ZURICH/LONDON (Reuters) – Agrochemicals firm Syngenta on Friday rejected a $45 billion takeover offer from Monsanto, saying the offer undervalued the Swiss firm and did not fully take into account regulatory risks. “The offer fundamentally undervalues Syngenta’s prospects and underestimates the significant execution risks, including regulatory and public scrutiny at multiple levels in many countries,” Syngenta said in a statement. Syngenta shares rose 17 percent to 390 Swiss francs by 0715 GMT on Friday after the bid approach was confirmed.