Effects of exogenous GABA on gene expression of Caragana intermedia roots under NaCl stress: regulatory roles for H₂O₂ and ethylene production

Abstract

ABSTRACTg-aminobutyric acid (GABA) is a four-carbon non-protein amino acid presented in a wide range of organisms. In this study, a suppression subtractive hybridization (SSH) library was constructed using roots of a legume shrub, Caragana intermedia, with the combined treatment of 300 mM NaCl and 300 mM NaCl + 10 mM GABA. We obtained 224 GABA-regulated unique expressed sequence tags (ESTs) including signal transduction, transcriptional regulation, hormone biosynthesis, reactive oxygen species (ROS) and polyamine metabolism, etc. The key H2O2-generated genes, NADPH oxidase (CaGR60), peroxidase (CaGR61) and amine oxidase (CaGR62), were regulated at the mRNA level by 10 mM GABA, which clearly inhibited H2O2 accumulation brought about by NaCl stress in roots and leaves with the observation of 3,3Ј-diaminobenzidine (DAB) staining. Similarly, 10 mM GABA also regulated the expression of 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (ACO) genes (CaGR30 and CaGR31) and ethylene production in NaCl-treated roots. Surprisingly, these H2O2-generated genes were enhanced at the mRNA level by a lower concentration of GABA, at 0.25 mM, but not other alternative nitrogen sources, and endogenous GABA accumulated largely just by the application of GABA at either concentration. Our results further proved that GABA, as a signal molecule, participates in regulating the expression of genes in plants under salt stress.

γ-Aminobutyric acid (GABA) priming enhances the osmotic stress tolerance in Piper nigrum Linn. plants subjected to PEG-induced stress

“…Studies have revealed that pre-treatment with various compounds like non-protein amino acids, vitamins, polyamines, hormones and many other chemicals can induce a primed condition in plants exposed to various abiotic stresses and which help to alleviate the awful effects of the impending stress (Jakab et al 2005;Shi et al 2010;Jisha et al 2013;Deng et al 2014;Li et al 2015). Priming is comparatively simple and easily adoptable than other techniques like breeding or genetic engineering for stress tolerance.…”

“…Priming by exogenous application of c-aminobutyric acid (GABA) has been proven to influence some physiological activities in certain plants for defending various abiotic stresses (Barbosa et al 2010;Shi et al 2010;Song et al 2010;Nayyar et al 2013;Malekzadeh et al 2012Malekzadeh et al , 2014. In plants, GABA is synthesized endogenously and is involved in various metabolic activities.…”

Does GABA increase the efficiency of symbiotic N2fixation in legumes?

“…18 Later, an increase of the cytosolic Ca 2+ -concentration preceding the elevated GABA synthesis rate was reported, linking GABA synthesis to stress signaling. 19 Several papers have demonstrated the possible metabolic functions of GABA in various processes which might include cytosolic pH regulation, 20 protection against oxygen deficiency, 21 scavenging against reactive oxygen species (ROS), 22 temporary nitrogen storage 23 or plant defense against pests. 24 Additionally, in the recent years, the possibility that GABA might be involved in regulating plant growth and development has been raised.…”

Cloning and characterization of the UBC gene from lotus (Nelumbo nucifera)

“…These damaged proteins pose a significant threat to the plant if not degraded by protein-degrading enzymes in time. Ubiquitin degrades abnormal proteins through the ubiquitin pathway, in response to high temperature, drought, cold damage, radiation, and other forms of stress (Ingvardsen and Veierskov, 2001;Moon et al, 2004;Dreher and Callis, 2007;Shi et al, 2010). Abiotic low-temperature stress on N. nucifera resulted in down-regulated NnUBC3 expression.…”