Glutamate decarboxylase (GAD) catalyzes glutamate decarboxylation to gamma8208;aminobutyrate (GABA) and is the first enzyme of the GABA shunt cycle. Endogenous changes in GABA levels in fungi correspond with developmental changes during conidiation and/or germination. It was observed previously that GAD activity in Trichoderma atroviride F8208;534 changes during conidiation, early germination and stationary phase of submerged culture. A lack of GAD activity during batch culture on sucrose as a sole carbon source lead to several aberrations in morphology and development: increased formation of chlamydospore8208;like structures, longer lag8208;phase, lower germination rate, higher number of bipolar germ tubes and increased hyphae branching. It has been demonstrated before that in vitro analysis of GAD activity in Trichoderma decreased in presence of cyclosporine A, a calcineurin signaling pathway inhibitor. Wild type strain in cultures containing various concentrations of cyclosporine A exhibited similar phenotypic characteristics of the delta gad strains - increased bipolar germination and hyphae branching. The similar effects of cyclosporine A have been known in other filamentous fungi (Neurospora, Aspergillus). Bipolar germination and branching of delta gad strains remained unaffected in the presence of cyclosporine A indicating that GAD could function as a downstream effector of calcineurin.
Full conference title:
11 th European Conference on Fungal Genetics
- ECFG 11th (2012)