Arabitol provided by lichenous fungi enhances ability to dissipate excess light energy in a symbiotic green alga under desiccation

Makiko Kosugi, Hirohisa Miyake, Hisanori Yamakawa, Yutaka Shibata, Atsuo Miyazawa, Takashi Sugimura, Kazuhiko Satoh, Shigeru Itoh, Yasuhiro Kashino

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Lichens are drought-resistant symbiotic organisms of mycobiont fungi and photobiont green algae or cyanobacteria, and have an efficient mechanism to dissipate excess captured light energy into heat in a picosecond time range to avoid photoinhibition. This mechanism can be assessed as drought-induced non-photochemical quenching (d-NPQ) using time-resolved fluorescence spectroscopy. A green alga Trebouxia sp., which lives within a lichen Ramalina yasudae, is one of the most common green algal photobionts. This alga showed very efficient d-NPQ under desiccation within the lichen thallus, whereas it lost d-NPQ ability when isolated from R. yasudae, indicating the importance of the interaction with the mycobiont for d-NPQ ability. We analyzed the water extracts from lichen thalli that enhanced d-NPQ in Trebouxia. Of several sugar compounds identified in the water extracts by nuclear magnetic resonance (NMR), mass spectrometry (MS) and gas chromatography (GC) analyses, only d-arabitol recovered d-NPQ in isolated Trebouxia to a level similar to that detected for R. yasudae thallus. Other sugar compounds did not help the expression of d-NPQ at the same concentrations. Thus, arabitol is essential for the expression of d-NPQ to dissipate excess captured light energy into heat, protecting the photobiont from photoinhibition. The relationship between mycobionts and photobionts is, therefore, not commensalism, but mutualism with each other, as shown by d-NPQ expression.

Original languageEnglish
Pages (from-to)1316-1325
Number of pages10
JournalPlant and Cell Physiology
Volume54
Issue number8
DOIs
Publication statusPublished - 2013 Aug 19

Keywords

  • Chl fluorescence
  • Drought tolerance
  • Lichen
  • NPQ
  • Non-photochemical quenching
  • Photoinhibition

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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