title: Effects of exogenous GABA on gene expression of Caragana intermedia roots under NaCl stress: regulatory roles for H2O2 and ethylene production.
abstract: gamma-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 H(2)O(2)-generated genes, NADPH oxidase (CaGR60), peroxidase (CaGR61) and amine oxidase (CaGR62), were regulated at the mRNA level by 10 mm GABA, which clearly inhibited H(2)O(2) accumulation brought about by NaCl stress in roots and leaves with the observation of 3,3'-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 H(2)O(2)-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.
authors.affiliation: Institute of Forestry Research, Chinese Academy of Forestry, 1958 Box, Beijing, 100091, China.
authors.forename: Sheng-Qing
authors.initials: SQ
authors.lastname: Shi
authors.forename: Zheng
authors.initials: Z
authors.lastname: Shi
authors.forename: Ze-Ping
authors.initials: ZP
authors.lastname: Jiang
authors.forename: Li-Wang
authors.initials: LW
authors.lastname: Qi
authors.forename: Xiao-Mei
authors.initials: XM
authors.lastname: Sun
authors.forename: Chun-Xiu
authors.initials: CX
authors.lastname: Li
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Liu
authors.forename: Wen-Fa
authors.initials: WF
authors.lastname: Xiao
authors.forename: Shou-Gong
authors.initials: SG
authors.lastname: Zhang
mesh_terms: D032602:Caragana / Q000187:drug effects / Q000235:genetics*; D005030:Ethylenes / Q000096:biosynthesis*; D020224:Expressed Sequence Tags; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D015723:Gene Library; D017343:Genes, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D018749:RNA, Plant / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
chemical_list: D005030:Ethylenes; D012333:RNA, Messenger; D018749:RNA, Plant; D012965:Sodium Chloride; D005680:gamma-Aminobutyric Acid; C036216:ethylene; D006861:Hydrogen Peroxide; D010088:Oxidoreductases