The U.S. Department of Agriculture (USDA) has agreed to join the American government panel that is reviewing state-owned ChemChina’s planned $43 billion acquisition of Swiss seeds and pesticide maker Syngenta, people familiar with the matter said Monday. The move will subject the deal to additional government scrutiny. It came after lawmakers wrote to Treasury Secretary Jacob Lew in March to ask that the USDA be involved in the review so that the potential impact of the transaction on domestic food security could be better assessed.