Photoinhibition of photosynthesis in intact bean leaves: role of light and temperature, and requirement for chloroplast-protein synthesis during recovery

✍ Scribed by D. H. Greer; J. A. Berry; O. Björkman

• Publisher: Springer-Verlag
• Year: 1986
• Tongue: English
• Weight: 788 KB
• Volume: 168
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00402971

✦ Synopsis

Photoinhibition of photosynthesis was induced in intact leaves of Phaseolus vulgaris L. grown at a photon flux density (PFD; photon fluence rate) of 300 gmol. m-2. s-1, by exposure to a PFD of 1400 ~tmol. m-2. s-1. Subsequent recovery from photoinhibition was followed at temperatures ranging from 5 to 35~ and at a PFD of either 20 or 140 gmol. m-2. s-1 or in complete darkness. Photoinhibition and recovery were monitored mainly by chlorophyll fluorescence emission at 77K but also by photosynthetic 02 evolution. The effects of the protein-synthesis inhibitors, cycloheximide and chloramphenicol, on photoinhibition and recovery were also determined. The results demonstrate that recovery was temperaturedependent with rates slow below 15 ~ C and optimal at 30 ~ C. Light was required for maximum recovery but the process was light-saturated at a PFD of 20 gmol. m-2. s-1. Chloramphenicol, but not cycloheximide, inactivated the repair process, indicating that recovery involved the synthesis of one or more chloroplast-encoded proteins. With chloramphenicol, it was shown that photoinhibition and recovery occurred concomitantly. The temperature-dependency of the photoinhibition process was, therefore, in part determined by the effect of temperature on the recovery process. Consequently, photoinhibition is the net difference between the rate of damage and the rate of repair. The susceptibility of chilling-sensitive plant species to photoinhibition at low temperatures is proposed to result from the low rates of recovery in this temperature range.