title: Positive correlation between PSI response and oxidative pentose phosphate pathway activity during salt stress in an intertidal macroalga.
abstract: Studies have demonstrated that photosynthetic limitations and starch degradation are responses to stress; however, the relationship between the two is seldom described in detail. In this article, the effects of salt stress on photosynthesis, the levels of NADPH and total RNA, the starch content and the activities of glucose-6-phosphate dehydrogenase (G6PDH) and ribulose-5-phosphate kinase (RPK) were evaluated. In thalli that underwent salt treatments, the cyclic electron flow through PSI showed greater stress tolerance than the flow through PSII. Even though the linear electron flow was suppressed by DCMU, the cyclic electron flow still operated. The electron transport rate I (ETRI) increased as the salinity increased when the thalli recovered in seawater containing DCMU. These results suggested that PSI receives electrons from a source other than PSII. Furthermore, the starch content and RPK activity decreased, while the content of NADPH and total RNA, and the activity of G6PDH increased under salt stress. Soluble sugar from starch degradation may enter the oxidative pentose phosphate pathway (OPPP) to produce NADPH and ribose 5-phosphate. Data analysis suggests that NADPH provides electrons for PSI in Ulva prolifera during salt stress, the OPPP participates in the stress response and total RNA is synthesized in excess to assist recovery.
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCollege of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Li
authors.initials: L
authors.lastname: Huan
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors.forename: Xiujun
authors.initials: X
authors.lastname: Xie
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCollege of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Zhenbing
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors.forename: Feifei
authors.initials: F
authors.lastname: Sun
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCollege of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Songcui
authors.initials: S
authors.lastname: Wu
authors.affiliation: Tianjin Key Laboratory of Marine Resources and Chemistry, College of Marine Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, China.
authors.forename: Moyang
authors.initials: M
authors.lastname: Li
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCollege of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Shan
authors.initials: S
authors.lastname: Gao
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaCollege of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Wenhui
authors.initials: W
authors.lastname: Gu
authors.affiliation: Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China gcwang@qdio.ac.cn.
authors.forename: Guangce
authors.initials: G
authors.lastname: Wang
mesh_terms: D002241:Carbohydrates / Q000032:analysis; D004579:Electron Transport; D009249:NADP / Q000378:metabolism*; D010427:Pentose Phosphate Pathway / Q000502:physiology*; D010788:Photosynthesis / Q000502:physiology; D045331:Photosystem I Protein Complex / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D054712:Salinity; D012492:Salts; D013213:Starch / Q000032:analysis; D013312:Stress, Physiological; D044445:Ulva / Q000235:genetics / Q000502:physiology*
chemical_list: D002241:Carbohydrates; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D012492:Salts; D009249:NADP; D013213:Starch
keywords: NADPH; OPPP; Photosynthesis; Salt stress; Starch