Abstract
Small-scale subsistence farmers in South Africa have been introduced to genetically modified (GM) crops for more than a decade. Little is known about i) the extent of transgene introgression into locally recycled seed, ii) what short and long-term ecological and socioeconomic impacts such mixing of seeds might have, iii) how the farmers perceive GM crops, and iv) to what degree approval conditions are followed and controlled. This study conducted in the Eastern Cape, South Africa, aims primarily at addressing the first of these issues. We analysed for transgenes in 796 individual maize plants (leaves) and 20 seed batches collected in a village where GM insect resistant maize was previously promoted and grown as part of an governmental agricultural development program over a seven year period (2001–2008). Additionally, we surveyed the varieties of maize grown and the farmers’ practices of recycling and sharing of seed in the same community (26 farmers were interviewed). Recycling and sharing of seeds were common in the community and may contribute to spread and persistence of transgenes in maize on a local or regional level. By analysing DNA we found that the commonly used transgene promoter p35s occurred in one of the 796 leaf samples (0.0013%) and in five of the 20 seed samples (25%). Three of the 20 seed samples (15%) included herbicide tolerant maize (NK603) intentionally grown by the farmers from seed bought from local seed retailers or acquired through a currently running agricultural development program. The two remaining positive seed samples (10%) included genes for insect resistance (from MON810). In both cases the farmers were unaware of the transgenes present. In conclusion, we demonstrate that transgenes are mixed into seed storages of small-scale farming communities where recycling and sharing of seeds are common, i.e. spread beyond the control of the formal seed system.
Highlights
Maize is a highly diverse crop, and has over thousands of years been under human selection for adaptation to various environments and agricultural practices [1, 2]
This paper reports on i) the screening for transgenes in external fields, home gardens and local household seed holdings; and ii) the seed management practices of farmers, including sharing and recycling, in this small-scale farming system in Eastern Cape, South Africa, to address current knowledge gaps on potential mixing of transgenes into local seed stores
We find it likely that she either purchased non-genetically modified (GM) seeds that were contaminated with transgenes two years ago, or that her non-GM seeds had cross-hybridized with locally grown GM maize during the last two growing seasons
Summary
Maize is a highly diverse crop, and has over thousands of years been under human selection for adaptation to various environments and agricultural practices [1, 2]. By 2013 South Africa had 2.3 million hectares of GM crops under cultivation, of which the majority was maize (representing 78% of the GM crops under cultivation) [3] This included insect resistant and herbicide tolerant maize hybrids as well as stacked events where the mentioned traits have been combined in a single hybrid. In the attempts to increase the yield of this staple crop, and thereby improve food security, the South African government has funded several agricultural programs during the last decade. Some of these programs have introduced GM maize (both insect resistant and herbicide tolerant) to smallholders [4, 5]. International seed and agrochemical companies have been included in the design and implementation of these government programs, and they have arranged demonstration trials and farmer workshops where they have promoted GM maize to smallholders in the region [4,5,6]
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