Core genome responses involved in acclimation to high temperature

Area of Science:

• Plant Biology
• Molecular Biology
• Genetics

Background:

• Plants possess remarkable acclimation abilities to environmental stresses like high temperatures.
• Acquired thermotolerance is a critical survival mechanism for plants facing heat stress.

Purpose of the Study:

• To identify molecular mechanisms underlying acquired thermotolerance in Arabidopsis thaliana.
• To compare the effectiveness of different heat acclimation strategies on plant survival and gene expression.

Main Methods:

• Arabidopsis thaliana were subjected to severe heat stress (45°C) with or without prior acclimation.
• Two distinct acclimation protocols were employed: gradual (22°C to 45°C over 6h) and step-wise (38°C then 22°C).
• Transcriptome profiling and phenotypic analysis of T-DNA insertion mutants were performed.

Main Results:

• Gradual heat acclimation resulted in significantly higher survival rates and more extensive transcriptomic changes than step-wise acclimation.
• Upregulated transcripts were associated with protein protection, translation, and oxidative stress mitigation.
• Downregulated transcripts were linked to programmed cell death, basic metabolism, and biotic stress responses.
• Proline accumulation, toxic at high temperatures, was reduced by both acclimation methods through different molecular pathways.
• Eight new genes, including cytosolic ascorbate peroxidase and transcription factors HsfA7a and NF-X1, were identified as important for heat acclimation.

Conclusions:

• The rate and method of heat acclimation significantly impact plant thermotolerance and molecular responses.
• Both increased expression of protective genes and decreased expression of detrimental processes contribute to heat acclimation.
• Identifying novel genes involved in heat acclimation provides new targets for improving crop resilience.