Monkeyflower (Mimulus) uncovers the evolutionary basis of the eukaryote telomere sequence variation

Area of Science:

• Evolutionary Biology
• Molecular Biology
• Genomics

Background:

• Telomeres protect chromosome ends but exhibit sequence variation across species, with unclear evolutionary drivers.
• Telomerase RNA (TR) is a core component of telomere maintenance and dictates telomere sequence in eukaryotes.

Purpose of the Study:

• To investigate the evolutionary mechanisms behind telomere sequence diversification in Mimulus.
• To examine the role of telomerase RNA (TR) duplications and sequence divergence in shaping telomere evolution.

Main Methods:

• Conducted de novo transcriptomics and genome analysis across 18 Mimulus species.
• Utilized Nanopore sequencing, fluorescence in situ hybridization, and Telomeric Repeat Amplification Protocol (TRAP) with Terminal Restriction Fragment (TRF) analysis.

Main Results:

• Discovered at least three distinct telomere sequences in Mimulus: (AAACCCT)n, (AAACCCG)n, and (AAACCG)n.
• Identified TR duplications in several species, with evidence of functional consequences, such as differential paralog activity in M. lewisii.
• Observed that TR paralog duplication and subsequent divergence, followed by potential loss, underlie the evolution of varied telomere sequences.

Conclusions:

• TR duplication and sequence divergence are key evolutionary processes driving telomere sequence variation in Mimulus.
• This mechanism provides a framework for understanding telomere sequence evolution in eukaryotes.