Low temperature enhances photosynthetic down-regulation in French bean (Phaseolus vulgaris L.) plants

Tsonko Tsonev, Violeta Velikova, Katya Georgieva, Paul F. Hyde, Hamlyn Jones

    Research output: Contribution to journalArticle

    31 Citations (Scopus)

    Abstract

    The mechanisms of photosynthetic adaptation to different combinations of temperature and irradiance during growth, and especially the consequences of exposure to high light (2000 µmol m¯² s¯¹ PPFD) for 5 min, simulating natural sunflecks, was studied in bean plants (Phaseolus vulgaris L.). A protocol using only short (3 min) dark pre-treatment was introduced to maximize the amount of replication possible in studies of chlorophyll fluorescence. High light at low temperature (10 °C) significantly down-regulated photosynthetic electron transport capacity [as measured by the efficiency of photosystem II (PSII)], with the protective acclimation allowing the simulated sunflecks to be used more effectively for photosynthesis by plants grown in low light. The greater energy dissipation by thermal processes (lower Fv'/Fm' ratio) at low temperature was related to increased xanthophyll de-epoxidation and to the fact that photosynthetic carbon fixation was more limiting at low than at high temperatures. A key objective was to investigate the role of photorespiration in acclimation to irradiance and temperature by comparing the effect of normal (21 kPa) and low (1·5 kPa) O2 concentrations. Low [O2] decreased Fv/Fm and the efficiency of PSII (FPSII), related to greater PSII down-regulation in cold pre-treated plants, but minimized further inhibition by the mild ‘sunfleck’ treatment used. Results support the hypothesis that photorespiration provides a ‘safety-valve’ for excess energy.
    Original languageEnglish
    Pages (from-to)343-352
    Number of pages10
    JournalAnnals of Botany
    Volume91
    Issue number3
    DOIs
    Publication statusPublished - Feb 2003

      Fingerprint

    Keywords

    • Phaseolus vulgaris L.
    • Bean
    • Low temperature
    • Photosynthesis
    • Down-regulation
    • High light
    • Sunfleck
    • Chlorophyll fluorescence

    Cite this