German drug and crop chemical maker Bayer clinched a $66 billion takeover of U.S. seeds company Monsanto on Wednesday, ending months of wrangling with a third sweetened offer that marks the largest all-cash deal on record.

The $128-a-share deal, up from Bayer’s previous offer of $127.50 a share, has emerged as the signature deal in a consolidation race that has roiled the agribusiness sector in recent years, due to shifting weather patterns, intense competition in grain exports and a souring global farm economy.