Editing Moss (section)

===DNA repair===
The moss ''[[Physcomitrium patens]]'' has been used as a [[model organism]] to study how plants [[DNA repair|repair]] damage to their DNA, especially the repair mechanism known as [[homologous recombination]]. If the plant cannot repair DNA damage, e.g., [[double-strand breaks]], in their [[somatic cell]]s, the cells can lose normal functions or die. If this occurs during [[meiosis]] (part of sexual reproduction), they could become infertile. The genome of ''P. patens'' has been sequenced, which has allowed several genes involved in DNA repair to be identified.<ref name="pmid18079367">{{cite journal |last1=Rensing |first1=S.A. |last2=Lang |first2=D |last3=Zimmer |first3=A.D. |last4=Terry |first4=A. |last5=Salamov |first5=A |last6=Shapiro |first6=H. |last7=Nishiyama |first7=T. |last8=Sakakibara  |first8=K. |display-authors=7 |title=The Physcomitrella genome reveals evolutionary insights into the conquest of land by plants |journal=Science |volume=319 |issue=5859 |pages=64–9 | date=January 2008 |pmid=18079367 |doi=10.1126/science.1150646 |url=http://pubman.mpdl.mpg.de/pubman/item/escidoc:1221568/component/escidoc:1221567/rensing_et_al_science_2008.pdf|hdl=11858/00-001M-0000-0012-3787-A |bibcode=2008Sci...319...64R |s2cid=11115152 |hdl-access=free }}</ref> ''P. patens'' mutants that are defective in key steps of homologous recombination have been used to work out how the repair mechanism functions in plants. For example, a study of ''P. patens'' mutants defective in ''Rp''RAD51, a gene that encodes a protein at the core of the recombinational repair reaction, indicated that homologous recombination is essential for repairing DNA double-strand breaks in this plant.<ref name="pmid17921313">{{cite journal |vauthors=Markmann-Mulisch U, Wendeler E, Zobell O, Schween G, Steinbiss HH, Reiss B |title=Differential requirements for RAD51 in Physcomitrella patens and Arabidopsis thaliana development and DNA damage repair |journal=Plant Cell |volume=19 |issue=10 |pages=3080–9 | date=October 2007 |pmid=17921313 |pmc=2174717 |doi=10.1105/tpc.107.054049 |bibcode=2007PlanC..19.3080M }}</ref> Similarly, studies of mutants defective in ''Ppmre11'' or ''Pprad50'' (that encode key proteins of the [[MRN complex]], the principal sensor of DNA double-strand breaks) showed that these genes are necessary for repair of DNA damage as well as for normal growth and development.<ref name="pmid22210882">{{cite journal |vauthors=Kamisugi Y, Schaefer DG, Kozak J, Charlot F, Vrielynck N, Holá M, Angelis KJ, Cuming AC, Nogué F |title=MRE11 and RAD50, but not NBS1, are essential for gene targeting in the moss Physcomitrella patens |journal=Nucleic Acids Res. |volume=40 |issue=8 |pages=3496–510 | date=April 2012 |pmid=22210882 |pmc=3333855 |doi=10.1093/nar/gkr1272 }}</ref>