A $400 million expansion announced by Monsanto in April is starting in earnest with a ceremonial groundbreaking at the Chesterfield research center site.
The agricultural products company says it expects to bring 675 new jobs to the region over the next three years.
Gov. Jay Nixon was scheduled to join Monsanto officials at the ceremony Tuesday, just as he did when the company first unveiled the project at an international biotechnology conference in Chicago.
The Missouri Department of Economic Development has said Monsanto can expect to receive more than $31 million in state tax incentives if it creates the expected number of new jobs.