Evolutionarily Distant Streptophyta Respond Differently to Genotoxic Stress

Area of Science:

• * Evolutionary biology
• * Molecular biology
• * Plant science

Background:

• * Algal research typically focuses on morphology and phenotype related to habitat adaptation.
• * Understanding lineage evolution requires studying responses to environmental stressors like genotoxic agents.
• * Filamentous streptophyte green algae (Klebsormidium, Zygnema) and the moss Physcomitrella patens are relevant models for plant evolution.

Purpose of the Study:

• * To characterize the DNA damage and repair responses of Klebsormidium, Zygnema, and Physcomitrella patens to genotoxic stress.
• * To investigate the evolution of genome integrity maintenance mechanisms in streptophyte lineages.
• * To compare the sensitivity and repair capabilities of these organisms when exposed to DNA-damaging agents.

Main Methods:

• * Exposure of Klebsormidium, Zygnema, and Physcomitrella patens to genotoxic agents: bleomycin (DNA double-strand breaks), methyl methanesulfonate (DNA single-strand breaks), and UV radiation (photodimers).
• * Measurement of DNA lesion induction and repair rates, particularly for DNA double-strand breaks.
• * Comparative analysis of sensitivity and genome integrity maintenance across the studied species.

Main Results:

• * Klebsormidium and Physcomitrella patens exhibited similar sensitivity to DNA lesions and comparable DNA double-strand break (DSB) repair rates.
• * Zygnema displayed reduced DNA damage and a higher rate of DSB repair compared to the other two species.
• * Despite fewer detected lesions and higher repair rates, Zygnema demonstrated greater sensitivity to genotoxic treatment than Klebsormidium and Physcomitrella patens.

Conclusions:

• * Significant differences exist in genome integrity maintenance strategies among streptophyte lineages, as exemplified by Zygnema's distinct response to genotoxic stress.
• * The study reveals varied adaptive mechanisms for dealing with DNA damage in green algae and early land plants.
• * Comparative analysis of DNA repair pathways provides insights into the evolutionary divergence of genome stability.