The sporogenesis is partly regulated by oxidative signal in Ulva prolifera: A physiological and transcriptomic perspective

The effect and mechanism of reactive oxygen species (ROS) in the sporogenesis of Ulva prolifera, the dominant species of green tide bloom, was unrevealed. In this study, we compared the levels of ROS contents and anti-oxidant capacities including antioxidant enzymes and non-enzymatic antioxidants in four states (vegetative cell, chloroplasts displaced, spore formation and matured spore, noted as state I, state II, state III and state IV, respectively) during sporogenesis in U. prolifera. Furthermore, changes in transcriptions of antioxidant enzymes were also investigated. The results showed that 1) the ROS, especially the superoxide radical (O2- ) content, was significantly enhanced during the early sporogenesis. The antioxidant capacity increased with the spore for-mation, especially the glutathione reductase (GR) and glutathione disulfide (GSSG) and tocopherols (VE), which was also consistent with the expression of relative genes during the spore formation. 2) The up-regulation of the MAPK is associated with the sporogenesis in U. prolifera. 3) the sporogenesis was inhibited by the presence of the 0.5 and 1 mmol L-1 of GSH, and the cell was dead in the 2 mmol L-1 conditions. The results showed that the antioxidant signal may participate in the spore formation.

Automated summary

This study reveals the effect and mechanism of reactive oxygen species (ROS) in the sporogenesis of Ulva prolifera, the dominant species of green tide bloom. It shows that the ROS content is significantly enhanced during the early sporogenesis and the antioxidant capacity increases with spore formation. The up-regulation of MAPK is associated with sporogenesis and the presence of GSH can inhibit sporogenesis.