Gamma-aminobutyric acid modulates antioxidant and osmoprotective systems in seedlings of Triticum aestivum cultivars differing in drought tolerance

The stress-protective effects of plant neurotransmitters, including gamma-aminobutyric acid (GABA) have been intensively examined in recent years. However, studies on the GABA influence on stress protective systems in bread wheat cultivars with different drought adaptation strategies are still lacking. The aim of this work was to estimate the GABA effect on the state of antioxidant and osmoprotective systems in etiolated seedlings of two wheat cultivars differing significantly in drought tolerance, namely Doskonala (non-drought-resistant) and Tobak (drought-resistant) under model drought induced by PEG 6000. Two-day-old seedlings were transferred to 15% PEG 6000 and incubated for two days in the absence or presence of GABA. Treatment with 0.1 and 0.5 mM GABA significantly reduced the growth-inhibitory effect of PEG 6000 on the roots and shoots of both cultivars, but to a greater extent on those of non-resistant Doskonala. It was shown that GABA treatment reduced drought-induced accumulation of H2O2 and MDA, stabilized SOD and GPX activity, the level of sugars, anthocyanins and flavonoids in seedlings of both cultivars. Meanwhile GABA treatment enhanced the stress-induced increase in proline content in the Doskonala cultivar, but decreased it in the Tobak, completely prevented stress induced decrease in anthocyanins and flavonoids level in the Tobak and only partially in Doskonala cultivar. Thus, the stabilization of the stress-protective systems functioning in the wheat cultivars and variety-dependent differences in response to GABA were revealed. Keywords: anthocyanins, antioxidant system, drought resistance, gamma-aminobutyric acid, oxidative stress, proline, Triticum aestivum