, Volume 182, Issue 4, pp 523–531

A gas-exchange study of photosynthesis and isoprene emission inQuercus rubra L.

  • Francesco Loreto
  • Thomas D. Sharkey


We have investigated the signals which affect the rate of isoprene emission from photosynthesizing leaves of red oak (Quercus rubra L.) using analytical gas-exchange techniques, chlorophyll-fluorescence measurements, and inhibitor feeding. Isoprene emission increased with increasing photon flux density at low CO2 but much less so at high CO2 partial pressure. Photosynthetic CO2 assimilation exhibited the opposite behavior. In CO2-free air, isoprene emission was reduced; above 500 μbar CO2 partial pressure, isoprene emission was also reduced. The high-CO2 effect appeared to be related to low ATP levels which can occur during feedback-limited photosynthesis. At high temperature, which can prevent feedback limitations, isoprene emission remained high as CO2 partial pressure was increased. After exposing the leaves to darkness, isoprene emission declined over 15 min, while photosynthesis stopped within 2 min. Adding far-red light to stimulate cyclic photo-phosphorylation during the post-illumination period stimulated isoprene emission. These analyses lead us to propose that the rate of isoprene emission is regulated by ATP. Analysis of transients indicated that isoprene emission is also related to photosynthetic carbon metabolism. Inhibitor feeding indicated that 3-phosphoglyceric acid and 1,3-bisphosphoglyceric acid are possible candidates for the link between photosynthetic carbon metabolism and the regulation of isoprene emission. Given the ATP dependence, we suggest that the concentration of 1,3-bisphosphoglyceric acid may exert control over the rate of isoprene emission from oak leaves.

Key words

ATP 1,3-Bisphosphoglycerate Gas exchange and isoprene Isoprene Photosynthetic carbon metabolism and isoprene Quercus 

Abbreviations and Symbols


photon flux density

qN, qP

nonphotochemical and photochemical, respectively, chlorophyll fluorescence quenching


ribulose 1,5-bisphosphate


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Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • Francesco Loreto
    • 1
  • Thomas D. Sharkey
    • 1
  1. 1.Department of BotanyUniversity of WisconsinMadisonUSA

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