Small RNAs for Crop Improvement: Applications and Considerations for Ecological Risk Assessments

Abstract

The world faces many challenges in the development of crop systems that produce more food, fiber, and biofuels while minimizing environmental impacts. Today, the central dogma of “one gene, one protein” has been supplanted by a realization that small RNA molecules have profound effects in plants and can be engineered to create novel crop traits. Crop improvement using small RNAs has potential in two broad areas: (1) modifying metabolic and biochemical pathways and (2) silencing genes in pest organisms to provide plant protection. In the USA, genetically engineered (GE) crops have been grown since 1992 with RNA-mediated virus resistance and a few other traits. At present, proof-of-concept experiments have demonstrated potential for insect resistance, nematode resistance, increased nutritional value, decreased human allergens, better postharvest quality, new flower colors, and other traits. As more RNA-mediated traits are invented, regulatory agencies are faced with the task of assessing the safety of these traits for humans and the environment. In general, it appears that current ecological risk assessment (ERA) frameworks will be suitable for RNA-mediated traits. However, there are some new challenges in predicting risks prior to experimental field trials or commercial crop production. Targeted research is needed to answer key questions regarding the following: (1) environmental persistence and abundance of artificial small RNAs, (2) off-target effects within GE crops, (3) negative effects on nontarget organisms, (4) effects of genetic mutations and polymorphisms in crops and other organisms, (5) uncertainty in risk analysis, and (6) technologies to rapidly identify and quantify GE crops and foods containing artificial small RNAs.