Fundamental and technological aspects of phytohormone production by microorganisms: Azospirillum sp. as a model of plant growth promoting rhizobacteria.

Abstract

This chapter concentrates information related to the biosynthesis, metabolism, regulation, physiological role and agronomical impact of phytohormones produced by microorganisms with an emphasis on the plant growth promoting rhizobacteria belonging to the Azospirillum genus, considered to be one of the most representative and worldwide studied bacterial genera during the last thirty years. This review contains exhaustive information about the phytohormones auxins, gibberellins, cytokinins, ethylene, abscisic acid and jasmonates, as well as the plant growth regulators polyamines and nitric oxide; biosinthetized or metabolized by Azospirillum sp. and other growth promoting rhizobacteria in chemically defined medium or plant interaction conditions.