Genetically modified sunflower release: Opportunities and risks

Abstract

Sunflower (Helianthus annuus L.) is a crop native to North America for which there are no genetically modified commercial varieties. Some of the transgenic traits incorporated in other crops have already been subjected to research and experimentation in sunflower. Several new traits have also been noted, with the most relevant of these being the aim to increase latex production. GM sunflower release would modify crop management through improved mineral nutrition, weed control, insect and disease resistance, and product quality. In this research, the traits investigated were reviewed and analyzed in connection with main crop constraints. These characters could potentially influence agro-ecosystem components and produce a significant environmental impact. In regions where sunflower coexists with wild relatives this situation could affect germplasm resources, with this being especially important at the centre of origin and where Helianthus populations established in Africa, Asia, and Europe.

Introduction

Sunflower is the fifth most important source of edible oil after soybean, rapeseed, cotton, and peanut. The total world production of 25.8 million tonnes of sunflower seed go almost exclusively to oil extraction, providing 8.2% of total world volume, estimated at around 107 million tonnes. The sunflower crop is important in several Eastern European countries and also in Argentina, which provides more than 10% of world production. Sunflower is considered good quality oil, but does not command the high prices of other edible oils, for which there is greater demand in the most select markets. The mean price of sunflower on the Rotterdam market over the last decade was US$ 663 per tonne, exceeding those of soybean, palm, and coconut oils (FAS, 2005).

Biotechnology can speed up plant breeding, with many of the techniques complementing rather than substituting conventional methods (FAO, 2005a) and some biotechnological products have had a strong impact upon production systems because they have also facilitated crop management. This has led to a major increase in the total area devoted to genetically modified (GM) maize, soybean, cotton, and rapeseed production, which now exceeds 90 million ha, most of which are distributed amongst the 14 countries in which these crops have been authorized (James, 2005).

GM soybean constitutes a particularly significant case. Since its release as a commercial crop in Argentina 10 years ago, there have been increases in acreage, yield, and total production of 12.5%, 10.6%, and 25%, respectively (SAGPyA, 2002). This trend is still continuing and may, at least in part, be associated with RR (Roundup Ready^®) soybean tolerance to glyphosate herbicide (Monsanto, 2002). This simplifies its cultivation under no-till systems immediately after wheat harvest, and greatly facilitates weed control. Moreover, it helps to reduce production costs, making the crop profitable in otherwise marginal areas of Paraguay, Brazil, and Bolivia. These facts help to explain the major increase in production observed in South America during the last 10 years (FAS, 2005). Sunflower and peanut are the only major vegetable oil yielding crops that have no GM varieties authorized for commercial use. This does not imply that versions of these products are not available through research; their use has been discouraged for other reasons. In the case of sunflower, the release of genetically modified organisms (GMO) must be carefully considered because of the agro-ecological implications of a possible transgene escape. This is an open-pollinated crop native to North America (Heiser et al., 1969, Harter et al., 2004) which has now wild relatives throughout the world's crop regions, Europe (Faure et al., 2002), Australia (Dry and Burdon, 1986), Africa (Quagliaro et al., 2001, Ribeiro et al., 2001), and Argentina (Poverene et al., 2002). Diffusion to these areas can be addressed to human activity. Crop-wild gene exchange allows transgene escape via gene flow in sunflowers (Whitton et al., 1997, Linder et al., 1998, Rieseberg et al., 1999, Burke et al., 2002). Transgenes from the crop could potentially disperse into wild or weedy populations enhancing their fitness and modifying their ecological interactions (Burke and Rieseberg, 2003, Snow et al., 2003). Conversely, wild or weedy sunflowers and volunteers can invade and interfere crop, and may modify traits, such as oil composition, via pollen flow (Faure et al., 2002, Bervillé et al., 2004). Furthermore, the impact of GMO release on edible oil marketing could be negative, because of the well known consumer resistance to GM products. So far, these circumstances have delayed the development of GM sunflower for commercial uses. The goal of this work was therefore to analyze the likely impact of the use of transgenic sunflower on agronomic crop management and to consider the possible consequences of authorization being granted for the commercialization of such products.