AsianScientist (Nov. 1, 2018) – An international team of scientists has discovered that plants save energy in the dark by regulating the levels of transport proteins on chloroplasts, the organelles which allow plants to photosynthesize. The study was published in the Proceedings of the National Academy of Sciences.
Photosynthesis is the most important energy-harvesting process on our planet, and the molecule adenosine triphosphate (ATP) provides the energy needed for carbon fixation. Previously, researchers thought that the chloroplasts of plants import ATP from the cell’s cytosol to support carbon fixation during the day.
In the present study, a team of researchers from Hong Kong, Germany, Sweden and the US used a fluorescent protein sensor in the model plant (Arabidopsis thaliana) to detect ATP levels in chloroplasts and the cytosol in real time. Their observations indicate that although the chloroplast is the key energy harvester and producer in a plant cell, its demand for ATP is also extremely high.
They further reported that mature plant chloroplasts manage their ATP largely in isolation from other cellular spaces, and that ATP transporters on the chloroplast membrane are only expressed in the leaves of young plants.
“During their early developmental stage, young chloroplasts require exogenous ATP for biogenesis. When chloroplasts are fully developed and become self-sustainable, ATP transporters have to be downregulated so that the energy harvested in daytime would not be incontinently consumed by chloroplasts at night,” said study lead author Dr. Lim Boon Leong of HKU. “The primary job of mature leaf chloroplasts is to harvest energy and export sugar in the light to support the growth of the other cells, while minimizing its own wasteful energy consumption in the dark.”
Going forward, the team intends to explore how plant growth may be enhanced by modifying energy exchanges between chloroplasts and mitochondria.
The article can be found at: Voon et al. (2018) ATP Compartmentation in Plastids and Cytosol of Arabidopsis thaliana Revealed by Fluorescent Protein Sensing.
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Source: University of Hong Kong.
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