40 Questions
Plant viruses are relatively complex genetic entities
False
Genetic resistance is not considered a cost-effective approach to protect crops from virus infection
False
Viral infections of plants can be effectively eliminated chemically
False
The use of genetic resistance is the most effective and economical way to control plant diseases
True
Viruses cause up to 57% of plant diseases and epidemics.
False
Viral diseases occur less frequently in perennial plants because systemic invasion is slower.
True
Globalization and the rapid growth of the human population do not contribute to the global intensification of viral diseases.
False
Introduced crops are many times infected with plant viruses that spread from natural plants.
True
Quarantine measures are not essential to prevent the entry of viral pathogens
False
CRISPR is divided into three classes
False
Up to 70% of crops are grown from seeds
False
Nanoparticles are not used in agriculture for disease detection and carriers of genetic materials
False
Viruses are only transmitted via horizontal transmission routes
False
Persistent viruses are restricted to the xylem, circulating in the vector's body
False
Non-persistent viruses have limited spread due to their long retention period in the vector
False
Insect-borne viruses are classified as persistent, semi-persistent, and non-persistent based on the time the vector remains virulent
True
Plant viruses can only spread short distances due to their confinement to the intracellular symplast.
False
Increasing temperatures associated with global warming have no impact on the survival and transmission rate of infected seeds.
False
Seed transmission via gamete infections requires invasion during gametogenesis after fertilization.
False
Parasitic plants like Cuscuta spp. acquire viruses from the xylem of the host.
False
Parasitoids promoted aphid dispersion at short term, which enhanced CMV spread.
True
A. colemani significantly limited the spread and incidence of the persistent virus CABYV at long term.
True
Insect-transmitted plant viruses are completely independent of the behavior and distribution patterns of their vectors.
False
The escape response of aphids might cause a potential risk for virus dispersal.
True
The impact of aphid parasitoids on the dispersal of plant viruses with different transmission modes is not discussed in the text.
False
Results suggested that parasitoids did not have any effect on aphid dispersion at short term.
False
Biological control (BC) is always an effective method for managing aphid populations and plant virus spread
False
Aphid vectors transmitting non-persistent viruses can lead to long-distance virus spread
False
The presence of natural enemies like parasitoids can never affect virus spread by aphids
False
Aphid-Virus-Plant interactions do not influence vector settlement, behavior, and performance
False
The Spatial Analysis by Distance IndicEs (SADIE) methodology is not useful for studying distribution patterns of major viral diseases affecting outdoor crops
False
Parasitoid-mediated effects do not play a role in the dissemination of plant viruses infecting Cucurbitaceae
False
Parasitoids successfully located a variable number of aphids in the virus-infected source plant and mummies could be observed 7 days after the release of parasitoids, whereas they could not be detected after 2 days, as mummies were not yet developed.
True
The number of nymphs increased considerably after 7 days in the virus-infected source plant assay
True
The population density of adult morphs and nymphs in the CMV-infected source plant was frequently higher in the control cages than in those containing the parasitoid A. colemani, and significant differences were found
False
There were significantly more apterae adults and nymphs in the test plants of control arenas after 7 days
True
The occupancy rates were consistent with aphid density in the peripheral test plants, with significantly fewer plants occupied by aphids in the control arenas than in the arenas with parasitoids after 2 days, but larger occupancy rate in the control after 7 days
True
The percentage of test plants occupied by one or more alate, apterae, or nymphs was significantly different in the control and A. colemani cages after 7 days in the CMV-infected source plant assay
True
The mean percentage of test plants occupied by one or more alate, apterae, or nymphs was consistent with aphid density in the peripheral test plants in the control and A. colemani cages after 2 days in the CMV-infected source plant assay
False
The number of aphids on the peripheral test plants in the arenas without A. colemani was consistently higher after 7 days compared to those with A. colemani
False
Study Notes
Plant Virus Transmission and Entry Mechanisms
- Seed transmission allows viruses to spread over long distances and represents an important source of primary inoculum for many vertically transmitted viruses.
- Seed-borne viruses can survive long periods of drought in the seed, facilitating the geographical expansion of plant viruses.
- Increasing temperatures associated with global warming increase the survival and transmission rate of infected seeds, leading to virus epidemics and food safety issues.
- Plant viruses use two mechanisms to reach the seed: direct invasion of embryonic tissues and infection of the egg or pollen.
- Unlike animal viruses, plant viruses are confined to the intracellular symplast and move between cells through plasmodesmata.
- Seed transmission via gamete infections requires invasion during gametogenesis prior to fertilization.
- Genetic viral determinants involved in seed transmission have been analyzed in several plant species, such as Glycine max and barley stripe mosaic virus.
- Viruses from various genera, such as Cheravirus, Nepovirus, and Tobravirus, are transmitted by nematodes, contact in the field, and through the soil without a vector.
- Parasitic plants like Cuscuta spp. transmit a large number of viruses using their variable organs (haustoria) and acquire viruses from the phloem of the host.
- Accumulation of the virus at high levels throughout the plant is necessary for its survival and transmission, requiring multiple compatible interactions between viral proteins and cellular factors.
- The virus enters plants through the epidermis and mesophyll, and subsequent movement from cell to cell and replication occur in newly infected cells.
- Virus transport in phloem tissues involves translocation from mesophyll cells to sieve elements, and viruses use existing plant transport pathways, including plasmodesmata and phloem vasculature, for intercellular and long-distance transport.
Aphid-Virus-Plant Interactions and Biological Control
- Aphids are important pests worldwide, transmitting almost half of the known plant viruses, approximately 275 virus species within 19 different virus genera.
- Plant viruses can be non-circulative (non-persistent or semipersistent) or circulative (persistent), with different retention periods and sites within the vector.
- Aphid vectors' long-distance movements can lead to virus spread, with transient vectors mainly transmitting non-persistent viruses and colonising vectors transmitting persistent viruses.
- The interaction between plant pathogens and vectors influences vector settlement, behavior, and performance, with some viruses enhancing vector attraction to infected hosts.
- Biological control (BC) is a key component of Integrated Pest Management (IPM) programs, but introducing natural enemies to control aphids can complicate disease incidence within plant populations.
- Studies have shown that predator activity can increase virus incidence, while parasitoid activity can enhance virus spread by aphids in certain cases.
- The presence of natural enemies can affect virus spread, with foraging habits and escape behaviors of aphids playing a role in vector dispersal.
- Alarm pheromones play a crucial role in aphid dispersion, and their presence can enhance virus spread due to the presence of aphid parasitoids.
- The distribution patterns of aphids and their natural enemies provide valuable information about interplant movement of different aphid morphs, impacting biological control efforts.
- The Spatial Analysis by Distance IndicEs (SADIE) methodology has proven to be a powerful tool for studying distribution patterns, including the spatial spread of major viral diseases affecting valuable outdoor crops.
- The present study aimed to investigate tritrophic interactions within a system involving the host plant Cucumis sativus L., the cotton aphid Aphis gossypii Glover, and the parasitoid wasp Aphidius colemani Viereck.
- Parasitoid-mediated effects on the dissemination of two major plant viruses infecting Cucurbitaceae, Cucumber mosaic virus (CMV) and Cucumber aphid-borne yellows virus (CABYV), were assessed.
Learn about the transmission of viruses through seeds and their long-term survival, which facilitates the spread of plant viruses over significant distances. Understand the impact of seed-borne viruses on the geographical range of plant viruses and how increasing temperatures due to global warming can affect their survival.
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