Filamentous ascomycetes form multicellular hyphal networks that are compartmentalized by septa. The septum has a pore allowing the flow of cytoplasm and organelles between the adjacent cells. This intercellular communication is a common system in multicellular organisms as seen in gap junctions of animal cells and plasmodesmata of plant cells. In the industrial filamentous fungus Aspergillus oryzae, we found that hyphal tips burst out the cytoplasmic constituents soon after flooding colonies grown on agar media with water (hypotonic shock). Woronin body, an organelle specifically found in filamentous ascomycetes, is known to plug the septal pore adjacent to the lysed cell to prevent the excessive cytoplasmic leakage. Analysis with A. oryzae Aohex1 gene encoding a major Woronin body protein revealed that Woronin bodies plug the septal pores adjacent to the burst apical cells upon hypotonic shock. Furthermore, we demonstrated that Woronin bodies differentiate from peroxisomes by employing the peroxisomal proliferation/division machinery. Recently, we found that AoSO protein accumulates at the septal pore under various stress conditions (low/high temperature, extreme acidic/alkaline pH, nitrogen/carbon starvation, pulse laser treatment). This gives a possibility that intercellular communication via the septal pore is controlled in response to environmental stresses.
JSM Mycotoxins 61 (2), 53-58, 2011
Japanese Society of Mycotoxicology