Detailed, no nonsense lecture notes on the interactions of abiotic and biotic factors in pathogenic defence, which discusses with examples, the interaction of biotic and abiotic stimuli, considers experimental design in understanding interaction studies, and discusses the importance of ABA in cross...
Lecture 4 – interactions of abiotic and biotic factors in pathogenic defence
Objectives:
• Discuss, with examples, the interaction of biotic and abiotic stimuli
• Consider experimental design in understanding interaction studies
• Discuss the importance of ABA in cross-talk between abiotic and biotic
stresses – clear interaction between Aba and the environment
Why look at combinatorial stresses?
• Many studies rely on studying one variable at a time
Isolation of variables – reductionist approach
A very successful and strong approach
But…
Stresses rarely occur singly in natural systems – if it is warm, it may
also be dry. If it is warm and wet, there may be a higher likelihood of
fungal attack. In the environment, stresses are in combinations.
How do these pathogens work in these combinations?
• This should be represented in experimental design / considerations
Stresses can be combined: depends on your question – which is more
appropriate based on what you’re looking for? Howlong does it take for plants to
respond to salt or temperautre
• Sequentially
e.g. 3 h UV-B illumination prior to inoculation with a pathogen
• Concurrently
e.g. transfer to dark immediately on inoculation with a pathogen
How might stress combine?
• Positive interaction - hyperstimulation
Additive
Stress A increases gene X expression L fold
Stress B increases gene X expression M fold
Stresses A and B together increase gene X expression L+M
fold
• Synergistic
Stress A increases gene X expression L fold
Stress B increases gene X expression M fold
Stresses A and B together increase gene X expression >
L+M fold
, • Negative (antagonistic) interaction
• Amelioration of response
i.e. response to combinatorial stress is less than single
stress
Priming of response / resistance – second time might have a
lower upregulating of response due to priming of first
stress.
Facilitated by common pathways used by different stresses –
evidence of common pathways
JA connected with necrotrophy resistance and insect resistance. Big overlap
,
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