There is no clear definition of first, second and third generation transgenic plants. Often, 'first generation' means genetically modified plants (GMPs) that are already approved for cultivation and placement on the market. The term 'second generation' describes GMPs at an advanced stage of development and close to being approved. Genetically modified plants of the third generation are those used in research or which are in the very early stages of development.
As an alternative to distinguishing between first, second and third generations, genetically modified organisms can also be distinguished in terms of whether they possess new input or output traits.
Input-traits are designed to boost or stabilise crop yield. Examples include herbicide resistance in a range of crops, insect resistance in maize and cotton, fungal resistance in potatoes, rapeseed and wheat, and virus resistance in sugar beet and potatoes. Output-traits (use traits) refer to all downstream factors such as streamlining of and cost-cutting in production, transportation and storage processes, optimisation of feed and of raw materials for industry and medicine, and traits that produce functional foods. Plants with new output traits include the anti-sense tomato with a longer shelf-life, rapeseed with higher lauric acid content, potatoes with a different starch composition, poplars with lower lignin content (designed to simplify production of wood-free paper) and the production of substances for use in pharmaceuticals (gene pharming). GMOs for use in the production of functional foods have yet to reach market maturity. Current research and development includes the creation of vitamin-enriched potatoes, rice containing beta-carotene (known as 'golden rice'), and apples and strawberries containing protein that acts as a prophylactic to reduce dental caries. These GMOs and others like them raise hopes that public acceptance of agro-genetic engineering can be increased because their altered use traits should mean tangible benefits for consumers.