VL 11: Stess memory

Question 1

What is decurrent/chronic stress and how to deal with it?

Answer 1

Recurrent/chronic stress: Continuous or repeated exposure to stress over an extended period.

Example in plants:
Abiotic Stress: Heat, drought, cold, and salinity.
Biotic Stress: Pathogen attacks, pest infestations.

Solution:
Priming Plants are primed by a moderate stress event. This leads to a different response after a recurrent stress following a stressfree lag phase. Priming has been found in response to different abiotic and biotic stresses.

Priming – described in response to different stresses. Lag phase that is stress free – differential response upon recurring stress – advantage in dealing with recurring stress – mechanisms are poorly understood

Question 2

Stress Memory

Answer 2

if the plant could remember that is was already very hot once and then be better prepared for the next hot spell.

Ability to “remember” past stress and respond better to future stress.

Heat stress memory or maintanance of acquired themotolerance is a model case for stress memory!

• Heat Shock Factor A2 (HSFA2) is a transcriptional activator

Question 3

Heat Stress in plants

Answer 3

Mechanisms:

• Epigenetic Modifications: Histone modifications, DNA methylation.
• Sustained Gene Induction: Memory genes like HSA32, HSFA2 is required for HS memory
• Chromatin State: Open chromatin, histone retention.
• Transcription Factors: HSFA2, HSFA3 is required for HS memory
• HSFA2 and HSFA3 together are required for sustained induction of memory genes
• Non-Coding RNAs: Regulation of stress-responsive genes.

Question 4

Second type of transcriptional memory

Answer 4

1. Active and separable from establishment
2. Requires specific proteins

Question 5

Summary

Answer 5

• HSFA2/3 control heat stress memory
• HSFA2/3 recruit sustained H3K4me3
• H3K4me3 marks the primed state
• Low histone turnover contributes to maintaining high H3K4me3
• CDK8 promotes PolII during transcriptional bursts