题名：Role of C4 carbon fixation in Ulva prolifera, the macroalga responsible for the world's largest green tides
来源：Nature Communications Biology
作者：Dongyan Liu﹡, Qian Ma, Ivan Valiela, Donald M. Anderson, John K. Keesing, Kunshan Gao, Yu Zhen, Xiyan Sun & Yujue Wang
Abstract Most marine algae preferentially assimilate CO2 via the Calvin-Benson Cycle (C3) and catalyze HCO3− dehydration via carbonic anhydrase (CA) as a CO2-compensatory mechanism, but certain species utilize the Hatch-Slack Cycle (C4) to enhance photosynthesis. The occurrence and importance of the C4 pathway remains uncertain, however. Here, we demonstrate that carbon fixation in Ulva prolifera, a species responsible for massive green tides, involves a combination of C3 and C4 pathways, and a CA-supported HCO3− mechanism. Analysis of CA and key C3 and C4 enzymes, and subsequent analysis of δ13C photosynthetic products showed that the species assimilates CO2 predominately via the C3 pathway, uses HCO3− via the CA mechanism at low CO2 levels, and takes advantage of high irradiance using the C4 pathway. This active and multi-faceted carbon acquisition strategy is advantageous for the formation of massive blooms, as thick floating mats are subject to intense surface irradiance and CO2 limitation. © 2020, The Author(s).
Role of C4 carbon fixation in Ulva prolifera the macroalga responsible for the world's largest green tides.pdf