Our lab studies signaling pathways in fungi. Spores of the maize pathogen Cochliobolus heterostrophus, the cause of Southern Corn Leaf Blight, germinate on the leaf surface, form small appressorium-like infection structures, followed by penetration and invasive growth. Conserved eukaryotic signaling pathways are required for infection and disease. We are studying the three MAP kinase genes characterized in the sequenced genome of this pathogen. Plant signals and stress factors coordinatately control gene expression. Images, Benjamin Horwitz and Sophie Lev.
Cochliobolus heterostrophus genome project:
Confocal imaging of a Gfp fusion to the coding sequence of redox-sensitive transcription factor ChAP1, an ortholog of yeast YAP1. Like YAP1, ChAP1 localizes to nuclei upon oxidation, but we have also found that plant phenolics (ferulic acid, for example, a phenolic that is abundant in maize) cause a stress-like relocalization of Gfp:ChAP1 as in this image of the fungus growing invasively among maize leaf mesophyll cells, whose chloroplasts are visible by their red autofluorescence. Image: Moti Ronen.
In a generally beneficial interaction with plant roots, Trichoderma virens colonizes the outer root layers. We are using transcriptomics, proteomics and construction of loss-of-function mutants to understand the molecular dialog between fungus and host root. This dialog results in colonization and in the induction of systemic resistance of the plant to pathogen infection. The T. virens genome has been sequenced and the genome project is an essential resource for our work:
Trichoderma hyphae colonizing a tomato root. Imaged by confocal microscopy following staining with fluorescent-labelled wheat germ agglutinin (WGA) and counterstaining with propidium iodide. Image: Ariella Alperovitch-Lavy