Exam notes Flashcards
Plant Defense (structural)
pre existing structures
formed in response to pathogen invasion
cellular structures
cork layers
stop phy advance fungi,bac,virus,nematodes
stop nutrients going pathogen
stop toxin movement from pathogen
Abscission layers
middle lamella dissolves and dead area fall out
caused by fungi,bac,vir
shot hole sys
Tyloses
overgrowths of the protoplasts of adj living parenchymatous cells protrude into xylem vessels through pits
biochemical defense
pre existing bioch def
lack of essential factors
induced by attack pathogen
biochem induced by attacking pathogen
hypersensitive response
production of chem
induced antimicrobial chem
*phytoalexins
*fungitoxic phenolics
*phenol-oxidizing compounds
(peroxidase)
*enzymes (PR proteins,chitinase)
*inactivation of path enzyme
*release of fungitoic cyanides
*detoxification path toxins
*systemic acquired resistance
Phytoalexins
very specific chem R induced by elicitor produced by host
tulipalin against Fusarium
fungitoxic phenolics
polyphenoloxidase
peroxidase
phenol-oxidizing compounds
PR proteins
chitinase
enzymes
polygalacturonase inhibitor in orange rind
inactivation of pathogen enzymes
amygdalin in stone fruit
release of fungitoxic cyanides
Chitinase
breaks down cell wall
System acquired resistance
- induced chem or microorganisms
- signal transport through plant
- systemic activated resistance
host defense
resistance varieties are best means of crontrol
- least expensive
- most effective
- environmentally safe
Pathogens have genes encoding virulence factors
often specific for infection of a few plants
pathogenicity factors
necessary for a pathogen to cause disease on a certain species of host plant
virulence factors
necessary for or enhancing the ability of a pathogen to cause disease on a certain cultivar, variety, or ecotype of the host plant
avirulence factors
pathogen components used by the host plant to recognize the pathogen through resistance genes
Risistance genes confer resistance to a ________ of a pathogen
specific race
Virulent races of pathogens occur in response to plant resistance:
*genes already present in small number
*mutation
*recombination genetic material
most common non host plant resistance
immunity
True resistance
controlled genetically
(function differently)