Telomere dynamics in the lower plant Physcomitrella patens.

Area of Science:

• Plant biology
• Molecular genetics
• Cell biology

Background:

• Key principles in plant telomere research were primarily derived from Arabidopsis thaliana.
• Universality of these principles across diverse plant species, including lower plants, remains underexplored.

Purpose of the Study:

• To investigate telomere maintenance and telomerase function in the lower plant Physcomitrella patens.
• To compare DNA double-strand break repair pathways in P. patens with those in Arabidopsis thaliana.

Main Methods:

• Characterization of the Physcomitrella patens telomerase reverse transcriptase subunit (PpTERT).
• Quantification of apical cells, telomere length, telomerase expression, and activity in P. patens protonema cultures.
• Analysis of telomere maintenance in P. patens mutants for double-strand break repair factors (mre11, rad50, nbs1, ku70, lig4).

Main Results:

• Telomere stability was observed in P. patens.
• Telomerase activity and expression were found to be proportional to the number of dividing apical cells.
• Mutants in non-homologous end joining (NHEJ) repair factors did not exhibit telomere phenotypes or altered DNA double-strand break repair kinetics.

Conclusions:

• Telomere maintenance mechanisms in P. patens are conserved with other plants.
• Physcomitrella patens exhibits a dominance of homologous recombination over NHEJ for DNA double-strand break repair, contrasting with Arabidopsis thaliana.
• These findings highlight evolutionary differences in DNA repair pathway dominance between lower and higher plants.