BUENOS AIRES, Sept 10 (Reuters) - The head of Argentina

biotech firm Bioceres said on Tuesday it will take at

least two years for the firm to start marketing its genetically

modified wheat variety HB4 to buyers in the United States,

following a U.S. government approval.

Last month, the U.S. Department of Agriculture approved the

cultivation of HB4 wheat, which has higher resistance to

drought, following approvals from Argentina and Brazil.