The impact of GABA in harpin-elicited biotic stress responses in Nicotiana tabaccum

The versatile GABA in plants

“…10,137 For example, in cultured rice cells treated with a cell-wall elicitor of rice blast fungus (Magnaporthe grisea), the level of GABA increased 12.5-fold at 8 hours after treatment. 138 Similarly, GABA production is highly induced in stems of Jatropha curcas L. (Euphorbiaceae) infected with the Jatropha mosaic virus (JMV), 139 in tomato leaves infected by Botrytis cinereal, 140 in tobacco leaves infiltrated with a hairpin elicitor, 141 in leaves of potato plants after inoculation with potato virus Y, 142 in leaf apoplast of Phaseolus vulgaris inoculated with P. syringae pv. phaseolicola (Pph) 1302A, 143 in Arabidopsis infected with Fusarium graminearum, 144 in diseased Vitis vinifera, 145 and in lettuce inoculated with gray mold.…”

“…150 In plants, GABA plays an important role in central C/N metabolism by connecting amino acid metabolism to the tricarboxylic acid (TCA) cycle (see the detailed text in section 5 "C: N balance" below). In plant-microbe interactions, GABA contents increase due to the elevated GAD enzyme activity.- 141,149 Then GABA enters into the TCA cycle to maintain cell viability via alteration in C: N metabolism. 139,140 Consequently, GABA activates antioxidant enzymes (peroxidase, superoxide dismutase, and catalase) and limits the cell death that can be caused by excessive ROS.151 Thus, high GABA levels indicate plant resistance to pathogens.…”

GABA in plants: developmental and stress resilience perspective

“…Hairpin is an elicitor protein secreted by bacterial pathogens that triggers defense responses, including hypersensitive response, in plants. A hypothesis of an interaction between the hairpin elicitor and GABA shunt pathway was put forth, which leads to a conclusion that the Hairpin causes the induction of GDH, GAD, and glutamate, the first components of GABA shunt, ultimately activating the GABA response (Dimlioglu et al, 2015). Plant‐produced GABA was also shown to downregulate the quorum sensing signals in Agrobacterium tumefaciens to modulate its virulence (Chevrot et al, 2006).…”