CSIRO Publishing blank image blank image blank image blank imageBooksblank image blank image blank image blank imageJournalsblank image blank image blank image blank imageAbout Usblank image blank image blank image blank imageShopping Cartblank image blank image blank image You are here: Journals > Functional Plant Biology   
Functional Plant Biology
Journal Banner
  Plant Function & Evolutionary Biology
 
blank image Search
 
blank image blank image
blank image
 
  Advanced Search
   

Journal Home
About the Journal
Editorial Board
Contacts
Content
Online Early
Current Issue
Just Accepted
All Issues
Special Issues
Research Fronts
Reviews
Evolutionary Reviews
Sample Issue
For Authors
General Information
Notice to Authors
Submit Article
Open Access
For Referees
Referee Guidelines
Review Article
For Subscribers
Subscription Prices
Customer Service
Print Publication Dates

blue arrow e-Alerts
blank image
Subscribe to our Email Alert or RSS feeds for the latest journal papers.

red arrow Connect with us
blank image
facebook twitter youtube

red arrow PrometheusWiki
blank image
PrometheusWiki
Protocols in ecological and environmental plant physiology

 

Article << Previous     |     Next >>   Contents Vol 36(11)

Feedback limitation of photosynthesis at high CO2 acts by modulating the activity of the chloroplast ATP synthase

Olavi Kiirats A, Jeffrey A. Cruz B, Gerald E. Edwards A, David M. Kramer B C

A School of Biological Sciences, Washington State University, Pullman, WA 99164-4238, USA.
B Institute of Biological Chemistry, 339 Clark Hall, Washington State University, Pullman, WA 99164-6340, USA.
C Corresponding author. Email: dkramer@wsu.edu
This paper originates from a presentation at the 1st International Plant Phenomics Symposium, Canberra, Australia, April 2009.
 
PDF (454 KB) $25
 Export Citation
 Print
  


Abstract

It was previously shown that photosynthetic electron transfer is controlled under low CO2 via regulation of the chloroplast ATP synthase. In the current work, we studied the regulation of photosynthesis under feedback limiting conditions, where photosynthesis is limited by the capacity to utilise triose-phosphate for synthesis of end products (starch or sucrose), in a starch-deficient mutant of Nicotiana sylvestris Speg. & Comes. At high CO2, we observed feedback control that was progressively reversed by increasing O2 levels from 2 to 40%. The activity of the ATP synthase, probed in vivo by the dark-interval relaxation kinetics of the electrochromic shift, was proportional to the O2-induced increases in O2 evolution from PSII (JO2), as well as the sum of Rubisco oxygenation (vo) and carboxylation (vc) rates. The altered ATP synthase activity led to changes in the light-driven proton motive force, resulting in regulation of the rate of plastoquinol oxidation at the cytochrome b6f complex, quantitatively accounting for the observed control of photosynthetic electron transfer. The ATP content of the cell decreases under feedback limitation, suggesting that the ATP synthesis was downregulated to a larger extent than ATP consumption. This likely resulted in slowing of ribulose bisphosphate regeneration and JO2). Overall, our results indicate that, just as at low CO2, feedback limitations control the light reactions of photosynthesis via regulation of the ATP synthase, and can be reconciled with regulation via stromal Pi, or an unknown allosteric affector.

Keywords: electrochromic shift, in vivo spectroscopy, non-photochemical, proton motive force, quenching, regulation.


   
Subscriber Login
Username:
Password:  

    
Legal & Privacy | Contact Us | Help

CSIRO

© CSIRO 1996-2014