The United Nations has named Food and Agriculture Organization (FAO)\'s Assistant Director-General for Forestry Eduardo Rojas-Briales as the commissioner for preparations for the Expo 2015 in Milan, FAO said on Monday.\"Our challenge for Expo 2015 is to provoke thought and inspire action, as part of an ongoing process to create sustainable and secure food systems,\" said Rojas, who was appointed Commissioner-General by United Nations Secretary-General Ban Ki-moon.\"The UN will work with its partners and the Expo 2015 host country, Italy, to share what we\'ve learned in our efforts to improve lives. We hope to help governments, organizations, companies and families make more conscious and consistent decisions on food security, nutrition, sustainable development and other issues that are critical to our planet,\" Rojas added.The Expo 2015 has chosen its theme as \"Feeding the Planet, Energy for Life.\" intending to address the universal and complex theme of nutrition from an environmental, historical, cultural, anthropological, medical, technical, scientific and economic point of view.Participants will focus on issues like food security, women and nutrition, sustainable development, and climate change, which \"tie directly into work done by FAO and other UN system agencies\", FAO said.The FAO, in collaboration with the International Fund for Agricultural Development (IFAD), the World Food Programme (WFP), and Bioversity International, will lead the effort to showcase the activities and best practices of the United Nations in fields related to the themes of the Expo