Abstract
NaCl stress causes oxidative stress in plants; γ-aminobutyric acid (GABA) could alleviate such abiotic stress by enhancing the synthesis of phenolics, but the underlying mechanism is not clear. We investigated the effects of GABA on phenolics accumulation in soybean sprouts under NaCl stress by measuring changes in the content of physiological biochemicals and phenolic substances, in the activity and gene expression of key enzymes, and in antioxidant capacity. GABA reduced the oxidative damage in soybean sprouts caused by NaCl stress and enhanced the content of total phenolics, phenolic acids, and isoflavones by 16.58%, 22.47%, and 3.75%, respectively. It also increased the activities and expression of phenylalanine ammonia lyase, cinnamic acid 4-hydroxylase, and 4-coumarate coenzyme A ligase. Furthermore, GABA increased the activity of antioxidant enzymes and the antioxidant capacity. These events were inhibited by 3-mercaptopropionate (an inhibitor for GABA synthesis), indicating that GABA mediated phenolics accumulation and antioxidant system enhancement in soybean sprouts under NaCl stress.
Highlights
Since phenolics are not related to GABA metabolism, it is speculated that GABA acts as a signal molecule to mediate the synthesis of phenolics in soybean sprouts
The present study showed that NaCl stress increased the content of total phenolics, phenolic acids, and isoflavones in soybean sprouts and their antioxidant capacity [7]
The results showed that, similar to the change observed in total phenolics content, NaCl stress increased the activities of CAT, POD, and Super oxide dimutese (SOD) in soybean sprouts and significantly enhanced DPPH and ABTS freeradical scavenging capacities
Summary
GABA increased the activity of antioxidant enzymes and the antioxidant capacity These events were inhibited by 3-mercaptopropionate (an inhibitor for GABA synthesis), indicating that GABA mediated phenolics accumulation and antioxidant system enhancement in soybean sprouts under NaCl stress. Soybean (Glycine max L.) is a key source of protein, fat, and functional carbohydrates [1] It contains some special phytochemicals [2] and is popular in East. Treatment of caragana roots with GABA under salt stress induced a variety of physiological and biochemical responses, such as signal transmission, protein degradation regulation, hormone synthesis, ROS formation, and polyamine metabolism [12], which indicates that GABA might be involved in the expression and regulation of salt-related genes in plants under salt stress. Whether GABA acts as a signal molecule and the exact mechanism of its action are Academic Editors: Filomena Nazzaro and Vincenzo De Feo
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