GrainCorp Ltd. CEO Alison Watkins has resigned after an A$2.2 billion takeover bid by Archer Daniels Midland Co. (ADM) was blocked by Australia.

GrainCorp is seeking candidates to replace Watkins; in the meantime, Chairman Don Taylor will become temporary executive chairman. Watkins will join Coca-Cola Amatil Ltd. in March as the company's group managing director.

Australia Treasurer Joe Hockey blocked the takeover by Decatur, Ill.-based ADM on national interest grounds. Buying GrainCorp, the only major publicly traded grain merchant left in Australia after the country deregulated its wheat-export system, would have given ADM control of 280 storage sites and seven of the 10 ports that ship grain in bulk from the nation's east coast.

The decision to block the takeover is the first time a U.S. company has been blocked from buying Australian assets by the treasurer. ADM had agreed to buy GrainCorp for A$12.20 per share in April. ADM had planned to invest as much as A$250 million in GrainCorp, focused mainly on improvements to its rail infrastructure. Without the takeover, GrainCorp will likely need to move at a slower pace, said Taylor. The company wants to improve infrastructure to boost earnings and tap rising demand in the Middle East, Asia and Africa.