Contributes to DNA double-strand break (DSB) repair via somatic homologous recombination. Functions downstream of ATM. Highly expressed in closed buds and open flowers. Expressed at low levels in roots, stems, cauline leaves and siliques. Expressed in the region of the shoot and floral meristems. Induced by mitomycin C, bleocin and gamma-irradiation. No visible phenotype under normal growth conditions, but mutant seedlings exhibit drastic reduction of somatic homologous recombination rate after treatment with bleocin or mitomycin C.