Chronic effects of three different stressors, irradiance, temperature, and desiccation, on the PSII photochemical effici
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Chronic effects of three different stressors, irradiance, temperature, and desiccation, on the PSII photochemical efficiency in the heteromorphic life-history stages of cultivated Pyropia yezoensis f. narawaensis (Bangiales) from Japan Ryuta Terada 1
&
Tomohiro Yuge 2 & Yuki Watanabe 3 & Takayuki Mine 4 & Tarou Morikawa 4 & Gregory N. Nishihara 5
Received: 30 December 2019 / Revised and accepted: 5 May 2020 # Springer Nature B.V. 2020
Abstract The chronic effects of three different stressors, irradiance, temperature, and desiccation, on Photosystem II (PSII) photochemical efficiency were investigated in two heteromorphic life-history stages of a cultivated red alga, Pyropia yezoensis f. narawaensis (Bangiales) from Japan. The maximum quantum yields of PSII (Fv/Fm) over the range of temperature between 4 and 36 °C for 96h exposure showed different responses in the two life-history stages. In the macroscopic gametophyte, the highest value (0.47) occurred at 12.0 °C; however, Fv/Fm quickly decreased at higher temperatures. In contrast, Fv/Fm in the microscopic sporophyte were less sensitive to temperature, suggesting adaptation to the broad range of temperature with a high value (0.40) that occurred at 21.1 °C. Continuous 6-h exposures to the 50, 100, and 1000 μmol photons m−2 s−1 revealed greater decline in their effective quantum yields of PSII (ΔF/Fm′) in the sporophyte. As known in the photoprotective response and its PSII repair system in the photosynthesis, the recovery of quantum yield in two life-history stages after subsequent acclimation (darkness and dim-light treatments) was more accelerated in dim-light than those of darkness. The response to continuous desiccation (240-min aerial exposure) in two life-history stages was also different, and the ΔF/Fm′ in the gametophyte returned to initial values after reimmersion in seawater. In contrast, those in the sporophyte dropped to zero after a 5-min aerial exposure and did not return to initial values, suggesting that farming protocols for the conchospore seeding in Nori-net cultivation need to pay careful attention to desiccation to ensure successful production. Keywords Algae . Desiccation tolerance . Nori . PSII photochemical efficiency . Photoinhibition . Pulse amplitude-modulation (PAM)-chlorophyll fluorometry . Porphyra . Pyropia
Introduction
* Ryuta Terada [email protected] 1
United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890-0065, Japan
2
Faculty of Fisheries, Kagoshima University, Kagoshima 890-0056, Japan
3
Central Laboratory, Marine Ecology Research Institute, Onjuku, Chiba 299-5105, Japan
4
Saga Prefectural Ariake Fisheries Research and Development Center (SAFREDEC), Ogi, Saga 849-0313, Japan
5
Institute for East China Sea Research, Organization for Marine Science and Technology, Nagasaki University, Nagasaki 851-2213, Japan
The red algal genus Pyropia (Porphyra sensu lato; Sutherland et al. 2011; Bangiaceae, Bangiales) is known as a major source of Nori production in East Asian countries,
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