Abstract
γ-Aminobutyric acid is a non-protein amino acid involved in various metabolic processes. The objectives of this study were to examine whether increased GABA could improve heat tolerance in cool-season creeping bentgrass through physiological analysis, and to determine major metabolic pathways regulated by GABA through metabolic profiling. Plants were pretreated with 0.5 mM GABA or water before exposed to non-stressed condition (21/19 °C) or heat stress (35/30 °C) in controlled growth chambers for 35 d. The growth and physiological analysis demonstrated that exogenous GABA application significantly improved heat tolerance of creeping bentgrass. Metabolic profiling found that exogenous application of GABA led to increases in accumulations of amino acids (glutamic acid, aspartic acid, alanine, threonine, serine, and valine), organic acids (aconitic acid, malic acid, succinic acid, oxalic acid, and threonic acid), sugars (sucrose, fructose, glucose, galactose, and maltose), and sugar alcohols (mannitol and myo-inositol). These findings suggest that GABA-induced heat tolerance in creeping bentgrass could involve the enhancement of photosynthesis and ascorbate-glutathione cycle, the maintenance of osmotic adjustment, and the increase in GABA shunt. The increased GABA shunt could be the supply of intermediates to feed the tricarboxylic acid cycle of respiration metabolism during a long-term heat stress, thereby maintaining metabolic homeostasis.
Highlights
The objectives of this study were 1) to examine whether increased GABA could improve heat tolerance in cool-season creeping bentgrass (Agrostis stolonifera) through physiological analysis and 2) to determine major metabolic pathways regulated by GABA that contribute to the improved heat tolerance through metabolic profiling
Leaf osmotic adjustment (OA) of both non- and GABA-treated plants increased after 14 d of heat stress and declined in untreated plants with prolonged heat stress duration, while it was maintained at a higher level in GABA-treated plants during heat stress
GABA-treated plants showed more than 5 times higher OA than untreated plants from 28 to 35 d of heat stress (Fig. 1E)
Summary
The objectives of this study were to examine whether increased GABA could improve heat tolerance in cool-season creeping bentgrass through physiological analysis, and to determine major metabolic pathways regulated by GABA through metabolic profiling. The objectives of this study were 1) to examine whether increased GABA could improve heat tolerance in cool-season creeping bentgrass (Agrostis stolonifera) through physiological analysis and 2) to determine major metabolic pathways regulated by GABA that contribute to the improved heat tolerance through metabolic profiling
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