In a fight that highlights global sensitivity over genetically modified crops, Cargill Inc. sued Syngenta AG, claiming that the Swiss seed maker's push to sell bioengineered corn seeds that weren't approved in China cost the U.S. grain company $90 million when Beijing rejected corn shipments. The suit, filed on Friday in Louisiana state court, escalates tensions that have shaken U.S. agribusiness since China last year sharply curtailed imports of U.S. corn. Beijing's move all but closed off a major market for the grain.