Gaseous signaling molecule H2S as a multitasking signal molecule in ROS metabolism of Oryza sativa under thiocyanate (SCN−) pollution
The induction of disruption in the electronic transport chain by thiocyanate (SCN − ) leads to an excessive generation of reactive oxygen species (ROS) within rice ( Oryza sativa ). Hydrogen sulfide (H 2 S) assumes a crucial role as a gaseous signaling molecule, holding significant potential in alleviating SCN − -related stress. Nevertheless, there remains a dearth of understanding regarding the intricate interplay between H 2 S and ROS in Oryza sativa amidst SCN − pollution. In this investigation, a hydroponics-based experiment was meticulously devised to explore how H 2 S-mediated modifications influence the genetic feedback network governing ROS metabolism within the subcellular organelles of Oryza sativa when exposed to varying effective concentrations (EC 20 : 24 mg SCN/L; EC 50 : 96 mg SCN/L; EC 75 : 300 mg SCN/L) of SCN − . The findings unveiled the enhanced capacity of Oryza sativa to uptake SCN − under H 2 S + SCN − treatments in comparison to SCN − treatments alone. Notably, the relative growth rate (RGR) of seedlings subjected to H 2 S + SCN − exhibited a superior performance when contrasted with seedlings exposed solely to SCN − . Furthermore, the application of exogenous H 2 S yielded a significant reduction in ROS levels within Oryza sativa tissues during SCN − exposure. To elucidate the intricacies of gene regulation governing ROS metabolism at the mRNA level, the 52 targeted genes were categorized into four distinct types, namely: initial regulatory ROS generation genes (ROS-I), direct ROS scavenging genes (ROS-II), indirect ROS scavenging genes (ROS-III), and lipid oxidation genes (ROS-IV). On the whole, exogenous H 2 S exhibited the capacity to activate the majority of ROS-I ∼ ROS-IV genes within both Oryza sativa tissues at the EC 20 concentration of SCN − . However, genetic positive/negative feedback networks emphasized the pivotal role of ROS-II genes in governing ROS metabolism within Oryza sativa . Notably, these genes were predominantly activated within the cytoplasm, chloroplasts, mitochondria, peroxisomes, and the cell wall.
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