The term “auxin” is derived from the Greek word auxein which means “to increase.” Auxins constitute an important group of naturally occurring hormones which have been detected practically in all land plants and in several soil- or plant-associated microbes. Naturally occurring auxins include indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), phenyl acetic acid, and 4-chloroindole-3-acetic acid (4-Cl-IAA). Of all these, IAA is the most extensively studied auxin (Fig. 15.1). Chemically, a common feature of all these molecules exhibiting auxin activity is the presence of acidic side chain on the aromatic ring. All the above natural auxins, except for phenyl acetic acid, are also indole derivatives.
KeywordsAuxin Acid growth hypothesis Apical dominance IAA Phytotropins PIN proteins Xylogenesis
Suggested Further Readings
- Bishop G, Sakakibara H, Seo M, Yamaguchi S (2015) Biosynthesis of hormones. In: Buchanan BB, Gruissem W, Jones RL (eds) Biochemistry and molecular biology of plants. Wiley Blackwell, Chichester, pp 769–833Google Scholar
- Leyser O, Day S (2015) Signal transduction. In: Buchanan BB, Gruissem W, Jones RL (eds) Biochemistry and molecular biology of plants. Wiley Blackwell, Chichester, pp 834–871Google Scholar