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41 Cards in this Set

  • Front
  • Back
What is a disease?
sub-optimal plant health brought about by a continuous irriation
What is an injury?
sub-optimal plant health brought about by n instantaneous event
What is a sign?
the actual pathogen
What is a symptom?
how a plant reacts to a pathogen
What is a pathogen?
a disease carrying organism
What is the most difficult challenge in diagnosing the cause of a symptamatic plant?
The answer is not what pathogen is causing the disorder, but whether the disorder is abiotic or biotic.
How can you confirm the cause of a disease caused by an abiotic agent?
Use a modified version of Koch's postualte:
1.) The abiotic agent must be found associated with the disease for all the diseased plants examined.
2.) The abotic agent must be applied to plants of the same species in the same or approximately the same strength or concentration as was found associated with the original conditions.
3.) The abiotic agent being tested MUST produce the similar symptoms on the test plants as originally observed on the symptomatic plants in question.
What is light quality and how does this differ from light quantity?
Light quantity would be the type of light received, whether it be the harsh bright light of a mid-day sun in July or a dull, yellow-tone light from a 60-watt bulb. Light quantity would be how much of the light would be received.
What response is exhibited by plants when placed in the dark?
Etiolation. Plants will have long, weak stems and fewer leaves, with those remaining leaves either being chlorotic. The height of the plant is also much taller, which is the way the plant tries to obtain more light.
Which wavelengths are utilized by plants to support photosynthesis?
380nm-495nm and 570nm-750 nm (everthing except "green" which is 495nm-570nm, this is why plants are green)
What are 3 physiological processes regulated by light quantity or quality?
Chlorophyll formation, photosynthesis, and plant respiration.
In what year and by whom was "local lesion reaction" first reported?
Francis Holmes in 1929
Why was the discovery of "local lesion response" so important?
First, it is a form of genetic host resistance, which means any plant exhibiting this reaction can be used as a resistant variety for crop plantings or used in breeding programs.

Second, the number of lesions on a leaf is directy proportional to the concentration of virus particles in the inoculum.

Third, since the symptoms develop rapidly and are usually distinct, plant exhibiting "llr" can be used as indicator plant for lab diagnosis or for virus indexing programs.
What did the TMV inoculum consist of in the TMV transmission experiemnt?
10 ml of phosphate buffer and 0.1g of celite and a small sample of infected leaf material
What are ELISA's?
Enzyme Linked Immunosorbent Assays
What are antibodies?
Proteins that are produced by the immune system of mammals with they are injected or challeneged with foreign entities (antigens)
What is the role of antibodies in the immune system?
To tag or mark antigens for destruction by white blood cells
How are ELISA's developed?
A specific pathogen is injected into an animal. this begins the production of antibodies specific to that antigen within the mammal. Once the antibodies are produced, they are harvested from the mammal by collecting a blood sample. the red blood cells are separated out leaving the rest of the blood components, which is called the antiserum. The antibodies are then isolated and then used to develop an ELISA for that pathogen.
What are the 5 steps to an ELISA?
1.) The pathogen specific antibodies are added to the wells of a plastic-titer plate. Antibodies like to stick to plastic, so they bind to the walls of the well. Rinse.
2.) Add skim milk, which consist of a cheap form of protein. Protein likes to stick to plastic as well, so this will fill in any gaps on the walls that the antibodies did not cover. Rinse.
3.) Take the sap from your infected plant and place it in the wells. If it is infected, then the pathogen in the sap will bind to the antibodies from step 1. Incubate and Rinse.
4.) A second pathogen specific antibody is added except this time it is linked or conjugated with an enzyme (often horseradish peroxidase). Incubate and Rinse. If the antigen from the previous step was present then the enzyme linked antibodies will bind to the antigens.
5.) A colorless substrate (usually hydrogen peroxide and a colorless indicator) is added to the well. If any of the enzyme linked detector antibodies from the previous step are present, the enzyme will catalyze a reaction turning the substrate from clear to green or orange. The darker the color, the greater the concentration of the pathogen.
How do viruses move cell to cell?
How do viruses move systematically through plants?
What is the 4 step process of Koch's Postulates?
1.) The microorganism in question must be present in every case of the disease.
2.) the microorganism must be isolated from the diseased host and gorwn in pure culture.
3.) The specific disease must be reproduced when a pure culture of the microorganism is inoculated into a healthy susceptible host.
4.) The microorganism must be recovered from the experimentally infected host.
What are the principles of aseptic technique?
1.) Know that contaminating organisms are present
2.) Kill them
3.) Keep them out
How is a culture media sterilized?
Heating it to 121 C for 15 minutes in an autoclave. Allow it to cool to 55 C before pouring it into a petri dish, where it will solidify at 42 C
What must all culture medias provide?
inorganic salts neccessary for life and a carbon source that provdies an energy source and organic molecules necessary for production of cell constituents.
What is a minimal medium?
A media composed of only the basic inorganic salt and carbon source
What is a complex media?
A step up from the minimal medium, adding vitamins, complex carbon sources, and unknown growth factors such as yeast exract or peptone.
In what concentration is agar usually added to a broth?
1.5-2.0% or 15-20g/l
What is selective media?
Media in which compounds or antibiotics are to a media to favor growth of certain organisms and not for others.
What is a differential medium?
A medium in which a certain organism needs to stand out, so certain dyes made added to stain the organism needed.
What agar was used in Lab 6?
Tryptic Soy Agar
What should you always clean your work area with?
70% ethanol, which is better than 95% ethanol which contains less water, which means it evaporates quicker
What are three things you should always remember when wanting to keep something sterile?
1.) Microorganism are ubiquitous
2.) Sterility must be achieved
3.) Sterility must be maintained
What is agar ?
a carbohydrate from marine algae. It is used because very few organisms eat it.
Where do most plant pathogenic bacteria multiply and move?
the Xylem
When you suspect a bacterial pathogen, what is the best diagnostic test to be used?
Observing bacterial streaming
What is the most important procedure used by plant pathologists for disease diagnosis and detailed studies of individual pathogens?
Isolation, the procedure of recovering or isolating a pathogen from its host
why is it difficult to do "isolation"?
Because of the presense of secondary invaders or other contaminent microorganism. These organims might outgrown the true problem, leading to confusion. to minimize this, the tissue collected is surface disinfected and good aseptic technique is used. Once the pathogen begins to grown, it is transferred to fresh culture media to attempt to end up with a pure culture.
How was the infected leaf tissue surface disinfected in lab 8?
a petri dish containing 10% bleach and 2 drops of Tween 20
What causes soft rot and how does it cause it?
Erwinia carotovora. the enzymes produced by the E. carotovora dissolve the middle lamella between the cells causing them to slide apart.
What method was used to disinfect the veggies in Lab 9?
First they were washed in Alconox (detergent), rinsed with 10% bleach, and then rinsed with distilled water.