RecQ Helicases Function in Development, DNA Repair, and Gene Targeting in Physcomitrella patens

Area of Science:

• Molecular Biology
• Genetics
• Plant Science

Background:

• RecQ DNA helicases are essential genome surveillance proteins conserved across life.
• Mutations in human RecQ genes cause developmental disorders, highlighting their importance.
• Understanding plant RecQ functions is crucial for genome stability and repair mechanisms.

Purpose of the Study:

• To investigate the roles of RecQ DNA helicases in the model plant *Physcomitrella patens*.
• To elucidate the functions of *Physcomitrella patens* RecQ4 (PpRecQ4) and RecQ6 (PpRecQ6) in development and DNA repair.
• To compare RecQ gene evolution and function between plants and humans.

Main Methods:

• Phylogenetic analysis of *Physcomitrella patens* RecQ genes.
• Generation and analysis of reporter and deletion mutants in moss (*Physcomitrella patens*).
• Reciprocal cross-species and cross-kingdom functional studies.

Main Results:

• PpRecQ4 and PpRecQ6 are present in meristematic moss tissues with distinct expression patterns.
• Loss of PpRecQ4 leads to sterility, developmental abnormalities, increased DNA damage sensitivity, and enhanced gene targeting.
• PpRecQ6 does not significantly impact moss development or DNA repair but enhances gene targeting efficiency.

Conclusions:

• PpRecQ4 acts as a repressor of recombination and is essential for *Physcomitrella patens* development and genome integrity.
• PpRecQ6 functions as a potent enhancer of gene targeting in moss.
• These findings provide insights into the conserved and divergent roles of RecQ helicases in eukaryotes.