Auxins: Biosynthesis, metabolism, and transport

Abstract

Indole-3-acetic acid (IAA) is the key plant hormone of the auxin class, which controls all processes of plant growth and development. Information on IAA biosynthesis, metabolism, and transport is of great importance for understanding nearly all morphogenetic processes in plant development. Nevertheless, our knowledge about the organization of this auxin machine, which is of significance to all plants, is by no means complete. At present, six independent pathways of IAA biosynthesis are known, each of which has its own regulation and genetic base. Auxin metabolism and active transport are no less intricate systems with internal and external regulation. A lot of genes that determine the behavior of the auxin machine are still unknown, but those revealed can be employed in genetic engineering to obtain new plant forms with improved properties. The review presents modern concepts of the biosynthesis, metabolism, and active transport of auxin with regard to the genes underlying these processes.