The molecular mechanisms underlying hydrogen peroxide regulating free-living conchocelis maturation of Pyropia...

The transition from conchocelis to conchosporangial branches is not only a key stage in the life cycle of Pyropia/Porphyra but also directly affects the yield and quality of economically important species such as Pyropia haitanensis. However, the molecular mechanisms underlying the maturation of P. haitanensis filaments remain poorly understood. Hydrogen peroxide (H₂O₂), as an important signaling molecule, plays a significant role in algae development. This study demonstrated that treatment with the H₂O₂ scavenger DMTU (500 μmol/L) significantly reduced H₂O₂ and O₂ ^- levels within the algae, affecting the activity of antioxidant enzymes and the content of antioxidant substances. This disrupted the ROS balance, inhibited key pathways such as photosynthesis and nitrogen metabolism, and triggered dysregulation in downstream metabolite synthesis. Consequently, the levels of most amino acids and their derivatives, nucleotides, and lipids were decreased. This diverted energy and resources from the "maturation program" towards a "stress-response program," thereby delaying conchocelis maturation. Notably, this inhibitory effect was reversible following DMTU removal. When unfavorable conditions necessitate delayed maturation induction, intervention with DMTU could be applied to effectively reduce the risk of conchospore "abortion". In summary, H₂O₂ is a critical signaling molecule regulating the maturation of P. haitanensis conchocelis. This study provides a theoretical basis for elucidating the molecular regulatory network governing conchocelis maturation in Pyropia/Porphyra and achieving precise regulation of synchronized maturation.