Module 8 - Genetic Resistance to Disease Flashcards
what is resistance
the ability of an organism to either completely or partially exclude or overcome the effects of a pathogen or other damaging factors
types of resistance in the host
- tolerance
-escape - non-host resistance
- systematic acquired resistance
resistance due to individual genes with either large or small effect
mechanisms of variability
mutation and recombination
mutation
an abrupt change in the DNA of an organism (hereditary)
recombination
fusion of haploid nuclei followed by meiosis resulting in crossing over
why are we losing genetic variation in crops
we are breeding for uniformity, producing a genetic bottleneck
3 strategies for conservation of diversity of plant genetic resources
- In situlon farm
- traditional gene banks
- Svalbard global seed vault
What is the Ressources Phytogenetiques du Canada
Seed bank in saskatoon that is trying to acquire, preserve, and evaluate the genetic diversity of crops and their wild relatives
Basically storing viable, diverse germplasm
conditions for working collection seed storage
4 C, 10-20%RH in paper envelopes
conditions for long-term seed storage
-18C, no humidity control, in sealed envelopes
pathogenic
the ability of a genus or species of a pathogen to cause disease
virulence
the ability of an individual entity to cause disease under defined conditions
race
a group of pathogens within a specific species that can infect a specific set of plant varieties
pathogenicity genes
those that are essential for causing disease. genes may include those for recognition of the host by the pathogen
what does disease development require
the presence in the pathogen 1 or more genes for pathogenicity and lacks the gene for avirulence against the particular host
avirulence gene
a gene that codes for a product in the pathogen
effectors/elicitors
molecules that are produced by a pathogen which induce a response by the host
resistance genes
a gene in the host that controls resistance/produces a produce (receptor) that recognizes the pathogen effector
no gene resistance =
susceptibility
susceptibility gene
a gene in the host that controls susceptibility
non-host resistance
if pathogen has no pathogenicity genes, then plant/organism is a non-host/immune
hypersensitive reaction
the expression of resistance of a host in response to attack by pathogen, often by death of invaded tissue
who suggested the gene for gene relationship
H. H. Flor
gene-for-gene theory
for every gene for resistance in the host, there is a corresponding gene for avirulence in the pathogen
