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

作　　者：Guoying Du Xiaojiao Li Junhao Wang Shuai Che Xuefeng Zhong Yunxiang Mao 

机构地区：[1]Key Laboratory of Marine Genetics and Breeding(Ministry of Education),College of Marine Life Sciences,Ocean University of China,Qingdao,266003,China [2]Qingdao West Coast New Area Marine Development Bureau,Qingdao,266003,China [3]Key Laboratory of Utilization and Conservation of Tropical Marine Bioresource(Ministry of Education),College of Fisheries and Life Science,Hainan Tropical Ocean University,Sanya,572022,China

出　　处：《Marine Life Science & Technology》2022年第1期10-17,共8页海洋生命科学与技术（英文）

基　　金：supported by National Key R&D Program of China(2018YFC1406704 and 2020YFD0900702).

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

关 键 词：Dehydration stress DESICCATION High salinity High mannitol concentration Photosynthetic activities Pyropia yezoensis 

分 类 号：Q94[生物学—植物学]