Alterations in Rubisco activity and in stomatal behavior induce a daily rhythm in photosynthesis of aerial leaves in the amphibious-plant Nuphar lutea

Ainit Snir, Michael Gurevitz, Yehouda Marcus*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Nuphar lutea is an amphibious plant with submerged and aerial foliage, which raises the question how do both leaf types perform photosynthetically in two different environments. We found that the aerial leaves function like terrestrial sun-leaves in that their photosynthetic capability was high and saturated under high irradiance (ca. 1,500 μmol photons m-2 s -1). We show that stomatal opening and Rubisco activity in these leaves co-limited photosynthesis at saturating irradiance fluctuating in a daily rhythm. In the morning, sunlight stimulated stomatal opening, Rubisco synthesis, and the neutralization of a night-accumulated Rubisco inhibitor. Consequently, the light-saturated quantum efficiency and rate of photosynthesis increased 10-fold by midday. During the afternoon, gradual closure of the stomata and a decrease in Rubisco content reduced the light-saturated photosynthetic rate. However, at limited irradiance, stomatal behavior and Rubisco content had only a marginal effect on the photosynthetic rate, which did not change during the day. In contrast to the aerial leaves, the photosynthesis rate of the submerged leaves, adapted to a shaded environment, was saturated under lower irradiance. The light-saturated quantum efficiency of these leaves was much lower and did not change during the day. Due to their low photosynthetic affinity for CO2 (35 μM) and inability to utilize other inorganic carbon species, their photosynthetic rate at air-equilibrated water was CO2-limited. These results reveal differences in the photosynthetic performance of the two types of Nuphar leaves and unravel how photosynthetic daily rhythm in the aerial leaves is controlled.

Original languageEnglish
Pages (from-to)233-242
Number of pages10
JournalPhotosynthesis Research
Volume90
Issue number3
DOIs
StatePublished - Dec 2006

Funding

FundersFunder number
G.I.F.
Israeli Science Foundation641/02
German-Israeli Foundation for Scientific Research and DevelopmentI-736-80.9/2002

    Keywords

    • Amphibious plant
    • Daily rhythm
    • Nuphar lutea (Nymphaceae)
    • Photosynthesis
    • Rubisco
    • Stomata behavior

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