Bio:
2015 PhD, Environmental Science Major, Group of Marine Proteomics, College of the Environment & Ecology, Xiamen University, China

2011 Master, Environmental Science Major, Group of Marine Proteomics, College of the Environment & Ecology, Xiamen University, China

2009, Bachelor, Environmental Engineering Major, College of the Environment and Materials Engineering, Yantai University, China

Abstract:
Dinoflagellates have drawn worldwide concerns as their large contributions to global primary production and negative impacts of harmful blooms to marine ecosystem. Although considerable efforts have devoted to their life activities, knowledge of the CO2 assimilation mechanism still lacks. Here, we first proved the existence of C4 cycle in a marine dinoflagelate Prorocentrum donghaiense with transcriptomics, metaproteomics and isotope techniques. Then, we compared the response of C4 photosynthesis to environmental changes of varied CO2 concentration, temperature and nitrogen resources. Significant negative correlations between pCO2 value and phytoplankton biomass were observed in laboratory-simulated and the field blooming progress. Under the CO2 exhaustion condition, cells of P. donghaiense activated C4 cycle to utilize intracellular HCO3- and highly expressed RubisCO to fix enough CO2 for growth. The growth rate of P. donghaiense increased when temperature rose from 19 ℃ to 25 ℃ and kept stable from 25 ℃ to 28 ℃. In low temperature below 25 ℃, cells of P. donghaiense expressed higher abundance of RubisCO to offset the negative effects of lower enzyme activity. Similar abundance of gene RubisCO and lower abundance of C4 genes were observed in 28 ℃, which might be attributed to the high diffusion rate of CO2 in high temperature. No difference of the growth rate and RubisCO abundance was identified when cells of P. donghaiense grew in sole medium of nitrate, ammonia and urea. However, lower expressions of carbonic anhydrase and C4 genes were observed in urea system, indicating urea can be served as CO2 resources and cells of P. donghaiense reduced extracellular CO2 uptake to cut down energy consumption. Our study deepened the knowledge of C4 photosynthesis in marine dinoflagellates, and also highlighted the viral adaptive response of CO2 assimilation pathways to varied environmental changes.