Rapeseed cytoplasm gives advantage in wild relatives and complicates genetically modified crop biocontainment.
Biocontainment methods for genetically modified crops closest to commercial reality (chloroplast transformation, male sterility) would be compromised (in absolute terms) by seed-mediated gene flow leading to chloroplast capture. Even in these circumstances, however, it can be argued that biocontainment still represses transgene movement, with the efficacy depending on the relative frequency of seed- and pollen-mediated gene flow. In this study, we screened for crop-specific chloroplast markers from rapeseed (Brassica napus) amongst sympatric and allopatric populations of wild B. oleracea in natural cliff-top populations and B. rapa in riverside and weedy populations. We found only modest crop chloroplast presence in wild B. oleracea and in weedy B. rapa, but a surprisingly high incidence in sympatric (but not in allopatric) riverside B. rapa populations. Chloroplast inheritance models indicate that elevated crop chloroplast acquisition is best explained if crop cytoplasm confers selective advantage in riverside B. rapa populations. Our results therefore imply that chloroplast transformation may slow transgene recruitment in two settings, but actually accelerate transgene spread in a third. This finding suggests that the appropriateness of chloroplast transformation for biocontainment policy depends on both context and geographical location.
Allainguillaume
J
J
School of Biological Sciences, The University of Reading, Reading, Berkshire RG6 6AS, UK.
Harwood
T
T
Centre for Environmental Policy, Imperial College London, London SL5 7PY, UK.
Ford
C S
CS
School of Biological Sciences, The University of Reading, Reading, Berkshire RG6 6AS, UK.
Cuccato
G
G
School of Biological Sciences, The University of Reading, Reading, Berkshire RG6 6AS, UK.
Norris
C
C
National Institute of Agricultural Botany (NIAB), Cambridge, Cambridgeshire CB3 0LE, UK.
Allender
C J
CJ
Warwick HRI, Wellesbourne, Warwickshire CV35 9EF, UK.
Welters
R
R
Natural Environment Research Council, Swindon, Berkshire SN2 1EU, UK.
King
G J
GJ
Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
Wilkinson
M J
MJ
School of Biological Sciences, The University of Reading, Reading, Berkshire RG6 6AS, UK.|Present address: Institute of Biological, Environmental and Rural Sciences, Edward Llwyd Building, Aberystwyth University, Aberystwyth SY23 3DA, UK.
D001937:Brassica / Q000235:genetics*; D029741:Brassica rapa / Q000235:genetics; D002736:Chloroplasts / Q000235:genetics*; D018556:Crops, Agricultural / Q000235:genetics*; D051456:Gene Flow; D017343:Genes, Plant; D005819:Genetic Markers; D030821:Plants, Genetically Modified; D012639:Seeds / Q000235:genetics; D019076:Transgenes
D005819:Genetic Markers