Reactive oxygen species (ROS) induce the gametogenesis through regulating the expression of genes related to ontogenetic stage in gametophyte of Saccharina japonica

Abstract

The gametophyte clonal lines of Saccharina japonica have extremely important application values in aspects such as seedling cultivation and genetic resource conservation. Under unfavorable conditions, S. japonica gametophytes cease reproductive development and instead form multicellular clones through mitosis. However, under suitable conditions, these gametophytes can transition from vegetative growth to reproductive development. While extensive research has elucidated the environmental conditions that induce this transition, studies investigating the intrinsic regulatory mechanisms underlying this process remain exceedingly rare. Our findings indicate that treatment with H₂O₂ accelerated the transition from vegetative growth to reproductive development in gametophytes. During this critical phase, genes related to reactive oxygen species (ROS) scavenging enzymes, cell signaling, cell division and cell wall polysaccharide metabolism exhibited differential expression patterns. Notably, the differential expression of ROS scavenging enzymes led to H₂O₂ accumulation, which in turn induced changes in the expression of cell signaling-related genes. This process inhibited the Mitogen-Activated Protein Kinase (MAPK) signaling pathway, suppressing cell division. Concurrently, ROS differentially regulated genes associated with cell wall polysaccharide metabolism, inhibiting cell wall synthesis while enhancing its elasticity. This study will further deepen our understanding of the intrinsic regulatory mechanisms underlying kelp gametophyte reproductive development, and will contribute to the efficiency enhancement of the cultivation methods for kelp seedlings based on delayed gametophyte clone.