Aberrant Synthesis of Indole-3-Acetic Acid in Saccharomyces cerevisiae Triggers Morphogenic Transition, a Virulence Trait of Pathogenic Fungi

Department of Biology and Biotechnology, Life Sciences and Bioengineering Center at Gateway Park, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01605, USA.
Genetics (Impact Factor: 5.96). 03/2010; 185(1):211-20. DOI: 10.1534/genetics.109.112854
Source: PubMed


Many plant-associated microbes synthesize the auxin indole-3-acetic acid (IAA), and several IAA biosynthetic pathways have been identified in microbes and plants. Saccharomyces cerevisiae has previously been shown to respond to IAA by inducing pseudohyphal growth. We observed that IAA also induced hyphal growth in the human pathogen Candida albicans and thus may function as a secondary metabolite signal that regulates virulence traits such as hyphal transition in pathogenic fungi. Aldehyde dehydrogenase (Ald) is required for IAA synthesis from a tryptophan (Trp) precursor in Ustilago maydis. Mutant S. cerevisiae with deletions in two ALD genes are unable to convert radiolabeled Trp to IAA, yet produce IAA in the absence of exogenous Trp and at levels higher than wild type. These data suggest that yeast may have multiple pathways for IAA synthesis, one of which is not dependent on Trp.

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    • "avourable candidates for use as biofertilizers (Saharan & Nehra 2011). IAA-producing microorganisms are believed to enhance root growth and increase the root length, resulting in an increased root surface area, thus enabling increased access to soil-based nutrients. This phytohormone is commonly produced by PGPR (Vessey 2003;Yadav et al. 2010).Rao et al. (2010)suggested the presence of a Trpindependent pathway for IAA synthesis in baking yeast (Saccharomyces cerevisiae). To determine whether a Trpindependent pathway is a common to yeasts, we analysed IAA production in yeast cultures without Trp. The yeast isolates in our study produced IAA in the absence of exogenous Trp. Two isolates produced"
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    • "Our results are in agreement with other studies. The accumulation of IAA by Saccharomyces cerevisiae reached its highest level after cultures entered stationary phase (Rao et al. 2010). It was shown that endophytic yeasts genus Rhodotorula produced maximum IAA at 7 d (Xin et al. 2009). "
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