Participation of γ-aminobutyric acid in cell signaling processes and plant adaptation to abiotic stressors

Adaptation of plants to stress factors occurs with the participation of stress phytohormones, signaling network and plant neurotransmitters. Among the latter, in particular, γ-aminobutyric acid (γ-aminobutyric acid – GABA) is a non-proteinogenic four-carbon amino acid found in many prokaryotic and eukaryotic organisms. Its functions in plants have been actively studied only in the past decade. During this period, a lot of information has been accumulated about the protective effect of exogenous GABA on plants of various taxonomic groups under the influence of stress factors of various nature. The first national review is devoted to the analysis and generalization of data on the mechanisms of stress-protective action of GABA in plants. The ways of synthesis and metabolism of GABA in plant cells and the mechanisms of activation of these processes under stressful conditions are described. It is noted that the main way of GABA formation in plants is decarboxylation of glutamate by means of glutamate decarboxy­lase. Possible mechanisms of GABA reception and signal transmission to the genetic apparatus are discussed. Special attention is paid to the analysis of new data on the role of calcium in the activation of GABA synthesis and the realization of its physiological effects. Possible mechanisms of GABA’s influence on the functioning of mitochondria, its role in maintaining redox homeostasis under stressful conditions are discussed. At the same time, data on the increase in the expression of genes encoding the catalytic subunit of NADPH oxidase under the influence of GABA are presented. Functional connections between GABA and nitric oxide as a signaling mediator are considered. The effect of exogenous GABA on the main protective reactions of plants is characte­rized: the state of the antioxidant system, the accumulation of multifunctional low-molecular protectors, the synthesis of dehydrins and chaperones. The data on the phenomeno­logy of the effects of GABA under the main abiotic stresses are presented: the effects of extreme temperatures, drought and salinity on plants. The prospects for the practical use of GABA as a compound that combines the functions of an energy metabolite and a signaling mediator are noted

Signaling and protection systems in the adaptation of plants to cold

Global climate change increases the urgency of the problem of plant resistance to stress temperatures. Due to temperature instability in winter, as well as the earlier onset of meteorological spring with frosts, the likelihood of lowtemperature damage to plants increases. Adaptive strategies of the different plant species have their own specific features. The review uses mainly the examples of cultivated plants to analyze the current understanding of the mechanisms of cold stress signal perception and transmission to genetic apparatus. Emphasis is placed on the participation of new signal mediators (gasotransmitters) – nitric oxide and hydrogen sulfide – in the formation of plant defense reactions under hypothermia. Data on the role of antioxidant and osmoprotective systems as well as specific proteins in plant adaptation to cold are summarized. The issues of functional interaction between the components of stress-protective systems during cold adaptation are discussed. The opportunities are outlined for the practical use of gasotransmitter donors as agents for plant priming in order to increase their resistance to hypothermia. The possibilities of using indicators of the state of stress-protective systems to search for donors of resistance are also critically analyzed