角苔（角苔纲）中基于蛋白核的二氧化碳浓缩机制的变异性。

Variability of the pyrenoid-based CO2 concentrating mechanism in hornworts (Anthocerotophyta).

作者信息

Hanson David, Andrews T John, Badger Murray R

机构信息

Molecular Plant Physiology Group, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 2601, Australia.Corresponding author; email:

Molecular Plant Physiology Group, Research School of Biological Sciences, Institute of Advanced Studies, The Australian National University, GPO Box 475, Canberra, ACT 2601, Australia.

出版信息

Funct Plant Biol. 2002 Apr;29(3):407-416. doi: 10.1071/PP01210.

DOI:10.1071/PP01210

PMID:32689485

Abstract

Hornworts (Anthocerotophyta) are the only group of land plants with pyrenoid-containing chloroplasts. CO2 exchange and carbon isotope discrimination values (ΔC) values have previously demonstrated the presence of a CO2 concentrating mechanism (CCM) in some pyrenoid-containing species. We have examined hornwort CCM function by using a combined fluorometer/mass spectrometer based technique to compare pyrenoid-containing (PhaeocerosProsk. and Notothylas Sull.) and pyrenoid-lacking (Megaceros Campbell) hornworts, with the liverwort Marchantia polymorphaL. that has standard C3 photosynthesis and a thalloid growth form similar to hornworts. We found that Notothylas has more CCM activity than Phaeoceros, and that Megaceros has the least CCM activity. Notothylas and Phaeoceros had compensation points from 11-13 parts per million (ppm) CO2, lower K0.5(CO2) than Marchantia, negligible photorespiration, and they accumulate a pool of dissolved inorganic carbon (DIC) between 19-108 nmol mg chlorophyll. Megaceroshad an intermediate compensation point of 31 ppm CO2 (compared with 64 ppm CO2 in Marchantia), a lower K0.5(CO2) than Marchantia, and some photorespiration, but no DIC pool. We also determined the catalytic rate of carboxylation per active site of Rubisco for all four species (Marchantia, 2.6 s; Megaceros, 3.3 s; Phaeoceros, 4.2 s; Notothylas 4.3 s), and found that Rubisco content was 3% of soluble protein for pyrenoid-containing species, 4% for Megaceros and 8% for Marchantia.

摘要

角苔纲植物（Anthocerotophyta）是唯一一类含有蛋白核叶绿体的陆地植物。此前，二氧化碳交换和碳同位素分馏值（ΔC）已证明一些含蛋白核的物种存在二氧化碳浓缩机制（CCM）。我们使用基于荧光计/质谱仪的组合技术，对角苔纲植物的CCM功能进行了研究，以比较含蛋白核的角苔（Phaeoceros Prosk.和Notothylas Sull.）、不含蛋白核的角苔（Megaceros Campbell），以及具有标准C3光合作用且叶状体生长形式与角苔相似的地钱（Marchantia polymorpha L.）。我们发现，Notothylas的CCM活性高于Phaeoceros，而Megaceros的CCM活性最低。Notothylas和Phaeoceros的二氧化碳补偿点为11 - 13 ppm，K0.5（CO2）低于地钱，光呼吸可忽略不计，并且它们积累了19 - 108 nmol mg叶绿素的溶解无机碳（DIC）库。Megaceros的中间二氧化碳补偿点为31 ppm（相比之下，地钱为64 ppm），K0.5（CO2）低于地钱，有一些光呼吸，但没有DIC库。我们还测定了所有四个物种（地钱、Megaceros、Phaeoceros、Notothylas）每个Rubisco活性位点的羧化催化速率（地钱为2.6 s；Megaceros为3.3 s；Phaeoceros为4.2 s；Notothylas为4.3 s），并发现对于含蛋白核的物种，Rubisco含量占可溶性蛋白的3%，Megaceros为4%，地钱为8%。