DES MOINES, Iowa — A federal appeals court has given agricultural chemical-maker Syngenta Seeds hope that it may be able to proceed with a lawsuit against grain storage and transportation company Bunge North America for refusing to accept one of Syngenta’s genetically modified corn varieties. Syngenta sued Bunge in 2011, claiming it illegally refused to buy Syngenta’s Viptera corn from farmers that year. Viptera is genetically modified to control pests. The case highlights the complications arising …