Methane (CH4), one of the most important greenhouse gases, has conventionally been considered as a physiologic inert gas. However, this perspective has been challenged by the observation that CH4 has diverse biological functions in animals, such as anti-inflammatory, antioxidant, and anti-apoptosis. Meanwhile, it has now been identified as a possible candidate of gaseous signaling molecule in plants, although its biosynthetic and metabolic pathways as well as the mechanism(s) of CH4 signaling have not fully understood yet. This paper aims to review the available evidence for the biological roles of CH4 in regulating plant physiology. Although currently available reports do not fully support the notion of CH4 as a gasotransmitter, they do show that CH4 might be produced by an aerobic, non-microbial pathway from plants, and plays important roles in enhancing plant tolerance against abiotic stresses, such as salinity, drought, heavy metal exposure, and promoting root development, as well as delaying senescence and browning. Further results showed that CH4 could interact with reactive oxygen species (ROS), other gaseous signaling molecules [e.g., nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S)], and glutathione (GSH). These reports thus support the idea that plant-produced CH4 might be a component of a survival strategy of plants. Finally, the possibility of CH4 application in agriculture is preliminarily discussed.
Keywords: Abiotic stress; Biological functions; Methane; Plant methanogenesis; Root organogenesis.