Yoshioka Terutaka Kurei Shunsuke Osakabe Keishi et al. 2005 Apr. Plant Mol. Biol. 57(6):819-33. Shinozaki Kazuo Seki Motoaki Rad51 paralogs belong to the Rad52 epistasis group of proteins and are involved in homologous recombination (HR), especially the assembly and stabilization of Rad51, which is a homolog of RecA in eukaryotes. We previously cloned and characterized two RAD51 paralogous genes in Arabidopsis, named AtRAD51C and AtXRCC3, which are considered the counterparts of human RAD51C and XRCC3, respectively. Here we describe the identification of RAD51B homologue in Arabidopsis, AtRAD51B. We found a higher expression of AtRAD51B in flower buds and roots. Expression of AtRAD51B was induced by genotoxic stresses such as ionizing irradiation and treatment with a cross-linking reagent, cisplatin. Yeast two-hybrid analysis showed that AtRad51B interacted with AtRad51C. We also found and characterized T-DNA insertion mutant lines. The mutant lines were devoid of AtRAD51B expression, viable and fertile. The mutants were moderately sensitive to gamma-ray and hypersensitive to cisplatin. Our results suggest that AtRAD51B gene product is involved in the repair of double-strand DNA breaks (DSBs) via HR. 6 Kobayashi Masatomo Toki Seiichi Ichikawa Hiroaki Arabidopsis Rad51B is important for double-strand DNA breaks repair in somatic cells. Ito Yuji Abe Kiyomi 57 Yamanouchi Hiroaki Takyuu Toshio Kato Tomohiko Yoshioka Yasushi 2005 Apr Tabata Satoshi 819-33 15952068 Osakabe Keishi Machida Yasunori