ABSTRACT
Analysis of transgenic plants with altered cytokinin synthesis has provided some interesting and unexpected insights into cytokinin biology. Transgenic plants offer an alternative that allows for reproducible hormone perturbations. Hormone levels can, in theory, be precisely manipulated both spatially and temporally. Many transcriptional promoters having various temporal and tissue-specific patterns of expression arc readily available, and construction of chimeric genes for plant expression is routine. The problem of “leaky” expression of promoters during regeneration has been a significant problem in producing plants with altered cytokinin balance. Transgenic plants were also shown to have a less-developed vascular system, exhibiting quantitatively less xylem. The addition of a gene that may interfere with normal regeneration further complicates the ability to obtain transgenic plants. Bombardment of intact tissues with a particle gun may circumvent much of the potential difficulty for some species such as soybean.
