Plant gene engineering has become a promising sector of biotechnology. Recently, genetically engineered tomato and pumpkin varieties have been put on the market in the US. Many other crops are undergoing field tests and will soon be commercially available. The development of pest-resistant varieties may provide a substantial contribution to a sustainable agriculture. Pest resistance and higher yield are important in the face of the growing world population. There are also major industrial applications, such as engineering a desired oil or starch composition and increasing the level of certain valuable secondary metabolites.