Pollen-mediated gene flow and seed exchange in small-scale Zambian maize farming, implications for biosafety assessment.
Gene flow in agricultural crops is important for risk assessment of genetically modified (GM) crops, particularly in countries with a large informal agricultural sector of subsistence cultivation. We present a pollen flow model for maize (Zea mays), a major staple crop in Africa. We use spatial properties of fields (size, position) in three small-scale maize farming communities in Zambia and estimate rates of cross-fertilisation between fields sown with different maize varieties (e.g. conventional and transgene). As an additional factor contributing to gene flow, we present data on seed saving and sharing among farmers that live in the same communities. Our results show that: i) maize fields were small and located in immediate vicinity of neighboring fields; ii) a majority of farmers saved and shared seed; iii) modeled rates of pollen-mediated gene flow showed extensive mixing of germplasm between fields and farms and iv) as a result, segregation of GM and non-GM varieties is not likely to be an option in these systems. We conclude that the overall genetic composition of maize, in this and similar agricultural contexts, will be strongly influenced both by self-organised ecological factors (pollen flow), and by socially mediated intervention (seed recycling and sharing).
GenØk - Centre for Biosafety, Tromsø, Norway.
Thomas
T
Bøhn
School of Biological Sciences, University of Cape Coast, Ghana.
Denis W
DW
Aheto
National Institute for Scientific and Industrial Research, Zambia.
Felix S
FS
Mwangala
Swedish University of Agricultural Sciences, Sweden.
Klara
K
Fischer
GenØk - Centre for Biosafety, Tromsø, Norway.
Inger Louise
IL
Bones
National Institute for Scientific and Industrial Research, Zambia.
Christopher
C
Simoloka
National Institute for Scientific and Industrial Research, Zambia.
Ireen
I
Mbeule
University of Vechta, Germany.
Gunther
G
Schmidt
University of Vechta, Germany.|University of Bremen, Germany.
Broder
B
Breckling
D000069599:Crop Production; D051456:Gene Flow; D011058:Pollen / Q000502:physiology*; D054817:Pollination / Q000502:physiology*; D012639:Seeds / Q000235:genetics* / Q000254:growth & development; D015024:Zambia; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development
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