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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.
Mol Plant Pathol. 2008 May; 9(3):339-55.MP

Abstract

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+Show Affiliations

Max-Planck-Institute for Terrestrial Microbiology, Department of Organismic Interactions, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18705875

Citation

Reineke, Gavin, et al. "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." Molecular Plant Pathology, vol. 9, no. 3, 2008, pp. 339-55.
Reineke G, Heinze B, Schirawski J, et al. 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. Mol Plant Pathol. 2008;9(3):339-55.
Reineke, G., Heinze, B., Schirawski, J., Buettner, H., Kahmann, R., & Basse, C. W. (2008). 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. Molecular Plant Pathology, 9(3), 339-55. https://doi.org/10.1111/j.1364-3703.2008.00470.x
Reineke G, et al. 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. Mol Plant Pathol. 2008;9(3):339-55. PubMed PMID: 18705875.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - 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. AU - Reineke,Gavin, AU - Heinze,Bernadette, AU - Schirawski,Jan, AU - Buettner,Hermann, AU - Kahmann,Regine, AU - Basse,Christoph W, PY - 2008/8/19/pubmed PY - 2009/1/7/medline PY - 2008/8/19/entrez SP - 339 EP - 55 JF - Molecular plant pathology JO - Mol Plant Pathol VL - 9 IS - 3 N2 - 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. SN - 1364-3703 UR - https://www.unboundmedicine.com/medline/citation/18705875/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_ L2 - https://doi.org/10.1111/j.1364-3703.2008.00470.x DB - PRIME DP - Unbound Medicine ER -