Higher accumulation of gamma-aminobutyric acid induced by salt stress through stimulating the activity of diamine oxidases in Glycine max (L.) Merr. roots.
Polyamines (PAs) are assumed to perform their functions through their oxidative product such as gamma-aminobutyric acid (GABA) formation. However, there is only limited information on the interrelation between PA degradation and GABA accumulation under salt stress. In order to reveal a quantitative correlation between PA oxidation and GABA accumulation, the effects of treatments with different NaCl concentrations, along with aminoguanidine (AG, a specific inhibitor of diamine oxidases (DAO; EC: 1.4.3.6)) and a recovery test from salt stress on endogenous free PAs, gamma-aminobutyric acid (GABA) accumulation and DAO activity were determined in roots of soybean [Glycine max (L.) Merr.] cultivar Suxie-1. The results showed that the levels of putrescine (Put), cadaverine (Cad), and spermidine (Spd) decreased significantly with increasing salt concentrations. This occurred because salt stress strongly promoted DAO activity to stimulate PA degradation. GABA accumulation increased with growing NaCl concentrations, about an 11- to 17-fold increase as compared with the control plants. AG treatment increased the accumulation of endogenous free PAs as a result of a strong retardation of DAO activity, but decreased GABA accumulation. The recovery for 6 days in 1/2 Hoagland solution from 100mM NaCl stress resulted in a decrease in DAO activity, a rebound of PA levels and a simultaneous reduction of GABA content. A close correlation was observed between the changes in DAO activity and GABA accumulation. The results indicated that higher GABA accumulation (about 39%) induced by salt stress could come from PA degradation, suggesting that PAs might perform their functions through GABA formation under salt stress.
Xing
Su Guo
SG
College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P.R. China.
Jun
Yu Bing
YB
Hau
Zhang Wen
ZW
Liang
Liu You
LY
D006631:Amine Oxidase (Copper-Containing) / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D006146:Guanidines / Q000737:chemistry; D010100:Oxygen / Q000378:metabolism; D018521:Plant Physiological Phenomena; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism*; D011073:Polyamines / Q000737:chemistry*; D012492:Salts / Q000494:pharmacology*; D012965:Sodium Chloride / Q000737:chemistry; D013025:Glycine max / Q000378:metabolism; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis*
D006146:Guanidines; D011073:Polyamines; D012492:Salts; D012965:Sodium Chloride; D005680:gamma-Aminobutyric Acid; D006631:Amine Oxidase (Copper-Containing); D010100:Oxygen; C004479:pimagedine