Influence of Field Size on Maize Gene Flow Using SSR Analysis

One of the factors that may affect the rate of cross-fertilization is the relative size of the pollen donor and receptor fields. To further investigate this matter, M. Palaudelmas from Genomica i Biotecnologia, IRTA, Spain together with other scientists designed a spatial distribution with four genetically modified (GM) varieties of yellow maize and formed different sized fields while maintaining a constant distance from field planted to non-GM white kernel maize.

They collected samples of cross-fertilized yellow kernels in white cobs at different distances in a transect traced in the dominant down-wind direction to identify the origin of the pollen through single sequence repeat (SSR) analysis. Based on the data that they collected, they validated a function that takes into account the gene flow present in the field border and that is helpful in estimating the percentage of GM that can be found in any area. It was also used to predict the total GM content of the field due to cross fertilization.

Results of the SSR analysis showed that while changes in the size of the donor field clearly influence the percentage of GMO detected, this effect is moderate. This study demonstrates that doubling the donor field size resulted in an approximate increase of GM content in the receptor field by 7%. This implies that differences in the size of the donor field have a less effect on GM content than variations in the size of the receptor field.

The abstract of the study is available at http://www.springerlink.com/content/e1201v05934p8313/.