, Volume 186, Issue 1, pp 88–98

Functioning of photosystems I and II in pea leaves exposed to heat stress in the presence or absence of light

Analysis using in-vivo fluorescence, absorbance, oxygen and photoacoustic measurements
  • Michel Havaux
  • Hubert Greppin
  • Reto J. Strasser

DOI: 10.1007/BF00201502

Cite this article as:
Havaux, M., Greppin, H. & Strasser, R.J. Planta (1991) 186: 88. doi:10.1007/BF00201502


Fluorimetric, photoacoustic, polarographic and absorbance techniques were used to measure in situ various functional aspects of the photochemical apparatus of photosynthesis in intact pea leaves (Pisum sativum L.) after short exposures to a high temperature of 40 ° C. The results indicated (i) that the in-vivo responses of the two photosystems to high-temperature pretreatments were markedly different and in some respects opposite, with photosystem (PS) II activity being inhibited (or down-regulated) and PSI function being stimulated; and (ii) that light strongly interacts with the response of the photosystems, acting as an efficient protector of the photochemical activity against its inactivation by heat. When imposed in the dark, heat provoked a drastic inhibition of photosynthetic oxygen evolution and photochemical energy storage, correlated with a marked loss of variable PSII-chlorophyll fluorescence emission. None of the above changes were observed in leaves which were illuminated during heating. This photoprotection was saturated at rather low light fluence rates (around 10 W · m−2). Heat stress in darkness appeared to increase the capacity for cyclic electron flow around PSI, as indicated by the enhanced photochemical energy storage in far-red light and the faster decay of P700+(oxidized reaction center of PSI) monitored upon sudded interruption of the far-red light. The presence of light during heat stress reduced somewhat this PSI-driven cyclic electron transport. It was also observed that heat stress in darkness resulted in the progressive closure of the PSI reaction centers in leaves under steady illumination whereas PSII traps remained largely open, possibly reflecting the adjustment of the photochemical efficiency of undamaged PSI to the reduced rate of photochemistry in PSII.

Key words

Chlorophyll fluorescenceHeat stressLeaf (light absorbance)PhotoprotectionPhotosystem I, IIPisum (photosynthesis)


B1 and B2

fraction of closed PSI and PSII reaction centers, respectively


photoacoustically measured energy storage

Fo, Fm and Fs

initial, maximal and steady-state levels of chlorophyll fluorescence


reaction center of PSI

PS (I, II)

photosystem (I, II)

V = (Fs − Fo)/(Fm − Fo)

relative variable chlorophyll fluorescence

Copyright information

© Springer-Verlag 1991

Authors and Affiliations

  • Michel Havaux
    • 1
  • Hubert Greppin
    • 2
  • Reto J. Strasser
    • 1
  1. 1.Laboratoire de BioénergétiqueUniversité de GenèveLullier-Genève
  2. 2.Laboratoire de Biochimie et physiologie végétalesUniversité de GenèveGenève 4Switzerland
  3. 3.DPVE, CEN CadaracheSaint-Paul-Lez-DuranceFrance