(A. Piñeyro-Nelson, J. van Heerwaarden) These authors contributed equally to this work.
Transgenes in Mexican maize: molecular evidence and methodological considerations for GMO detection in landrace populations
Article first published online: 18 DEC 2008
© 2008 The Authors. Journal compilation © 2008 Blackwell Publishing Ltd
Volume 18, Issue 4, pages 750–761, February 2009
How to Cite
PIÑEYRO-NELSON, A., VAN HEERWAARDEN, J., PERALES, H. R., SERRATOS-HERNÁNDEZ, J. A., RANGEL, A., HUFFORD, M. B., GEPTS, P., GARAY-ARROYO, A., RIVERA-BUSTAMANTE, R. and ÁLVAREZ-BUYLLA, E. R. (2009), Transgenes in Mexican maize: molecular evidence and methodological considerations for GMO detection in landrace populations. Molecular Ecology, 18: 750–761. doi: 10.1111/j.1365-294X.2008.03993.x
Re-use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2.5, which does not permit commercial exploitation.
- Issue published online: 28 JAN 2009
- Article first published online: 18 DEC 2008
- Received 22 July 2008; revision received 2 October 2008; accepted 6 October 2008
- centers of origin;
- transgene flow
A possible consequence of planting genetically modified organisms (GMOs) in centres of crop origin is unintended gene flow into traditional landraces. In 2001, a study reported the presence of the transgenic 35S promoter in maize landraces sampled in 2000 from the Sierra Juarez of Oaxaca, Mexico. Analysis of a large sample taken from the same region in 2003 and 2004 could not confirm the existence of transgenes, thereby casting doubt on the earlier results. These two studies were based on different sampling and analytical procedures and are thus hard to compare. Here, we present new molecular data for this region that confirm the presence of transgenes in three of 23 localities sampled in 2001. Transgene sequences were not detected in samples taken in 2002 from nine localities, while directed samples taken in 2004 from two of the positive 2001 localities were again found to contain transgenic sequences. These findings suggest the persistence or re-introduction of transgenes up until 2004 in this area. We address variability in recombinant sequence detection by analyzing the consistency of current molecular assays. We also present theoretical results on the limitations of estimating the probability of transgene detection in samples taken from landraces. The inclusion of a limited number of female gametes and, more importantly, aggregated transgene distributions may significantly lower detection probabilities. Our analytical and sampling considerations help explain discrepancies among different detection efforts, including the one presented here, and provide considerations for the establishment of monitoring protocols to detect the presence of transgenes among structured populations of landraces.