Differential requirements for RAD51 in Physcomitrella patens and Arabidopsis thaliana development and DNA damage repair.

RAD51, the eukaryotic homolog of the bacterial RecA recombinase, plays a central role in homologous recombination (HR) in yeast and animals. Loss of RAD51 function causes lethality in vertebrates but not in other animals or in the flowering plant Arabidopsis thaliana, suggesting that RAD51 is vital for highly developed organisms but not for others. Here, we found that loss of RAD51 function in the moss Physcomitrella patens, a plant of less complexity, caused a significant vegetative phenotype, indicating an important function for RAD51 in this organism.

The organization of Physcomitrella patensRAD51 genes is unique among eukaryotic organisms.

Genetic recombination pathways and genes are well studied, but relatively little is known in plants, especially in lower plants. To study the recombination apparatus of a lower land plant, a recombination gene well characterized particularly in yeast, mouse, and man, the RAD51 gene, was isolated from the moss Physcomitrella patens and characterized. Two highly homologous RAD51 genes were found to be present.