Telomerase RNAs in land plants

Area of Science:

• Plant molecular biology
• Evolutionary genomics
• Telomere biology

Background:

• Telomeres protect chromosome ends, and their maintenance involves telomerase.
• Plant telomere repeat sequences and their associated RNA subunits (TRs) show significant diversity.
• Previous understanding of plant TRs was limited, particularly regarding their evolutionary conservation.

Purpose of the Study:

• To characterize telomerase RNA subunits (TRs) in Asparagales plants.
• To investigate the evolutionary history of TRs across land plants.
• To functionally validate identified TRs and reassess existing models of plant telomere maintenance.

Main Methods:

• Bioinformatic analysis of transcriptomic data from diverse plant species.
• Identification of orthologous TRs based on conserved sequence features and unusual telomere repeat lengths in Allium.
• Functional assays to test the telomeric templating activity of identified TRs.

Main Results:

• Identified and characterized TRs in Asparagales, including species with TTAGGG and TTTAGGG telomere repeats.
• Discovered a monophyletic origin of genuine TRs across land plants, challenging previous notions of high divergence.
• Functionally validated the identified TRs, demonstrating their templating role and refuting the function of a previously reported Arabidopsis TR.

Conclusions:

• The study reveals a conserved evolutionary history for plant TRs, suggesting a more unified model of telomere maintenance.
• The findings necessitate a revision of the current paradigm in plant telomere biology.
• The identified TRs provide a basis for predicting telomere sequences and identifying TRs in genomic data across land plants.