In this review, we summarize the results of experiments that lead to altered levels of
phytohormones in transgenic plants to improve plant productivity. The available data
indicate that manipulating the level of phytohormones might also be a promising way to
enhance the environmental stress tolerance of crop plants. In the regulation of the level of
phytohormones, both biosynthesis and their catabolism pathways can be targeted for
engineering purposes. Moreover, the signaling pathways of phytohormones should …