Alternative to Tissue Culture
Some genetic engineers have bypassed the tissue culture process by producing chimeric plants with the transgene in the germline cells. This means that they introduced the new gene into some but not all of the cells in a young plant.
Some of the cells in the seedling that geneticists have transformed are those that divide and develop into the pollen or egg producing tissues in the plant (the germline). Sexual progeny from these chimeric plants will then inherit the new gene and have one copy of the transgene in every one of their cells.
This chimeric alfalfa plant has a natural mutation that prevents chlorophyl production in some of the cells in the leaves. (Image by P. Hain)
Another transformation method that could potentially bypass tissue culture is the transformation of pollen. In a species such as corn, the transformed pollen could be used in a cross with the hope that some of the progeny will inherit the transgene. Research on this method has produced limited results.
The most promising method for germline cell transformation is to transform germ cells that are within the developing flowers. This process works in the model plant arabidopsis simply by dipping the plant’s inflorescence in a solution of agrobacterium. The hope is to adopt this strategy to crop species.