《植物生理学报》 2015, 51(5): 679-685

海黍子对外源无机碳利用机制的初步研究

程苗^1,2, 吴海一^2,3,4, 詹冬梅^2,3, 绳秀珍¹, 徐智广^2,3,4,*

¹中国海洋大学水产学院, 山东青岛266003; ²山东省海洋生物研究院藻类研究中心, 山东青岛266104; ³青岛市大型海藻工程技术研究中心, 山东青岛266104; ⁴山东省海水健康养殖工程技术研究中心, 山东青岛266104

通信作者：徐智广；E-mail: bigwide@163.com；Tel: 18678919993

摘　要：

为了探讨海黍子的外源无机碳利用机制, 本文以光合放氧为指标研究了不同pH (6.5、8.0和9.5)及添加不同抑制剂(AZ、EZ和DIDS)对海黍子光合固碳特性的影响。结果显示, 随着外源碳浓度的增加, 海黍子的光合放氧速率逐渐增加, 随着pH的升高, 藻体的最大光合作用速率(V_max)逐渐降低, 而无机碳半饱和常数(K_0.5)逐渐升高。碳酸酐酶抑制剂acetazolamide (AZ)、6-ethoxyzolamide (EZ)及阴离子交换蛋白抑制剂4,4’-diisothiocyano-stilbene-2,2’-disulfonate (DIDS)对海黍子的光合固碳速率均有强烈的抑制作用。以上结果说明, 海黍子不仅对海水中的CO₂具有较高的亲和力, 而且还可以利用海水中的HCO₃^-作为光合作用的无机碳源, 且对HCO₃^-的吸收具备两条途径: 既可以通过胞外碳酸酐酶催化转化为CO₂后进入细胞, 也可通过阴离子交换蛋白直接吸收海水中的HCO₃^-。

关键词：海黍子; 光合固碳; AZ; EZ; DIDS

收稿：2014-11-12   修定：2015-03-27

资助：国家自然科学基金 (41376129)、海洋公益性行业科研专项经费项目(201305021、201405040、201505022和201305005)和青岛市市南区科技发展资金项目(2013-12-005-SW)。

Preliminary Study on Exogenous Inorganic Carbon Utilization in Sargassum muticum

CHENG Miao^1,2, WU Hai-Yi^2,3,4, ZHAN Dong-Mei^2,3, SHENG Xiu-Zhen¹, XU Zhi-Guang^2,3,4,*

¹Fishery College, Ocean University of China, Qingdao, Shandong 266003, China; ²Algal Research Centre, Marine Biology Institute of Shandong Province, Qingdao, Shandong 266104, China; ³Macroalgae Engineering Technology Centre of Qingdao, Qingdao, Shandong 266104, China; ⁴Engineering Research Center of Healthy Marine Aquaculture of Shandong Province, Qingdao, Shandong 266104, China

Corresponding author: XU Zhi-Guang; E-mail: bigwide@163.com; Tel: 18678919993

Abstract:

The inorganic carbon utilization in Sargassum muticum was investigated under different pH (6.5, 8.0 and 9.5) and different inhibitors (AZ, EZ and DIDS). The results showed that photosynthetic O₂ evolution rates in S. muticum increased gradually with increasing exogenous inorganic carbon concentration. V_max declined while K_0.5 rose remarkably along with increasing pH level. Both of carbonic anhydrase inhibitors [acetazolamide (AZ) or ethoxyzolamide (EZ)] and anion exchanger inhibitor [4,4’-diisothiocyano-stilbene-2,2’-disulfonate (DIDS)] notably suppressed photosynthetic O₂ evolution rates of S. muticum. These results suggested that S. muticum not only had a high affinity for CO₂, but also could use HCO₃^- as a source of Ci for photosynthesis. Moreover, two ways to use HCO₃^- were found in this alga, one was transforming HCO₃^- into CO₂ through carbonic anhydrase outside of the cell membrane, and the other was absorbing HCO₃^- directly by anion-exchange protein.

Key words: Sargassum muticum; photosynthetic carbon fixation; AZ; EZ; DIDS