The Defensive Role of Endogenous H2S in Brassica rapa against Mercury-Selenium Combined Stress.

Lifei Yang,Huimin Yang,Jian Chen,Haiyan Lu,Zhiwei Bian,Li Zhang

doi:10.3390/ijms23052854

Abstract

Plants are always exposed to the environment, polluted by multiple trace elements. Hydrogen sulfide (H2S), an endogenous gaseous transmitter in plant cells, can help plant combat single elements with excess concentration. Until now, little has been known about the regulatory role of H2S in response to combined stress of multiple elements. Here we found that combined exposure of mercury (Hg) and selenium (Se) triggered endogenous H2S signal in the roots of Brasscia rapa. However, neither Hg nor Se alone worked on it. In roots upon Hg + Se exposure, the defensive role of endogenous H2S was associated to the decrease in reactive oxygen species (ROS) level, followed by alleviating cell death and recovering root growth. Such findings extend our knowledge of plant H2S in response to multiple stress conditions.

Highlights

Heavy metal pollution poses a threat to biological systems, which is a serious problem worldwide
Further studies are needed to reveal the molecular mechanism for H2S-mediated detoxification of Hg + Se, our current results propose a novel role of endogenous H2S in regulating plant adaption upon multiple stress conditions at the same time
Roots were incubated in WSP-1 solution (15 μM) at 25 ◦C for 40 min followed by rinsing with distilled water

Summary

Introduction

Heavy metal pollution poses a threat to biological systems, which is a serious problem worldwide. Our previous study found synergistic toxic effect of Se and Hg on Brassica rapa, showing enhanced ROS accumulation and aggravated growth inhibition as compared to Se or Hg alone [10]. Hg + Se exposure increased root endogenous H ficient to help plants combat stress condition. Root length was negatively correlated to ROS and cell death, respectively, under the condition of altering endogenous H2S level (Figure 4E,F). It has been reported that H2S can protect both plant and mammalian cells from oxidative stress by repressing NADPH oxidase-dependent ROS generation [39,40]. Further studies are needed to reveal the molecular mechanism for H2S-mediated detoxification of Hg + Se, our current results propose a novel role of endogenous H2S in regulating plant adaption upon multiple stress conditions at the same time

Plant Culture, Treatment, and Chemicals

Evaluation of Endogenous H2S Level in Root

Evaluation of Total ROS Level in Root Tip

Evaluation of Cell Death in Root Tip

Evaluation of Oxidative Injury in Root

Statistical