Physiological and proteomic responses of mangrove plant Avicennia marina seedlings to simulated periodical inundation

Background and aims Avicennia marina is a pioneer mangrove species widely distributed along the southeast coast of China. It suffers, especially in the seedling stage, from the tidal flooding and anaerobic surroundings as it closes to the seaward side. The aim of this study is to assess the ability of A. marina seedlings to withstand different tidal inundations by physiological and proteomic approaches. Methods To accomplish this, the artificial tidal inundations were mimicked as 0, 4, and 8 h per tidal cycle about 1 week. The physiological approaches and two-dimensional electrophoresis coupled with MALDI-TOF/TOF-MS technology were used to reveal the adaptive alterations of A. marina seedlings to tidal inundation. Results There were profound changes in photosynthesis and chlorophyll fluorescence characteristics of A. marina seedling leaves under inundation treatment. Particularly, photosynthetic rate increased at 4 h inundation, while decreasing at 8 h inundation treatment compared with control (0 h). The results highlighted that A. marina seedlings could greatly upregulate the abundances of photosynthesis-related proteins, activate antioxidant and defense systems to efficiently suppress the reactive oxygen species (ROS) burst and cell damages, mobilize carbohydrate metabolism associated proteins, and then maintain cellular homeostasis, resulting in well adaptation to short-term tidal inundation. Conclusion Overall, our results demonstrated that short-term inundation is beneficial, while long-term inundation is detrimental to A. marina . The results allow us to recognize the roles of specific proteins in molecular tolerance to tidal inundation in mangrove plants.