Biotic-abiotic interactions

Question 1

How might stresses be combined?​

Answer 1

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​

Positive interaction - hyperstimulation​
Additive​ or Synergistic​

Question 2

How might stresses combine?​

Answer 2

Negative (antagonistic) interaction​

Amelioration of response​
i.e. response to combinatorial stress is less than single stress​

Priming of response / resistance​
Facilitated by common pathways used by different stresses​

Question 3

Competing defense pathways interact to determine host response​

Answer 3

these may include
Plant hormones as Effectors target phytohormone signalling pathways.​

Question 4

ABA signalling in guard cells is complex​

Answer 4

Guard cells are an important model as they have functions in controlling (1) water loss through transpiration - so respond to abiotic stresses such as drought and high light and (2) a point of entry for pathogens (stomata).​

Question 5

Biotic and abiotic stresses use the same signalling pathways

Answer 5

which leads to interactions in combinatorial application of stress treatments​

Both priming and simultaneous effects have been shown.​
Effects can be positive or negative (i.e. can make plants more or less susceptible to pathogenic attack).​

ABA or DCMU application suppresses hrpA ROS burst​
Temperature determines pathogen response​

Question 6

Short cut to discovery!​ (BABA)

Answer 6

BABA is a small molecule known to prime plant immunity.​
It is known to be made by microbes​
2014 – plant receptor found!​
2016 – BABA found in plants​

Question 7

Verticillium and Arabidopsis​

Answer 7

In this example, infected individuals responded differently to abiotic stress​

Mechanism is very clear ​
Sequential treatments, priming of resistance to drought​
Timing is important​

Question 8

When and how to apply a stress?​

Answer 8

Priming, in the context of plant physiology and stress response, refers to a process by which a plant is pre-conditioned or prepared to respond more effectively and efficiently to subsequent stress or stimuli. It involves the activation of certain defense mechanisms or pathways within the plant in response to a prior exposure to a mild stressor. This priming process enhances the plant’s ability to mount a faster, stronger, or more targeted defense response when faced with a subsequent stress or pathogen attack.

Priming can manifest at various levels, including biochemical changes, alterations in gene expression patterns, and potentially even epigenetic modifications. These changes enable the plant to activate defense mechanisms more rapidly or robustly upon encountering a stressor, thereby improving its resilience and ability to withstand adverse environmental conditions or pathogen attacks.

Question 9

Circadian basis of pathogenesis in rice blast disease​

Answer 9

Very different disease outcomes depending on time of day (abiotic conditions) inoculations are performed (biotic conditions)​.
Around 30-40 % genes are circadian controlled​
Plants use (anticipate) abiotic environment to produce a daily cycle of priming of disease resistance​