Kathleen Merrigan, a professor who helped develop U.S. organic food labeling rules, has been chosen for the Agriculture Department's No. 2 job by President Barack Obama. Merrigan, tapped for deputy secretary of agriculture, was head of the USDA's Agricultural Marketing Service from 1999-2001 during the Clinton presidency and helped to develop the USDA's rules on what can be sold as organic food. As a Senate aide, she worked on the 1990 law that recognized organic farming.