Question

Why is it smart to transform genes from a liverwort to a moss (Physcomitrella patens) with homologous recombination?

Answer 1

Liverworts are considered to be a key group to understand the genetic basis of the critical innovations that allowed green plants to evolve from an aquatic ancestor and to adapt to the terrestrial environment.

Gene targeting mediated by homologous recombination is a powerful tool for functional analysis by reverse genetics. P. patens is the first moss to be successfully transformed from liverworts and has recently been singled-out as the first land-plant, and perhaps more interestingly the first multicellular eukaryote, in which gene targeting occurs with an highest efficiency.P. patens is one of a few known multicellular organisms with highly efficient homologous recombination meaning that an exogenous DNA sequence can be targeted to a specific genomic position to create knockout mosses. This approach is called reverse genetics and it is a powerful and sensitive tool to study the function of genes.The genome sequence of P. patens has revealed the presence of numerous genes that encode proteins necessary for repair of DNA damages by homologous recombination and by other pathways. Includes PpRAD51, a protein at the core of the homologous recombination repair reaction, is required to preserve genome integrity in P. patens. Loss of PpRAD51 causes marked hypersensitivity to the double-strand break-inducing agent bleomycin, indicating that homologous recombination needs repair reaction