Isoprene emission rates under elevated CO2 and O3 in two field-grown aspen clones differing in their sensitivity to O3

Authors

  • Carlo Calfapietra,

    1. CNR- Istituto di Biologia Agroambientale e Forestale, Via Salaria Km. 29.300 00016 Monterotondo Scalo (Roma), Italy;
    2. University of Tuscia, Department of Forest Environment and Resources (DISAFRI), Via S.Camillo de Lellis snc, 01100 Viterbo, Italy;
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  • Giuseppe Scarascia Mugnozza,

    1. CNR- Istituto di Biologia Agroambientale e Forestale, Via Salaria Km. 29.300 00016 Monterotondo Scalo (Roma), Italy;
    2. University of Tuscia, Department of Forest Environment and Resources (DISAFRI), Via S.Camillo de Lellis snc, 01100 Viterbo, Italy;
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  • David F. Karnosky,

    1. School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA;
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  • Francesco Loreto,

    1. CNR- Istituto di Biologia Agroambientale e Forestale, Via Salaria Km. 29.300 00016 Monterotondo Scalo (Roma), Italy;
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  • Thomas D. Sharkey

    1. Michigan State University, 410 Biochemistry Building, East Lansing, MI 48824, USA
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Author for correspondence:
Carlo Calfapietra
Tel:+39 06 90672530
Fax:+39 06 9064492
Email: carlo.calfapietra@ibaf.cnr.it

Summary

  • • Isoprene is the most important nonmethane hydrocarbon emitted by plants. The role of isoprene in the plant is not entirely understood but there is evidence that it might have a protective role against different oxidative stresses originating from heat shock and/or exposure to ozone (O3). Thus, plants under stress conditions might benefit by constitutively high or by higher stress-induced isoprene emission rates.
  • • In this study, measurements are presented of isoprene emission from aspen (Populus tremuloides) trees grown in the field for several years under elevated CO2 and O3. Two aspen clones were investigated: the O3-tolerant 271 and the O3-sensitive 42E.
  • • Isoprene emission decreased significantly both under elevated CO2 and under elevated O3 in the O3-sensitive clone, but only slightly in the O3-tolerant clone.
  • • This study demonstrates that long-term-adapted plants are not able to respond to O3 stress by increasing their isoprene emission rates. However, O3-tolerant clones have the capacity to maintain higher amounts of isoprene emission. It is suggested that tolerance to O3 is explained by a combination of different factors; while the reduction of O3 uptake is likely to be the most important, the capacity to maintain higher amounts of isoprene is an important factor in strengthening this character.

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