The Hydrogen Sulfide Donor NaHS Delays Programmed Cell Death in Barley Aleurone Layers by Acting as an Antioxidant.

Long Ruan,Xi-Qi Zhang,Kai Lv,Kang-Di Hu,Ying-Xin Zhang,Lan-Ying Hu,Hua Zhang,Yan-Hong Li,Yong-Sheng Liu

doi:10.1155/2015/714756

Abstract

H2S is a signaling molecule in plants and animals. Here we investigated the effects of H2S on programmed cell death (PCD) in barley (Hordeum vulgare L.) aleurone layers. The H2S donor NaHS significantly delayed PCD in aleurone layers isolated from imbibed embryoless barley grain. NaHS at 0.25 mM effectively reduced the accumulation of superoxide anion (·O2 −), hydrogen peroxide (H2O2), and malondialdehyde (MDA), promoted the activity of superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), and decreased those of lipoxygenase (LOX) in isolated aleurone layers. Quantitative-PCR showed that NaHS treatment of aleurone tissue led to enhanced transcript levels of the antioxidant genes HvSOD1, HvAPX, HvCAT1, and HvCAT2 and repressed transcript levels of HvLOX (lipoxygenase gene) and of two cysteine protease genes HvEPA and HvCP3-31. NaHS treatment in gibberellic acid- (GA-) treated aleurone layers also delayed the PCD process, reduced the content of ·O2 −, and increased POD activity while decreasing LOX activity. Furthermore, α-amylase secretion in barley aleurone layers was enhanced by NaHS treatment regardless of the presence or absence of GA. These data imply that H2S acted as an antioxidant in delaying PCD and enhances α-amylase secretion regardless of the presence of GA in barley aleurone layers.

Highlights

Programmed cell death (PCD), a response of plants to biotic and abiotic stresses, can occur during the normal course of development [1]
9% of cells die in aleurone layers treated with 0.25 mM NaHS while approximately 67% of cells of aleurone layers incubated in water undergo PCD
Because Reactive oxygen species (ROS) are tightly associated with the promotion of PCD in barley aleurone cells [6], we examine the contents of ⋅O2−, H2O2, and MDA in non-gibberellic acid- (GA-)treated barley aleurone layers in the presence and absence of NaHS

Summary

Introduction

Programmed cell death (PCD), a response of plants to biotic and abiotic stresses, can occur during the normal course of development [1]. PCD in barley aleurone layers occurs only after cells become highly vacuolated and is accompanied with loss of plasma membrane integrity and increased cysteine protease activity [3]. Intracellular H2O2 overproduction or exogenous H2O2 application results in a rapid death in GA-treated aleurone protoplasts [6]. Antioxidant enzymes such as catalase (CAT), guaiacol peroxidase (POD), ascorbate peroxidase (APX), and superoxide dismutase (SOD) are responsible for ROS scavenging, thereby keeping homeostatic levels of ROS. The increase in cysteine protease and aspartic protease activities is observed in GA-treated barley aleurone layers [2]

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Discussion

Conclusion