LAUSR

Plant adaptation to the unstable environment relies on their ability to sense their surroundings, to generate and transmit corresponding signals to different parts of the plant, which evoke changes necessary for optimizing growth and defense responses. Plants, like animals, contain a huge repertoire of intra- and inter-cellular signals including organic and inorganic molecules. The occurrence of neurotransmitter-like signaling molecules in plants has been an intriguing field of research. Among these neurotransmitters, gamma-aminobutyric acid (GABA) was discovered in plants over half a century ago and studies of its roles as a primary metabolite have been well documented, particularly in the context of stress responses. In contrast, only recently evidence of the potential mechanism by which GABA acts as a signaling molecule in plants was reported. However, in spite of this breakthrough, the roles of GABA as a signaling molecule in plants are yet to be established and several aspects underlying the complexity of the GABA signaling system remain obscure. This review aims to summarize the unsolved questions in GABA signaling in plants; it also suggests research directions and technologies that would facilitate their solutions.