Effects of formaldehyde stress on electron transport and reactive oxygen species in moss Racomitrium japonicum L.

Formaldehyde is a common gaseous pollutant from buildings and decorative materials. However, in recent years, increasing concerns have been raised regarding its harmful health in indoor air. Therefore, this study aims to investigate the physiological and photosynthetic response mechanisms of Racomitrium japonicum under formaldehyde stress. R. japonicum was exposed to dynamic fumigation with formaldehyde for 7 days, with each day comprising an 8-h exposure period within a sealed container. The effects on plant structure, pigment content, photosynthetic efficiency, and reactive oxygen species (ROS) generation were assessed. Our findings revealed that formaldehyde stress led to structural damage, reduced pigment content, decreased photosynthetic efficiency, and increased ROS production in R. japonicum . Significantly, distinct stress-response pathways were observed at various formaldehyde concentrations. In response to low and moderate formaldehyde concentrations, R. japonicum activated its antioxidant enzyme system to mitigate ROS accumulation. In contrast, the high-concentration treatment group demonstrated suppressed antioxidant enzyme activity. In response, R. japonicum used non-photochemical quenching and activated cyclic electron flow to mitigate severe cellular damage. This study provides an in-depth understanding of the physiological changes of R. japonicum under formaldehyde stress, elucidating its response mechanisms. The findings provide valuable information for developing effective indoor formaldehyde monitoring and purification methods.