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The fungus Trichoderma atroviride is a member of the genus Trichoderma to which belong many species known for high cellulase production, formation of various antibiotics, plant biocontrol and antagonistic activities against other fungi. Deletion of T. atroviride glutamate decarboxylase gene gad caused minor defects in germination, hyphal branching, slower growth and disruption of conidiation pattern. GABA can be used by fungi as a secondary carbon source and as a primary nitrogen source. We analyzed the effect of different nutrient compositions and environmental conditions (light and temperature) on growth and development of T. atroviride in strains defective in the functional GAD. The gad mutants grown on NH4NO3 as a sole carbon source grew slower and formed conidiation bands closer to each other which was clearly demonstrated during their cultivation in race tubes. The gad mutants exhibited slightly lower apical extension growth rate at the room temperature but their apical extension rate dropped significantly at 30 °C. Higher temperature had also inhibitory effect on gad mutant conidiation, whereas 30 °C seems optimal temperature for the parental strain. The optimal temperature for gad mutant conidiation was lower than in F534, about 25 °C. |
