They include heads of state, corporate chieftains and Holly-wood stars, among them Martin Sheen and the late Marlon Brando.

• 如果你相信负责耕种这种作物的美国人，这一长条突兀的绿色作物，有潜力可以供应全世界粮食，提供汽车燃料，并减缓全球暖化。