Tubulin post-translational modifications are conserved during land plant evolution

Area of Science:

• Plant Biology
• Cell Biology
• Evolutionary Biology

Background:

• Bryophytes represent the earliest land plants, potentially possessing cytoskeleton adaptations for terrestrial stress.
• Microtubule dynamics are linked to plant stress responses.
• Investigating tubulin post-translational modifications (PTMs) in early land plants like Physcomitrium patens is crucial for understanding stress adaptation.

Purpose of the Study:

• To confirm the occurrence of tubulin PTMs in the earliest land plant lineage.
• To evaluate the impact of environmental factors (light, hormones, temperature, Ca2+) on tubulin PTMs.
• To explore the role of tubulin PTMs in plant stress adaptation.

Main Methods:

• In silico analysis of tubulin PTM-related enzymes in mosses.
• Microscopy to detect modified tubulin proteins.
• Quantification of tyrosinated, acetylated, and polyglutamylated α-tubulin under stress conditions.
• Visualization of calcium dynamics using GCaMP6f in P. patens.

Main Results:

• Key enzymes for tubulin PTMs are conserved in mosses.
• Red and far-red light increase polyglutamylated tubulin in protonemal cells.
• Auxin and cytokinin differentially affect tyrosinated and polyglutamylated tubulin.
• Tubulin PTMs and intracellular Ca2+ flux respond to temperature, hormones, and exogenous Ca2+.

Conclusions:

• Tubulin PTMs are unequivocally present in early land plants and likely contribute to stress adaptation.
• Physcomitrium patens exhibits dynamic, differentially regulated tubulin PTMs in response to abiotic factors.
• Findings are relevant for understanding plant responses to global warming, temperature stress, and improving agricultural practices.