Discrepancy in photosynthetic responses of the red alga Pyropia yezoensis to dehydration stresses under exposure to desiccation, high salinity, and high mannitol concentration

• DOI: 10.1007/s42995-021-00115-w
• Publication Date: 2021-11-25T11:06:37Z
• Authors: Guoying Du; Xiaojiao Li; Junhao Wang; Shuai Che; Xuefeng Zhong; Yunxiang Mao
• Keywords: Thallus

Macroalgae that inhabit intertidal zones are exposed to the air for several hours during low tide and must endure desiccation high variations in temperature, light intensity, salinity. Pyropia yezoensis (Rhodophyta, Bangiales), a typical red macroalga is commercially cultivated northwestern Pacific Ocean, was investigated under different dehydration stresses of desiccation, salinity, mannitol concentration. Using chlorophyll fluorescence imaging, photosynthetic activities P. thalli were analyzed using six parameters derived from quenching curves rapid curves. A distinct discrepancy revealed responses stresses. Dehydration caused by exposure resulted decreases activities, which always lower than two other at same water loss (WL) level. High salinity only reduced photosynthesis significantly its maximum WL 40% but maintained relatively stable quantum yield photosystem II (PSII) (Fv/Fm). concentration induced 20% longer time (60 min) treatments no adverse influences on except significant decrease non-photochemical (NPQ) WL. Illustrated images, severe spatial heterogeneities with values upper parts middle or basal thalli. The NPQ rETRmax (maximum relative electron transport rate) demonstrated clear distinctions evaluating responses, indicating their sensitivity applicability. findings this study indicated natural results stronger more heterogeneous effects those