
TY  - JOUR
A1  - Powles, SB 
A1  - Chapman, KSR 
A1  - Osmond, CB 
T1  - Photoinhibition of Intact Attached Leaves of C<sub>4</sub> Plants: Dependence on CO<sub>2</sub> and O<sub>2</sub> Partial Pressures
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1980
VL  - 7
IS  - 6
SP  - 737
EP  - 747
KW  - 
UR  - https://doi.org/10.1071/PP9800737 
N2  - Fully expanded intact attached leaves of Zea mays and other C4 plants illuminated at 2000 µE m-2 s-1 in CO2-free N2 containing 10 mbar O2 for a 3-h treatment period showed substantial inhibition of the capacity for both CO2-dependent and light-dependent CO2 assimilation. This photoinhibition was reflected at the chloroplast level as substantial inhibition of photosystem II activity of the mesophyll chloroplasts. Photoinhibition was largely insensitive to the O2 partial pressure maintained throughout the treatment period. This result suggests that internal CO2 generation by photorespiration with subsequent carbon cycling, or O2 uptake in a Mehler-type reaction are largely unable to alleviate photoinhibition. The extent of photoinhibition was, however, markedly affected by the CO2 partial pressure present throughout the treatment period. This result is consistent with the CO2-concentrating function of C4 photosynthesis, which allows substantial rates of CO2 assimilation even at low mesophyll CO2 partial pressures. Apparently, a certain level of CO2 turn- over is beneficial in providing a sink for photochemically generated energy, thereby maintaining the ability of illuminated leaves to transduce and dissipate light energy. 
ER  -

