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Project 8 - Determining factors in the morphogenetic change from polar to non-polar growth in Trichoderma atroviride

Prof. Dr. Alfredo Herrera-Estrella


Polar growth is affected by environmental factors during  sexual and asexual development in filamentous fungi. It has been shown  that light, nutrient depletion, and mycelial injury are determinant in  morphogenetic changes occurring during asexual development. We recently  identified large sets of genes in Trichoderma atroviride, which expression is switched on or off in response to environmental  cues such as blue-light and mycelial injury. We propose to study the  role of two types of genes (transcription factors and signalling  proteins) that are turned on by these stimuli, and may therefore play  important roles in determining the switch from polarized to  non-polarized growth. Our gene expression data suggest the involvement  of oxidative stress and the MAPK homologue of Hog-1 in the morphological  transition. Therefore, we will analyze the effect of oxidative stress  in the process, as well as that of Hog-1, a putative member of the  signalling cascade involved in the response to oxidative stress, a  transcription factors.



Microscopic analysis of mycelial injury induced conidiation. Colonies were observed by light microscopy using Nomarski (top panels) or bright field upon staining with cotton blue (bottom panels), and photographed 6h (left panels) or 36h (right panels) after injury. The top two panels show a diagram of the structures formed 6 and 36h after injury. The left panels show a thin hyphae (green arrow) coming out of the cell just behind the damaged one. The right panel shows the formation of mature conidiophores (red arrow).