The Defensive Role of Endogenous H(2)S in Brassica rapa against Mercury-Selenium Combined Stress

Plants are always exposed to the environment, polluted by multiple trace elements. Hydrogen sulfide (H(2)S), 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 H(2)S in response to combined stress of multiple elements. Here we found that combined exposure of mercury (Hg) and selenium (Se) triggered endogenous H(2)S 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 H(2)S 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 H(2)S in response to multiple stress conditions.