The plant hormone (phytohormone), auxin plays a crucial role in a wide variety of growth and developmental processes involving cell elongation, division and differentiation. The cellular responses to auxin involve not only electrophysiological changes at the plasma membrane, but also fast alterations of gene expression. Currently, the involvement of auxin in the regulation of gene expression is well-recognized. Using differential screening approaches, a number of auxin-regulated genes have been identified, mainly in elongating tissues and dividing cells.

Auxin plant hormones regulate a number of different processes involved in the growth and development of plants. In response to auxin are rapid changes occurring at the level of the cell membrane and changes in gene expression . Understanding the molecular principles of operation of auxin is essential to identify the hormone receptor . The variety of physiological processes regulated by auxin indicates the possibility of the operation of several independent mechanisms of auxin perception .

Plant hormones are important in all aspects of plant growth and development , but the phenomenon of hormonal homeostasis is not fully understood. Conjugation of phytohormones is considered an important element of the mechanism responsible for the levels of these compounds in the cell. It is a process that occurs in all tested plants in response to environmental and physiological factors .

Abscisic acid (ABA) is involved in many developmental processes and the plant life cycle in their adaptation to environmental stress conditions . An excellent model system for the study of perception and signal transduction of ABA are stomatal cells . Stomatal cell responses to ABA suggests that ABA perception may occur both in plazmolemie , as well as the cytoplasm , however, the receptor proteins have not previously been known. In recent years there has been considerable progress in identifying components of ABA signaling pathways .

Receptory etylenu, cytokinin i brasinosteroidów transmembranowymi kinazami białkowymi?