Pollen control during transgenic hybrid maize development in Mexico

Pollen containment may be necessary to prevent the dissemination of novel genes from transgenic crops into sexually compatible land races or wild relatives in locations where these are grown or occur naturally in the same vicinity. Routine maize (Zea mays L.) breeding activities employ controlled pollinations and are sometimes done in areas where land races or wild relatives are known to occur. The ability of researchers to control pollen movement and to thereby control the potential pow of novel genes from transgenic maize to land races or wild relatives was investigated. Using white- and yellow-seeded inbreds, pollen control was measured in two mating designs. The ability to control pollen was assessed by observing seed color in pollinations on adjacent plantings intended to trap uncontrolled pollen. In one experiment, the yellow-seeded maize contained a transgene. In this experiment contaminant seeds observed in the white maize were analyzed for the presence of recombinant DNA and the gene expression product. The results from these experiments indicated that routine plant breeding activities can be conducted with completely effective pollen containment if the transgenic line is detasseled and serves as the female for pollination with a nontransgenic male inbred. However, precautions in addition to those used in these experiments are necessary to provide complete control of pollen dissemination if a transgenic male is used to make crosses and approximate to 0.1% outcrossing to adjacent rows is deemed unacceptable.