Heat and chilling stress induce nucleolus morphological changes.

Area of Science:

• Plant Biology
• Cell Biology
• Stress Physiology

Background:

• The nucleolus is crucial for ribosome biogenesis in animals and involved in stress responses.
• The role of the plant nucleolus under environmental stresses like heat and chilling is largely unknown.
• Understanding plant nucleolus response to stress is vital for crop resilience.

Purpose of the Study:

• To investigate the role and morphology of the plant nucleolus under heat and chilling stress.
• To analyze the distribution of newly synthesized ribosomal RNAs (rRNAs) during stress conditions.

Main Methods:

• Used 5-ethynyl uridine (EU), an analog of uridine, to label newly synthesized rRNAs in Arabidopsis thaliana roots.
• Analyzed EU distribution within the nucleolus to assess rRNA synthesis, processing, and construction.
• Performed morphological analyses using whole rRNA staining and differential interference contrast microscopy.

Main Results:

• EU signals were strongly localized in the nucleolus, suggesting no compartmentalization of rRNA synthesis, processing, and construction in unstressed conditions.
• Under heat and chilling stress, EU incorporation was reduced in the nucleolus center.
• Heat stress induced speckled structures, while chilling stress resulted in round structures in the nucleolus center.

Conclusions:

• Environmental stresses like heat and chilling significantly impact plant nucleolus morphology and rRNA synthesis.
• These morphological changes suggest a disruption in ribosome biogenesis pathways under stress.
• The study provides new insights into plant stress response mechanisms at the nucleolar level.