Physiological Mechanisms of the Enhanced UV-B Radiation Triggering Plant-Specific Peroxidase-Mediated Antioxidant Defences

In this study, an artificially simulated enhanced UV-B radiation treatment of 96 kJ/m²·d^-1 was applied with natural sunlight as the control. By observing changes in biological tissue damage, peroxidase (POD) enzyme activity, and hormone content, combined with transcriptome analysis and quantitative fluorescence PCR validation, this study preliminarily elucidated the physiological mechanisms of plant-specific peroxidase (POD) in responding to enhanced UV-B radiation stress. Enhanced UV-B treatment significantly inhibited biological tissue growth, particularly during the rapid growth stage. At this stage, the treatment exhibited higher malondialdehyde (MDA) content, indicating increased oxidative stress due to the accumulation of reactive oxygen species (ROS). Despite the inhibition in growth, the treatment showed improvements in the accumulation of organic nutrients as well as the contents of abscisic acid (ABA), salicylic acid (SA), and methyl jasmonate (MeJA). Additionally, an increase in POD activity and lignin content was observed in the treatment, especially during the middle period of the rapid growth period. Transcriptome analysis revealed that two POD multigene family members, <i>LOC123198833</i> and <i>LOC123225298</i>, were significantly upregulated under enhanced UV-B radiation, which was further validated through qPCR. In general, enhanced UV-B radiation triggered a defence response in biological tissue by upregulating POD genes, which can effectively help to scavenge excess ROS.