Regulation of nutrient accumulation by γ-aminobutyric acid associated with GABA priming-enhanced heat tolerance in creeping bentgrass

Abstract

<italic>γ</italic>-Aminobutyric acid (GABA) is known for its positive effects on improving plant stress tolerance, while the association of its role in regulating nutritional availability and GABA priming-enhanced heat tolerance is not well documented. The objective of this study was to determine whether GABA priming may improve heat tolerance in cool-season grass species involving regulation of plant nutrition for macronutrients and micronutrient elements. Plants of creeping bentgrass (<italic>Agrostis stolonifera</italic>) (cv. 'Penncross') in each pot were treated with 10 mL of water (control) or 0.5 mM GABA (GABA priming) by foliar spray and then subjected to heat stress (35/30 °C, day/night) or optimal growth temperature (control) (21/19 °C, day/night) (non-stress control) for 30 d in growth chambers. GABA-primed plants had significantly higher endogenous GABA content associated with improved heat tolerance compared to non-treated plants, as reflected by higher leaf cell membrane stability, relative water content, osmotic adjustment, chlorophyll content, photochemical efficiency, and net photosynthetic rate. Plants pretreated with GABA exhibited significantly higher content of nitrogen (N), phosphorus (P), calcium (Ca), sodium (Na), and copper (Cu) but lower content of boron (B) and manganese (Mn) in leaves than non-treated plants under heat stress. The enhanced accumulation of N, P, Ca, Na, and Cu and restricted B and Mn accumulation by GABA priming indicate that GABA could modulate mineral nutrient availability in plants, contributing to improved heat tolerance for creeping bentgrass.