Ontology engineering

COMMENTARY© 2010 Nature America, Inc. All rights reserved.Coexistence practices in non-GMagricultureWhat often gets forgotten in the heat of theGM/non-GM coexistence debate is that differentvarieties of the same crop species havecoexisted for generations and that adventitiouspresence is recognized as an inevitableconsequence of coexistence that can be minimizedbut not entirely eliminated. Therefore,almost all traded agricultural commoditiesanticipate some degree of inadvertent mixing,and thresholds exist that are recognizedin laws, regulations and/or voluntarystandards.Such thresholds have resulted in thedevelopment of a series of measures that areapplied during cultivation, harvest, transportand storage to minimize outcrossing, thegrowth of volunteer plants and inadvertentmixing 3 . These best practices were establisheddecades ago and have evolved to deliver highpurity seed and grain to support the production,distribution and trade of products fromdifferent agricultural systems. The principlesof these coexistence practices are dependenton context (which crops and where they aregrown), consistent, proportionate to need,fair and practical. Examples of successfulcoexistence practices in non-GM agricultureinclude production systems for certified seeds(e.g., hybrid seed), organic crops coexistingwith conventional crops and commoditycrops coexisting with specialty crops (e.g.,field corn with sweet corn and/or popcorn,and specialty corns such as high-amylose,high-oil, white, waxy, hard endosperm andnutritionally dense varieties) 6 .Perhaps one of the best-studied examplesof coexistence in conventional agricultureis standard rapeseed varieties and specialtyhigh erucic acid rapeseed (HEAR) varietiesfor industrial use, particularly because HEARis regarded as antinutritional and undesirablein food (and therefore constitutes an actualrisk rather than a consumer preference, as isthe case for GM crops). Contracts for growingHEAR crops require that only certifiedHEAR seed is used, equipment should becleaned and segregated and that there shouldbe an isolation distance of between 50 m (e.g.,in the UK) and 100 m (e.g., in Germany)from other rapeseed crops. The admixturethreshold for HEAR in food rapeseed is 2%although recorded levels are usually muchlower. For example, the 100-m separation distancein Germany generally delivers seed lotswith HEAR levels 0.5%. In the UK, coexistenceresearch shows that separation distances aslow as 9 m still provide bulk rapeseed harvestscontaining