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46 Cards in this Set

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What is a virus
A submicroscopic infectious entity that is comprised of a coat protein and a nucleic acid.
What was the very first virus ever discovered?
Tobacco Mosaic Virus (TMV)
What was the first observed virus symptoms?
"Breaking" or varigated tulips
Who was the first to discover you could transer viruses "mechanically"?
Meyer
Who was the first to inoculate a healthy plant with filtered sap of an infected plant (bacteria filtered out)?
Ivanowski
Who coined the term "virus" or "contagium vivum fluidum"?
Beijerinick
Majority of plant pathogenic viruses contain what type of nucleic acid?
positive sense single stranded Ribonucleic Acid or "+ssRNA"
What are the five steps to TMV replication?
1.) Virus enters plant via a wound (mechanical or biological)
2.) TMV virus uncoats, leaving "naked" +ssRNA\
3.)+ssRNA is translated by Ribosomes into protein (capsid proteins, movement proteins, and nucleic acid replication proteins)
4.)+ssRNA replication (virus protein + plant cell enzymes = replicase)
5.)New particle assembly
6.)Cell to Cell movement through plasmodesmata (enlarged to fit TMV by movement particles)
What is the scientific name of Tobacco Mosaic Virus?
Nicotina benthamiana
What are 8 ways viruses can move between plants?
1.) Vegetative
2.) Mechanical
3.) Seed
4.) Pollen
5.) Insect
6.) Mite
7.) Nematode
8.) Fungal
What is the most common and economically important transmission of viruses?
Insect transmission
What is the number 1 disease management strategy and give some examples.
Genetic Host Resistance
-Planting genetically resistant species, cultivars, or varieties
-Transgenic Plants expressing viral coat proteins or antisense RNA's
-Cross Protection (infection of plant with weaker strain of disease)
What are some problems with Cross Protection?
1.) Even the mildest strains can cause 5% to 10% disease
2.) Strain may mutate to create an even more severe strain
3.) may cause severe symptoms in related cultivar species
4.) Labor intensive
What is the number 2 disease management strategy and give some examples.
1.) Rogueing
2.) Good Sanitary Hygeine
3.) Plant Virus Free seed or vegetative species (Periodic indexing of mother plants and meristem tip culturing)
4.) Maintain virus free vegetative stocks (heat therpy, meristem tip or tissue culturing)
5.) Modifiend Plant and harvesting procedures (break virus cycle by rotating out susceptible crops)
6.) Control Vector population
What is the number 3 disease management strategy?
Chemical Applications
What is the number 4 disease management strategy?
Biological Control
What is the number 5 disease management strategy?
Quarentine
What is Persistant Transmission?
This is where the virus is taken up by the vector when it is feding on an infected source. The vrius is passed through the digestive system and into the hymolymph, and then back to the salivary glands. Once it is there, it begins to replicate. Now everytime the vector goes to feed on an uninfected plant, the saliva it elases to feed infects the plant. Since this occurs for the rest of the vector's life, it is persistant.
What is Non-Persistant Transmission?
This is where the virus is taken up into the stylet of the vector when it is testing its food source. the virus becomes trapped in the food canal of the vector. When the vecotr lands on another uninfected food source, it will insert its stylet into it testing it once again. Now the infected saliva is released infecting the new plant. However, this must all be done quick, because the virus cannot live within the stylet for long. Thus, this is non-persistant.
What is a latent organism?
An infected organism that is showing no symptoms.
What are the 6 steps to the disease life cycle?
1.) Survival
2.) Inoculation
3.) Penetration
4.) Establishment of Infection
5.) Growth and Reproduction
6.) Dissemination
How do bacteria reproduce?
Binary Fission
What are 7 common symptoms of disease?
1.) Abnormal coloration (chlorosis, necrosis, reddening, vascular discoloration)
2.) Wilting of host
3.) Death of host tissue
4.) Defoliation
5.) Outgrowths (hypertrophy and hyperplasia)
6.) Stunting
7.) Replacement of host tissue
What are 4 common signs of disease?
1.) Bacterial streams from infected tissue
2.) Fungal fruiting structures
3.) Fungal mycelium
4.) Bodies of nematodes
Who was the "Father of Botany"?
Theophrastus
Who was the "Father of Plant Pathology"?
Anton DeBary
Who was the Rust God, who protected people from rust?
Robigo
What are 3 enviromental factors that greatly influence plant health?
1.) Low temperatures
2.) Low Moisture
3.) Nutritional problems
What is plasmolysis?
Water moving from intracellular space to intercellular space, separating the cell membrane from the cell wall. This is caused by a higher solute concentration outside of the intracellular space.
What are the major nuturents required by plants?
Carbon, Hydrogen, Oxygen, Phosphorus, Potassium, Nitrogen, Sulfur, Calcium, Magnesium
What do defieciency symptoms for any plant depend upon?
1.) The function of the element
2.) The mobility of the element
What is a primary air pollutant?
A pollutant is that is toxic in the form that it is emitted.
What us a secondary air pollutant?
A pollutant that must undergo a chemical reaction in the atmosphere in order to become toxic.
What are the minor nutrients required by plants?
Iron, Molybdenum, Boron, Copper, Manganese, Zinc, Chlorine
What is a vector?
A disease carrying organism
What are the symptoms in nitrogen deficiency?
Plant is pale green, with lower leaves chloroctic and drying to light brown color. If in later stages of growth, the stalks will be short and slender.
What are the symptoms in phosphorus deficiency?
Plant is dark green, with some red and purple colors developing. If in later stages of growth, the stalks will be short and slender.
What are the symptoms in magnesium deficiency?
Mottled or chlorotic leaves. Reddening sometimes with dead spots. Tips and margins cupped up and stalks are slender.
What are the symptoms in potassium deficiency?
Spots of dead tissue small, usually at tips or between veins, more marked at the margins. Stalks are slender.
What are the deficiency symptims of zinc?
Generalized dead spots that enlarge quickly. Inbetween veins, but eventually involve seconday and even primary veins. Thick leaves and stalks with shortened internodes.
What are the deficiency symptoms of calcium?
Young leaves of teminal bud hooked at first, dying back eventually at tips and margins. Later growth is characterized by a cut out appearance at these points. Stalk finally dies at terminal bud.
What are the deficiency symptoms of boron?
Young leaves of terminal bud become light green at bases with final breakdown here. Later growth, leaves become twisted, and the stalk finally dies back at terminal bud.
What are the deficiency symptoms of copper?
Young leaves permanently wilted without spotting or chlorosis. Twigs or stalks just below tip and seedhead often unable to stand erect in later stages when shortage is acute.
What are the deficiency symptons of manganese?
Spots of dead tissue scattered over the leaf with the smallest veins remaining green, producing a checkered or reticulating effect.
What are the deficiency symptoms of sulfur?
Young leaves with veins and tissue between veins light green.
What are the deficiency symptoms of iron?
Young leaves chlorotic, principal veins typically green, stalks short and slender.