3'-5' DNA helicase that may play a role in the repair of DNA (By similarity). Required to promote but not to suppress crossovers. ATP + H2O = ADP + H(+) + phosphate Mostly expressed in roots, seedlings, shoots, shoot apical mersitem, flowers, and siliques. Repressed by cold. Not mutagen-sensitive, and impaired in hyperrecombination (HR). Belongs to the helicase family. RecQ subfamily.