Single-cell C4 photosynthesis: efficiency and acclimation of Bienertia sinuspersici to growth under low light

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Summary

  • Traditionally, it was believed that C4 photosynthesis required two types of chlorenchyma cells to concentrate CO2 within the leaf. However, several species have been identified that perform C4 photosynthesis using dimorphic chloroplasts within an individual cell. The goal of this research was to determine how growth under limited light affects leaf structure, biochemistry and efficiency of the single-cell CO2-concentrating mechanism in Bienertia sinuspersici.
  • Measurements of rates of CO2 assimilation and CO2 isotope exchange in response to light intensity and O2 were used to determine the efficiency of the CO2-concentrating mechanism in plants grown under moderate and low light. In addition, enzyme assays, chlorophyll content and light microscopy of leaves were used to characterize acclimation to light-limited growth conditions.
  • There was acclimation to growth under low light with a decrease in capacity for photosynthesis when exposed to high light. This was associated with a decreased investment in biochemistry for carbon assimilation with only subtle changes in leaf structure and anatomy. The capture and assimilation of CO2 delivered by the C4 cycle was lower in low-light-grown plants.
  • Low-light-grown plants were able to acclimate to maintain structural and functional features for the performance of efficient single-cell C4 photosynthesis.

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