Pollen control during transgenic hybrid maize development in Mexico

Pollen containment may be necessary to prevent the dissemination of novel g enes from transgenic crops into sexually compatible land races or wild rela tives in locations where these are grown or occur naturally in the same vic inity. Routine maize (Zea mays L.) breeding activities employ controlled po llinations and are sometimes done in areas where land races or wild relativ es are known to occur. The ability of researchers to control pollen movemen t and to thereby control the potential pow of novel genes from transgenic m aize to land races or wild relatives was investigated. Using white- and yel low-seeded inbreds, pollen control was measured in two mating designs. The ability to control pollen was assessed by observing seed color in pollinati ons on adjacent plantings intended to trap uncontrolled pollen. In one expe riment, the yellow-seeded maize contained a transgene. In this experiment c ontaminant 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 conduc ted with completely effective pollen containment if the transgenic line is detasseled and serves as the female for pollination with a nontransgenic ma le inbred. However, precautions in addition to those used in these experime nts 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.