EG 7&8 Flashcards
what is SAR
systemic acquired resistance, resistance in the whole plant as opposed to the infection site, and developed as a result of a first infection as opposed to innate
(all leaves of a plant respond to an infection in one leaf)
SAR tobacco mosaic virus experiment
upper leaves inocculated with virus produced large lesions, whole plant was inocculated 7 days later and upper leaves that had been prior inocculated produced smaller lesions (some resistance)
what are the components of mobile SAR signal
mainly methyl salicylic acid, also azelaic acid and glycerol-3-phosphate
what is MeSA and its relation to SAR
-MeSA is the transport form of SA and is a mobile SAR signal
-following inocculation of tobacco plants with TMV it was seen that enzymes converting MeSA to SA were essential for SAR in systemic tissue, while enzymes converting SA to MeSA in inoculated tissue were important to trigger SAR in the systemic tissue
-MeSA could be transported through the phloem from the inoculated tissue to the systemic tissue
-presence of MeSA improves resistance of tobacco plants to TMV
testing of DIR1 protein as a mobile SAR signal
WT and DIR1 mutant leaves inocculated then another (systemic) leaf inoculated 2 days later and the disease symptoms compared
-the dir1 mutant showed a normal local response but no systemic response
-dir1 encodes for a lipid transfer protein such as glycerol-3-phosphate
how is SA signalling involved in SAR
MeSA levels increase in both infected and systemic leaves while systemic leaves also show an increase in SA levels triggering the SA signalling pathway and its respective response genes which are both important parts of SAR
why are plants more resistant after SAR
-SA activates PR genes which encode for hydrolytic and cell wall modifying enzymes, antimicrobial peptides, components of signalling pathways
-this accumulation of PR proteins makes plants more resistant as well as allowing for quicker and stronger response to the next infection
what is transgenerational SAR
alarmed state induced by SAR can be transmitted to offspring leading to faster and stronger response to infection by the offspring
what is alliance number 1 between plants and insects
plant pollinator interactions where plants (angiosperms) rely on insects for successful reproduction through pollination
what are some threats to alliance number 1
-climate change (plants flower earlier when pollinators not yet active, quality of the nectar, changes activity period of pollinators, source of stress and infection for pollinators)
-pesticides (affect the health of pollinators, causes decline in pollinator populations)
what is alliance number 2 between plants and insects
predatory or parasitic insects protect plants from damage from herbivorous insects by attacking the herbivorous insects ie. biological pest control - introduction of ladybirds to help with an aphid problem
what is the insect life cycle
eggs, larvae/nymphs, pupae, adult
how do plants detect insects
through signal molecules (HAMPs and DAMPs) recognised by PRRs
what are HAMPs and an example
-herbivore-associated molecular pattern
-molecular motifs present in herbivores but foreign to plants
-recognised by PRR and BAK1 used to signal
-eg. volicitin from Spodoptera exigua
what are DAMPs and an example
-damage-associated molecular pattern
-molecular motif arising following mechanical damage by herbivore to a plant protein
-recognised by PRR and BAK1 used to signal
-eg. systemin, peptide generated from pro-systemin cleavage following wounding
