of the plant. Test your knowledge on how viral diseases manifest in plants and their implications.
