Browsing by Author "Coetzee, Kim"

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    Evaluation of the crossability between small grains
    (Stellenbosch : Stellenbosch University, 2011-12) Coetzee, Kim; Botes, Willem; Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics.
    ENGLISH ABSTRACT: The greatest concern associated with genetically engineered crops is the possibility of GM crops contaminating other non-GM crops as a result of cross-pollination. Pollen drift is the primary mechanism in which GM crops contaminate traditional crops. However, genes can only be transferred between species if a certain degree of crossability exists. The aim of this study was to determine the potential risks associated with the release of transgenic crops and how to minimize these risks. Therefore, in this study crossability between three small grains was evaluated as well as pollen mediated gene flow from blue aleurone wheat. The potential frequency of cross pollination as well as the distance at which gene flow takes place was determined. When crossing triticale and rye the outcrossing was low in both directions. When rye was used as the female the F1 hybrid emergence was equal to zero and when triticale was used as the female parent the F1 hybrids were sterile. Therefore the potential for gene flow between triticale and rye is highly unlikely. The crossability between triticale and wheat was higher when triticale was used as the male parent, however these crosses did not produce many viable hybrid plants. When wheat was used as the male parent the F1 hybrid emergence was much higher and the F1 generation produced viable seed. In crosses between wheat and rye, gene flow is only possible when wheat acts as the female parent. The F1 generation is also capable of producing seed. In the pollen dispersal study an average OC of 0.4% was observed. A maximum OC of 2.4% was observed at a distance of 2.5 meters from the pollinator. There were samples with outcrossing percentages of 1% and 1.3% at distances of 50 meters and 60 meters respectively. Therefore, results indicated that prevailing wind direction is not necessarily associated with higher OC rates. Therefore, to reduce gene flow as much as possible an isolating distance of at least 65m should be used.