Syngenta Biotechnology will invest $71 million constructing a new research complex at its Research Triangle Park campus.

The company, a division of Swiss agribusiness company Syngenta, chose RTP over sites in China, Singapore and Brazil. The expansion will add 15 employees to Syngenta’s existing RTP workforce of 400.

Officials announced the decision today during an industry symposium held at the N.C. Biotechnology Center in RTP.

Syngenta chose RTP because of North Carolina’s business climate and the support it received from local and state officials, said Michiel van Lookeren Campagne, the company’s president.

Last week, Durham County commissioners approved giving the company up to $225,000 in incentives to help win the expansion. The state provided no incentives, but Commerce Department officials were actively involved in recruiting the company.

Keith Crisco, the state’s commerce director, lobbied Syngenta executives in person during a trip to Basel, Switzerland last year.

The new facility will be a showcase for the state’s ag-biotech industry, Crisco said today.

Syngenta develops genetically engineered seeds and other products. The new 147,000-square-foot complex will include all-glass, climate-controlled greenhouses where scientists can adjust the environment under which those seeds grow.

The facility is being built on 50 acres adjacent to Syngenta’s main RTP site that the company purchased in 2009. Construction is expected to begin this summer, with completion expected by the middle of next year.

Syngenta is just the latest biotech company to announce expansion plans in the Triangle.

Biogen Idec expects to begin construction soon on a 180,000-square-foot building on its RTP campus.

The new space will give Biogen’s nearly 850 existing employees more room, allow the company to leave some leased offices and could lead to additional hiring.

Earlier this week, a California real-estate firm announced plans to build a $13.5 million agricultural-technology research center near RTP.

The 50,000-square-foot Alexandria Ag-Tech Center and greenhouse are scheduled to open next summer.