Plants as well as microorganisms, including bacteria and fungi, produce indole3acetic
acid (IAA). IAA is the most
common plant hormone of the auxin class and it regulates various aspects of plant growth and development. Thus,
research is underway globally to exploit the potential for developing IAAproducing
fungi for promoting plant
growth and protection for sustainable agriculture. Phylogenetic evidence suggests that IAA biosynthesis evolved
independently in bacteria, microalgae, fungi, and plants. Present studies show that IAA regulates the physiological
response and gene expression in these microorganisms. The convergent evolution of IAA production leads to the
hypothesis that natural selection might have favored IAA as a widespread physiological code in these
microorganisms and their interactions. We summarize recent studies of IAA biosynthetic pathways and discuss the
role of IAA in fungal ecology.
Keywords: biofertilizer, crosstalk, indole3acetic
acid (IAA), phytohormone