Vol.:(0123456789) 1 3 Photosynth Res (2018) 136:229–243 DOI 10.1007/s11120-017-0461-0 ORIGINAL ARTICLE Red shift in the spectrum of a chlorophyll species is essential for the drought-induced dissipation of excess light energy in a poikilohydric moss, Bryum argenteum Yutaka Shibata 1  · Ahmed Mohamed 1,2  · Koichiro Taniyama 1  · Kentaro Kanatani 1  · Makiko Kosugi 3  · Hiroshi Fukumura 1,4   Received: 25 May 2017 / Accepted: 27 October 2017 / Published online: 9 November 2017 © Springer Science+Business Media B.V., part of Springer Nature 2017 in its quenched form. Two emission components at around 717 and 725 nm were assigned to photosystem I (PS I). The former component at around 717 nm is mildly quenched and probably bound to the PS I core complex, while the latter at around 725 nm is probably bound to the light-harvesting complex. The dehydration treatment caused a blue shift of the PS I emission peak via reduction of the exciton energy fow to the pigment responsible for the 725 nm band. Keywords Non-photochemical quenching · Chlorophyll-a · Chlorophyll-b · Streak camera · Decay- associated spectra · Target analysis Introduction The initial step of photosynthesis is the charge-separation reaction on the special chlorophyll (Chl) molecules excited by light. When the light intensity exceeds the capacity of the photosynthetic consumption, excessive excitations of Chls generate harmful species like reactive oxygen species (ROS) (Halliwell 1984; Demmig-Adams and Adams 2000; Munne- Bosch 2005). Therefore, plants have developed an ability to dissipate the excessive excitation energy to heat as well as to scavenge generated ROS (Nishiyama et al. 2006; Trianta- phylides and Havaux 2009). A typical example of the former mechanisms is the well-known non-photochemical quench- ing (NPQ) (Ruban 2016; Goss and Lepetit 2015), which dis- sipates the excessive light energy to heat depending on the activation of the xanthophyll cycle (Demmig-Adams 1990; Gilmore et al. 1995) and the protonation of a small protein, PsbS (Li et al. 2004; Takizawa et al. 2007). Since a water molecule is the primary electron donor, a lack of water causes severe stress to an oxygenic photo- synthetic organism. Actually, most higher plants cannot Abstract Some mosses are extremely tolerant of drought stress. Their high drought tolerance relies on their ability to efectively dissipate absorbed light energy to heat under dry conditions. The energy dissipation mechanism in a drought- tolerant moss, Bryum argenteum, has been investigated using low-temperature picosecond time-resolved fluorescence spectroscopy. The results are compared between moss thalli samples harvested in Antarctica and in Japan. Both samples show almost the same quenching properties, suggesting an identical drought tolerance mechanism for the same spe- cies with two completely diferent habitats. A global target analysis was applied to a large set of data on the fuores- cence-quenching dynamics for the 430-nm (chlorophyll-a selective) and 460-nm (chlorophyll-b and carotenoid selec- tive) excitations in the temperature region from 5 to 77 K. This analysis strongly suggested that the quencher is formed in the major peripheral antenna of photosystem II, whose emission spectrum is signifcantly broadened and red-shifted Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11120-017-0461-0) contains supplementary material, which is available to authorized users. * Yutaka Shibata shibata@m.tohoku.ac.jp 1 Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki Aza Aoba, Aoba-Ku, Sendai 980-8578, Japan 2 Present Address: Institut national de la recherche scientifque (INRS-EMT), Varennes, QC J3X 1S2, Canada 3 Department of Biological Science, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-Ku, Tokyo 112-8551, Japan 4 Present Address: National Institute of Technology, 4-16-1 Ayashi-chuo, Aoba-ku, Sendai 989-3128, Japan