Ch 30: Plant Defense Flashcards
Biotrophic Pathogens
A plant pathogen that obtains resources from living cells.
Necrotrophic Pathogens
A plant pathogen that kills cells before drawing resources from them.
Host Plants
A plant species that can be infected by a given pathogen.
Virulent
Describes pathogens that are able to overcome a host’s defenses and lead to disease.
Avirulent
In plants, describes pathogens that damage only a small part of the plant because the host plant is able to contain the infection. In animals, describes nonpathogenic microorganisms.
R Proteins
Any one of a group of receptors in plant cells, each expressed by a different gene, that function as part of the plant’s immune system by each binding to a specific pathogen-derived protein.
R Genes
Any one of the group of genes that express the R proteins in plants.
Hypersensitive Response
A type of plant defense against infection in which uninfected cells surrounding the site of infection rapidly produce large numbers of reactive oxygen species, triggering cell wall reinforcement and causing the cells to die, thus creating a barrier of dead tissue.
Systemic Acquired Resistance
The ability of a plant to resist future infections, occurring in response to a wide range of pathogens.
Small Interfering RNA (siRNA)
A type of small double-stranded regulatory RNA that becomes part of a complex able to cleave and destroy single-stranded RNA with a complementary sequence.
Ti Plasmid
A small circular DNA molecule in virulent strains of R. radiobacter containing genes that can be integrated into the host cell’s genome, as well as the genes needed to make this transfer.
Latex
A white sticky liquid produced in some plants.
Alkaloids
Any one of a group of nitrogen-bearing compounds that can affect the nervous system of animals, produced by some plants as a defense against herbivores.
Terpenes
Any one of a group of compounds that do not contain nitrogen and are produced by some plants as a defensive mechanism.
Phenols
Any one of a class of chemical compounds, produced by some plants as a defensive mechanism.
Tannin
Any one of a group of phenols found widely in plant tissues that bind with proteins and reduce their digestibility.
Protease Inhibitors
Any one of a group of phenols found widely in plant tissues that bind with proteins and reduce their digestibility.
Trade-off
An exchange in which something is gained at the expense of something lost.
Plants are able to defend themselves against viruses that have invaded their cells by:
recognizing viral RNA and interrupting its replication.
Some herbivores are known as _____, feeding on a wide variety of plant species.
generalists
Alkaloids such as nicotine are relatively _____ for plants to produce because _____.
expensive; alkaloids contain high levels of nitrogen, which is often a growth limiting nutrient
Density-dependent mortality describes a situation in which seedlings:
of common species are more likely to be infected by pathogens.
In specific resistance, if a plant does not have an appropriate R protein, what will happen when it comes into contact with a pathogen?
The AVR protein will block the plant’s basal resistance, allowing the pathogen to infect the cell.
The hard-mineral silica plates found in some grasses is an effective defense because silica:
is abrasive and wears down insect mouth parts, so insects feed less efficiently and more slowly.
The presence of thorns is an example of _____ defenses.
constitutive
Insects consume approximately _____ percent of all plant production each year.
20
A tobacco farmer is walking through her fields. On a tobacco plant leaf, she notices several small brown spots surrounded by what appears to be necrotic or dying tissue. What kind of response is the plant demonstrating?
The plant is demonstrating a hypersensitive response.
One of the first chemotherapy drugs, vincristine, was discovered in the Madagascar periwinkle and is a(n):
alkaloid
T/F: N. attenuata produces variable levels of nicotine in response to the level of herbivory on the plant.
True
A number of plants produce terpenes. Does the production of terpenes have an advantage over the production of alkaloids?
There is an advantage because terpenes do not require nitrogen for their production.
Nitrogen-bearing compounds that affect animal nervous systems and are often bitter tasting belong to which class of compounds?
Alkaloids
T/F: In some cases, plant investments in defense can limit growth more than pathogen or herbivore damage would.
True
T/F: Plants and animals use the same 20 amino acids to construct proteins, but some plants have additional amino acids.
True
