WASHINGTON (Reuters) – U.S. Trade Representative Katherine Tai raised concerns about the investment climate in Mexico, including Mexico’s energy policies that Washington says threaten U.S. investment, her office said on Thursday after a meeting with Mexican Economy Minister Tatiana Clouthier. “She (Tai) discussed Mexico’s treatment of U.S. investors impacting important manufacturing operations in the southeastern United States and the importance of sound and transparent regulatory practices, including a science- and risk-based regulatory approval process for agricultural biotechnology products…