Mechanism of strong quenching of photosystem II chlorophyll fluorescence under drought stress in a lichen, Physciella melanchla, studied by subpicosecond fluorescence spectroscopy

Masayuki Komura, Atsushi Yamagishi, Yutaka Shibata, Ikuko Iwasaki, Shigeru Itoh

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

The mechanism of the severe quenching of chlorophyll (Chl) fluorescence under drought stress was studied in a lichen Physciella melanchla, which contains a photobiont green alga, Trebouxia sp., using a streak camera and a reflection-mode fluorescence up-conversion system. We detected a large 0.31 ps rise of fluorescence at 715 and 740 nm in the dry lichen suggesting the rapid energy influx to the 715-740 nm bands from the shorter-wavelength Chls with a small contribution from the internal conversion from Soret bands. The fluorescence, then, decayed with time constants of 23 and 112 ps, suggesting the rapid dissipation into heat through the quencher. The result confirms the accelerated 40 ps decay of fluorescence reported in another lichen (Veerman et al., 2007 [36]) and gives a direct evidence for the rapid energy transfer from bulk Chls to the longer-wavelength quencher. We simulated the entire PS II fluorescence kinetics by a global analysis and estimated the 20.2 ns-1 or 55.0 ns-1 energy transfer rate to the quencher that is connected either to the LHC II or to the PS II core antenna. The strong quenching with the 3-12 times higher rate compared to the reported NPQ rate, suggests the operation of a new type of quenching, such as the extreme case of Chl-aggregation in LHCII or a new type of quenching in PS II core antenna in dry lichens.

Original languageEnglish
Pages (from-to)331-338
Number of pages8
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1797
Issue number3
DOIs
Publication statusPublished - 2010 Mar

Keywords

  • Chlorophyll fluorescence
  • Drought stress
  • Excitation energy transfer
  • Fluorescence quenching
  • Lichen
  • Photosynthesis
  • Photosystem II
  • Up-conversion spectroscopy

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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