Two Photosynthetic Mechanisms Mediating the Low Photorespiratory State in Submersed Aquatic Angiosperms

Two Photosynthetic Mechanisms Mediating the Low Photorespiratory State in Submersed Aquatic... The submersed angiosperms Myriophyllum spicatum L. and Hydrilla verticillata (L.f.) Royal exhibited different photosynthetic pulse-chase labeling patterns. In Hydrilla , over 50% of the 14 C was initially in malate and aspartate, but the fate of the malate depended upon the photorespiratory state of the plant. In low photorespiration Hydrilla , malate label decreased rapidly during an unlabeled chase, whereas labeling of sucrose and starch increased. In contrast, for high photorespiration Hydrilla , malate labeling continued to increase during a 2-hour chase. Thus, malate formation occurs in both photorespiratory states, but reduced photorespiration results when this malate is utilized in the light. Unlike Hydrilla , in low photorespiration Myriophyllum , 14 C incorporation was via the Calvin cycle, and less than 10% was in C 4 acids. Ethoxyzolamide, a carbonic anhydrase inhibitor and a repressor of the low photorespiratory state, increased the label in glycolate, glycine, and serine of Myriophyllum . Isonicotinic acid hydrazide increased glycine labeling of low photorespiration Myriophyllum from 14 to 25%, and from 12 to 48% with high photorespiration plants. Similar trends were observed with Hydrilla . Increasing O 2 increased the per cent ( 14 C)glycine and the O 2 inhibition of photosynthesis in Myriophyllum . In low photorespiration Myriophyllum , glycine labeling and O 2 inhibition of photosynthesis were independent of the CO 2 level, but in high photorespiration plants the O 2 inhibition was competitively decreased by CO 2 . Thus, in low but not high photorespiration plants, glycine labeling and O 2 inhibition appeared to be uncoupled from the external (O 2 )/(CO 2 ) ratio. These data indicate that the low photorespiratory states of Hydrilla and Myriophyllum are mediated by different mechanisms, the former being C 4 -like, while the latter resembles that of low CO 2 -grown algae. Both may require carbonic anhydrase to enhance the use of inorganic carbon for reducing photorespiration. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png

Two Photosynthetic Mechanisms Mediating the Low Photorespiratory State in Submersed Aquatic Angiosperms

Loading next page...
1
 
/lp/american-society-of-plant-biologist/two-photosynthetic-mechanisms-mediating-the-low-photorespiratory-state-oyw9QzALBJ
Publisher
American Society of Plant Biologist
Copyright
Copyright © 1983 by the American Society of Plant Biologists
ISSN
1532-2548
eISSN
0032-0889
D.O.I.
10.1104/pp.73.2.488
Publisher site
See Article on Publisher Site

Abstract

The submersed angiosperms Myriophyllum spicatum L. and Hydrilla verticillata (L.f.) Royal exhibited different photosynthetic pulse-chase labeling patterns. In Hydrilla , over 50% of the 14 C was initially in malate and aspartate, but the fate of the malate depended upon the photorespiratory state of the plant. In low photorespiration Hydrilla , malate label decreased rapidly during an unlabeled chase, whereas labeling of sucrose and starch increased. In contrast, for high photorespiration Hydrilla , malate labeling continued to increase during a 2-hour chase. Thus, malate formation occurs in both photorespiratory states, but reduced photorespiration results when this malate is utilized in the light. Unlike Hydrilla , in low photorespiration Myriophyllum , 14 C incorporation was via the Calvin cycle, and less than 10% was in C 4 acids. Ethoxyzolamide, a carbonic anhydrase inhibitor and a repressor of the low photorespiratory state, increased the label in glycolate, glycine, and serine of Myriophyllum . Isonicotinic acid hydrazide increased glycine labeling of low photorespiration Myriophyllum from 14 to 25%, and from 12 to 48% with high photorespiration plants. Similar trends were observed with Hydrilla . Increasing O 2 increased the per cent ( 14 C)glycine and the O 2 inhibition of photosynthesis in Myriophyllum . In low photorespiration Myriophyllum , glycine labeling and O 2 inhibition of photosynthesis were independent of the CO 2 level, but in high photorespiration plants the O 2 inhibition was competitively decreased by CO 2 . Thus, in low but not high photorespiration plants, glycine labeling and O 2 inhibition appeared to be uncoupled from the external (O 2 )/(CO 2 ) ratio. These data indicate that the low photorespiratory states of Hydrilla and Myriophyllum are mediated by different mechanisms, the former being C 4 -like, while the latter resembles that of low CO 2 -grown algae. Both may require carbonic anhydrase to enhance the use of inorganic carbon for reducing photorespiration.

There are no references for this article.

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create folders to
organize your research

Export folders, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off