13. Trustee to protect title to trust- property.- A trustee is bound to maintain and defend all such suits, and (subject to the provisions of the instrument of trust) to take such other steps as, regard being had to the nature and amount or value of the trust- property, may be reasonably requisite for the preservation of the trust- property and the assertion or protection of the title thereto. Illustration The trust- property is immoveable property which has been given to the author of the trust by an unregistered instrument. Subject to the provisions of the Indian Registration Act, 1877 (3 of 1877 ), 1[ the trustee' s duty is to cause the instrument to be registered.