Formaldehyde detoxification by the moss Racomitrium japonicum.

As a pervasive indoor air pollutant, formaldehyde (FA) poses significant environmental and health risks. This study investigates the molecular and physiological mechanisms underlying the FA remediation potential of the moss Racomitrium japonicum. The moss employs a dual defense strategy: activation of antioxidant systems (SOD/POD/CAT enzymes and AsA-GSH cycle) under moderate FA stress, and metabolic detoxification via upregulation of key genes (FDH, formate dehydrogenase, and MS, malate synthase) that channel FA into the Calvin cycle and glyoxylate pathway. High FA concentrations induced oxidative damage, reducing photosynthetic efficiency (27.4 % decline in Fv/Fm and 63.9 % in chlorophyll content) while triggering protective mechanisms like cyclic electron flow. Metabolomic analysis revealed accumulation of stress-responsive compounds (L-glutamine, putrescine), and the moss's unique leaf morphology enhanced FA adsorption. These findings delineate the molecular and physiological underpinnings of R. japonicum's FA tolerance, thereby supporting its further assessment as a promising candidate for integration into biological air purification systems tailored to indoor environments.