Minn. Stat. § 508.54: MORTGAGE.

The owner of registered land may mortgage the same by deed or other instrument sufficient in law for that purpose and such mortgage or other instrument may be assigned, extended, discharged, or released, either in whole or in part, or otherwise dealt with by the mortgagee by any form of deed or instrument sufficient in law for the purpose. Such deed, mortgage, or other instrument, and all instruments assigning, extending, discharging, releasing, or otherwise dealing with the same, shall be registered and take effect upon the title only from the time of registration.