Hydrogen gas mediates ascorbic acid accumulation and antioxidant system enhancement in soybean sprouts under UV-A irradiation

Li Jia,Jin Cui,Shengjun Wei,Zhenguo Shen,Xiaoyan Zhang,Xuan Xu,Wenbiao Shen,Jiyuan Tian

doi:10.1038/s41598-017-16021-0

Abstract

The soybean sprout is a nutritious and delicious vegetable that is rich in ascorbic acid (AsA). Hydrogen gas (H2) may have potential applications in the vegetable processing industry. To investigate whether H2 is involved in the regulation of soybean sprouts AsA biosynthesis under UV irradiation, we set 4 different treatments: white light(W), W+HRW, UV-A and UV-A+HRW. The results showed that H2 significantly blocked the UV-A-induced accumulation of ROS, decreased TBARS content and enhanced SOD and APX activity in soybean sprouts. We also observed that the UV-A induced accumulation of AsA was enhanced more intensely when co-treated with HRW. Molecular analyses showed that UV-A+HRW significantly up-regulated AsA biosynthesis and recycling genes compared to UV-A in soybean sprouts. These data demonstrate that the H2 positively regulates soybean sprouts AsA accumulation under UV-A and that this effect is mediated via the up-regulation of AsA biosynthesis and recycling genes.

Highlights

The soybean (Glycine max L.) sprout is the most popular vegetable in East Asia because of its high nutritional value and good taste[1]
The variation tendency of ascorbic acid (AsA)+DHA was the same as AsA (Fig. 2B). These results showed that ultraviolet radiation (UV)-A significantly increased the AsA and AsA+DHA content in soybean sprouts and that hydrogen-rich water (HRW) further increased the AsA and AsA+DHA content
Our result shows that H2 can significantly release the inhibition of hypocotyl elongation induced by UV-A and boost fresh weight in soybean sprouts, HRW can obviously ease the oxidation damage caused by UV-A and increase AsA content in soybean sprouts

Summary

Introduction

The soybean (Glycine max L.) sprout is the most popular vegetable in East Asia because of its high nutritional value and good taste[1]. Green soybean sprouts have appeared in the market and have become widely accepted due to their colour and good mouthfeel In these green soybean sprouts, the synthesis of ascorbic acid, flavonoids and polysaccharides is significantly affected by light treatment[3]. Four pathways of AsA synthesis in plants have been proposed, including the L-galactose or Smirnoff-Wheeler (SW), D-galacturonic acid, L-glucose, and myo-inositol[14,15]. Among these proposed pathways, the L-galactose pathway is regarded as the major pathway for biosynthesis of AsA in plants[16]. The accumulation of AsA in plant tissues is regulated by an effective balance between biosynthesis and recycling[18]

Objectives

Methods

Results