Tenn. Code Ann. § 4-4-106

Except as may be provided in this chapter, such officers, assistants and employees as may be necessary to carry on the work of each department of the state government shall be appointed by the commissioner or administrative head of such department from the list of eligibles furnished by the department of human resources, and subject to such minimum qualifications as to efficiency, as may be established by executive order of the governor, or by law.