Document Detail


Indole-3-acetic acid (IAA) biosynthesis in the smut fungus Ustilago maydis and its relevance for increased IAA levels in infected tissue and host tumour formation.
MedLine Citation:
PMID:  18705875     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Infection of maize (Zea mays) plants with the smut fungus Ustilago maydis is characterized by excessive host tumour formation. U. maydis is able to produce indole-3-acetic acid (IAA) efficiently from tryptophan. To assess a possible connection to the induction of host tumours, we investigated the pathways leading to fungal IAA biosynthesis. Besides the previously identified iad1 gene, we identified a second indole-3-acetaldehyde dehydrogenase gene, iad2. Deltaiad1Deltaiad2 mutants were blocked in the conversion of both indole-3-acetaldehyde and tryptamine to IAA, although the reduction in IAA formation from tryptophan was not significantly different from Deltaiad1 mutants. To assess an influence of indole-3-pyruvic acid on IAA formation, we deleted the aromatic amino acid aminotransferase genes tam1 and tam2 in Deltaiad1Deltaiad2 mutants. This revealed a further reduction in IAA levels by five- and tenfold in mutant strains harbouring theDeltatam1 andDeltatam1Deltatam2 deletions, respectively. This illustrates that indole-3-pyruvic acid serves as an efficient precursor for IAA formation in U. maydis. Interestingly, the rise in host IAA levels upon U. maydis infection was significantly reduced in tissue infected with Deltaiad1Deltaiad2Deltatam1 orDeltaiad1Deltaiad2Deltatam1Deltatam2 mutants, whereas induction of tumours was not compromised. Together, these results indicate that fungal IAA production critically contributes to IAA levels in infected tissue, but this is apparently not important for triggering host tumour formation.
Authors:
Gavin Reineke; Bernadette Heinze; Jan Schirawski; Hermann Buettner; Regine Kahmann; Christoph W Basse
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular plant pathology     Volume:  9     ISSN:  1364-3703     ISO Abbreviation:  Mol. Plant Pathol.     Publication Date:  2008 May 
Date Detail:
Created Date:  2008-08-18     Completed Date:  2009-01-06     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100954969     Medline TA:  Mol Plant Pathol     Country:  England    
Other Details:
Languages:  eng     Pagination:  339-55     Citation Subset:  IM    
Affiliation:
Max-Planck-Institute for Terrestrial Microbiology, Department of Organismic Interactions, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany.
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MeSH Terms
Descriptor/Qualifier:
Genes, Fungal / genetics,  physiology
Host-Pathogen Interactions
Indoleacetic Acids / metabolism*
Indoles / metabolism
Mutation
Plant Tumors / microbiology*
Ustilago / metabolism,  physiology*
Chemical
Reg. No./Substance:
0/Indoleacetic Acids; 0/Indoles; 392-12-1/indol-3-yl pyruvic acid; 87-51-4/indoleacetic acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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