Plant Defense Flashcards
Passive defense
Defense before infection to prevent pathogen entry and spread
Eg physical and chemical barrier
Physical defense
Cellulose cell wall=Physical barrier
Lignin= waterproof and indigestible
Waxy cuticle=prev collection of water on cell surface so absence of water passive defense
Bark= contains chem defense
Stomatal closure= when pathogen detected > guard close stomata
Callose
Large polys deposited seive tubes end of growing season
Around sieve plates= blocks in ST = prev pathogen spreading
Plasmodesmata= limits spread of virus
Tylose
Balloon like swelling fills xylem v= blocks And prevents spread of pathogens through heartwood
Contains terpenes
Chemical defenses
pathogenic prop eg terpenoids, phenol,alkaloid Hyd enz
Requires a lot of energy so prod until infection detected
Active defenses
When pathogens attack, specific proteins and glycolipids detect
Fortifies defenses by increasing physical and prod defense chem
Active defenses include
CW thickened and strengthen w additional cellulose
Callose between CW and pm near pathogen= strengthen CW
Blocks plasmodesmata
Oxidative bursts damage invading cells
Terpenoids
Range of ess oils+ antibacterial and antifungal properties
Scents
Phenols
Ab and af prop + Bark inhibit insect attacking
Bund to salivary proteins eg trypsin and digestive enzymes chymotryp to deactivate
High amt tannin=don’t grow and die= prev transmission of pathogens
Alkaloids
N containing comp eg caffeine,nicotine, cocaine and morphin
Bitter taste= inhibit herbivores
Some Inhibit protein synthesis, and some activate enzymes
Reduce grazing=suffer less damage
Defensins
Small cysteine rich proteins w microbial activity
Inhibit ion transport channels by action on mol in pm of pathogens
Hydrolytic enzymes between spaces
Chitinase break chitin in fungal CW
Glucanase hydrolyse glycosidic bonds
Lysozyme degrade bacterial cw
Necrosis
Injury activates intracellular enzymes
Enz destroy damaged cells and brown spots on leaves or die
Kill cells around= limit pathogen access to nutrients= red transm
So deliberate cell suicide
Canker
Sunken necrotic lesion in woody tissue
Causes death of cambium tissue in bark
