Various mutants defective in phytohormone biosynthesis and signaling pathways have been identified and characterized recently. Functional analysis of corresponding genes has greatly enriched our knowledge of phytohormone biosynthesis, transport, and signal transduction. Moreover, identification of phytohormone receptors and dissection of cross-talks among phytohormones allow us to elucidate the molecular basis of actions of phytohormones. The recent comprehensive work on the regulation of the biosynthesis, transport and signaling of phytohormones will help us to understand phytohormone actions in plant growth and development and their potential application in crop improvement. In this review, we summarize the latest work about phytohormones actions and highlight some common issues in this field.
