Monsanto has made a $45 billion offer for the Swiss pesticide and seed company Syngenta -- an offer Syngenta has so far rejected.

The reasons for the rejection go beyond business as usual.

The first offer to create the world's largest seed and pesticide supplier came from Monsanto in May. Syngenta said it didn't want to take on antitrust concerns.

Syngenta has argued the offer is too low, but didn't resist the chance to take a jab at the GMO giant.

Syngenta said the proposal didn't take into consideration "the significant execution risks, including regulatory and public scrutiny at multiple levels in many countries."

Monsanto, on the other hand, has offered to sell Syngenta's seed operations, should the company accept its offer, in an effort to appease antitrust regulators.

It also claims it will shed some of its American-ness by changing the newly formed company's name and moving the headquarters to London.

Read More:

• Monsanto, Angling For Global Pesticide Dominance, Woos Syngenta (NPR)
• Syngenta Rejects Second Takeover Approach From Monsanto (New York Times)
• Syngenta Rejects Latest Monsanto Offer (Wall Street Journal)