Oxygenic Photoautotrophic Growth Without Photosystem I
J. W. Lee,
C. V. Tevault,
T. G. Owens,
E. Greenbaum
*
Contrary to the prediction of the Z-scheme model of
photosynthesis, experiments demonstrated that mutants of
Chlamydomonas containing photosystem II (PSII) but lacking
photosystem I (PSI) can grow photoautotrophically with O2
evolution, using atmospheric CO2 as the sole carbon source.
Autotrophic photosynthesis by PSI-deficient mutants was stable both
under anaerobic conditions and in air (21 percent O2) at an
actinic intensity of 200 microeinsteins per square meter per second.
This PSII photosynthesis, which was sufficient to support cell
development and mobility, may also occur in wild-type green algae and
higher plants. The mutants can survive under 2000 microeinsteins per
square meter per second with air, although they have less resistance to
photoinhibition.
J. W. Lee, C. V. Tevault, E. Greenbaum, Chemical Technology
Division, Oak Ridge National Laboratory, Post Office Box 2008, Oak
Ridge, TN 37831-6194, USA.
T. G. Owens, Section of Plant Biology, Cornell University, Ithaca, NY
14853, USA.
*
To whom correspondence should be addressed.
