Does leaf photosynthesis adapt to CO2-enriched environments? An experiment on plants originating from three natural CO2 springs

Authors

  • Yusuke Onoda,

    1. Graduate School of Life Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan;
    2. Present address: Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia
    Search for more papers by this author
  • Tadaki Hirose,

    1. Graduate School of Life Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan;
    2. Department of International Agriculture Development, Tokyo University of Agriculture, Sakuragaoka 1-1-1, Setagaya, Tokyo 156-8502, Japan;
    Search for more papers by this author
  • Kouki Hikosaka

    1. Graduate School of Life Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan;
    Search for more papers by this author

Author for correspondence:
Yusuke Onoda
Tel: +61 2 98506270
Email: yonoda@bio.mq.edu.au

Summary

  • • Atmospheric CO2 elevation may act as a selective agent, which consequently may alter plant traits in the future. We investigated the adaptation to high CO2 using transplant experiments with plants originating from natural CO2 springs and from respective control sites.
  • • We tested three hypotheses for adaptation to high-CO2 conditions: a higher photosynthetic nitrogen use efficiency (PNUE); a higher photosynthetic water use efficiency (WUE); and a higher capacity for carbohydrate transport from leaves.
  • • Although elevated growth CO2 enhanced both PNUE and WUE, there was no genotypic improvement in PNUE. However, some spring plants had a higher WUE, as a result of a significant reduction in stomatal conductance, and also a lower starch concentration. Higher natural variation (assessed by the coefficient of variation) within populations in WUE and starch concentration, compared with PNUE, might be responsible for the observed population differentiation.
  • • These results support the concept that atmospheric CO2 elevation can act as a selective agent on some plant traits in natural plant communities. Reduced stomatal conductance and reduced starch accumulation are highlighted for possible adaptation to high CO2.

Ancillary