Unravelling Chilling-stress Resistance Mechanisms in Endangered Mangrove Plant Lumnitzera littorea (Jack) Voigt

Mangrove plants are the demonstrated woody plants in tropical and subtropical coastal area with great ecological and economic importance. However, due to the extreme global climate change and increased human activities, mangroves is suffering a dramatic declining worldwide. Lumnitzera littorea (Jack) Voigt is one of the most endangered mangrove species in China. A comprehensive understanding on its resistance mechanisms to low ambient temperature help us to better conserve and restore L. littorea. In the current study, we performed comparative transcriptome analysis to investigate the genome-wide changes of gene expression profile in L. littorea under chilling stress (8°C day/5°C night) over normal condition (25°C day/23°C night). The low temperature suppressed fatty acid elongation and protein phosphorylation in L. littorea, while induced calcium ion binding process and signaling transduction, suggesting an activation of cold-stress sensing and signaling in L. littorea. Combining our analysis with our previous physiological assays, we showed a substantial photoinhibition occurring in the seedlings of L. littorea with the decrease of ambient temperature, and the synthesis of photosystem II reaction center protein D1 and peroxidase-involved scavenging of reactive oxygen species (ROS) were enhanced accordingly to combat the adverse impacts. Finally, we highlighted the biological significance of post-transcriptional regulation, including RNA binding and surveillance, in coping with cold stress in L. littorea. Collectively, our findings provide a global view to the resistance mechanisms of chilling stress in L. littorea, and valuable genetic resources to assist the protection and restoration of L. littorea. To investigate the molecular mechanisms underlying cold-stress resistance in L. littorea, we conducted comparative transcriptome analysis for the seedlings grown under normal condition (the growth temperature of 25°C day/23°C night, CK) and chilling stress (8°C day/5°C night, CT).