| Abstract Detail
Molecular mechanisms of adaptation to host and environment Marroquin-Guzman, Margarita R. [1], Wilson, Richard [1]. GATA-dependent glutaminolysis drives appressorium formation by the blast fungus Magnaporthe oryzae. The GATA-family transcription factor ASD4 was previously shown to be required for appressoria formation and pathogenicity by the devastating rice blast fungus Magnaporthe oryzae. Using molecular genetics and biochemical approaches, we attempted to identify the underlying mechanisms governing ASD4-dependent regulation of appressorium formation, and how they might connect to other cellular signaling pathways. We found that Δasd4 mutant strains express a cryptic glutamine synthetase-encoding gene, GLN1, which is normally silent in wild type and results in elevated intracellular glutamine levels in Δasd4 mutants. Deleting GLN1 in Δasd4 restored intracellular glutamine levels and permitted appressoria formation. The TOR kinase pathway is activated in yeast in response to glutamine sufficiency signals, and we found appressorial development was restored in Δasd4 mutants by adding the specific TOR kinase inhibitor rapamycin. However, appressorium formation in Δasd4 mutant strains was not restored by treatment with monobutyryl cyclic AMP (cAMP), thus placing TOR downstream of the cAMP/cPKA signaling pathway during appressorium development. Together, these results suggest that the modulation of intracellular glutamine levels by ASD4 control of GLN1 expression impacts appressoria formation via the TOR signaling pathway. This is the first report indicating that TOR is a negative-acting regulator of appressoria formation in M. oryzae, thus adding to our knowledge about how these specialized infection cells develop.
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1 - University of Nebraska-Lincoln, Plant Pathology, 406I Plant Sciences Hall, East Campus, Lincoln, NE, 68583, USA
Keywords:
Magnaporthe oryzae
GATA factor
Nitrogen metabolism
Appressoria.
Presentation Type: Symposium or Colloquium Presentation
Session: SY5
Location: Room 103 AB/Kellogg Hotel and Conference Center
Date: Tuesday, June 10th, 2014
Time: 1:30 PM
Number: SY5002
Abstract ID:77
Candidate for Awards:None |
