Wang Mian, Zhu Yahui, Wang Pei, Gu Zhenxin, Yang Runqiang
College of Food Science and Technology, Whole Grain Food Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
College of Food Science and Technology, Tibet Agriculture and Animal Husbandry University, Linzhi 860000, China.
Antioxidants (Basel). 2021 Sep 6;10(9):1421. doi: 10.3390/antiox10091421.
It has been revealed that high NaCl stress (>60 mmol L) induced phenolics accumulation in barley seedlings, with γ-aminobutyric acid (GABA) playing a key role. Interestingly, low NaCl stimulus (20 mmol L) enhancing phenolics synthesis and growth of barley seedlings was also reported recently. Hence, exogenous GABA and its bio-synthesis inhibitor 3-mercaptopropionic acid (3-MP) were applied to reveal the mechanism of GABA regulating phenolics metabolism in barley seedlings treated with 20 mmol L NaCl. The contents of total phenolics and flavonoids significantly increased by 11.64% and 14.52% under NaCl, respectively. The addition of GABA further increased phenolics and flavonoids contents, especially for gallic acid, protocatechuic acid, caffeic acid, and quercetin, compared with NaCl treatment. Simultaneously, GABA increased the activities and mRNA levels of phenylalanine ammonia lyase (PAL), cinnamic acid 4-hydroxylase (C4H), and 4-coumalyl CoA ligase (4CL). The addition of 3-MP suppressed the above effects, except for increasing the protein levels of PAL, C4H, and 4CL. Low concentration of NaCl not only promoted growth, but also stimulated endogenous GABA metabolism to affect key enzymes activities and mRNA levels for phenolics synthesis in barley seedlings.
研究表明，高NaCl胁迫（>60 mmol/L）会诱导大麦幼苗中酚类物质积累，γ-氨基丁酸（GABA）在其中起关键作用。有趣的是，最近也有报道称低NaCl刺激（20 mmol/L）可增强大麦幼苗的酚类物质合成及生长。因此，应用外源GABA及其生物合成抑制剂3-巯基丙酸（3-MP）来揭示GABA对经20 mmol/L NaCl处理的大麦幼苗酚类物质代谢的调控机制。在NaCl处理下，总酚和黄酮类化合物的含量分别显著增加了11.64%和14.52%。与NaCl处理相比，添加GABA进一步提高了酚类和黄酮类化合物的含量，尤其是没食子酸、原儿茶酸、咖啡酸和槲皮素。同时，GABA提高了苯丙氨酸解氨酶（PAL）、肉桂酸4-羟化酶（C4H）和4-香豆酰辅酶A连接酶（4CL）的活性及mRNA水平。添加3-MP抑制了上述效应，但提高了PAL、C4H和4CL的蛋白质水平。低浓度的NaCl不仅促进生长，还刺激内源性GABA代谢，从而影响大麦幼苗中酚类物质合成的关键酶活性及mRNA水平。
