Response of linear and cyclic electron flux to moderate high temperature and high light stress in tomato

• Published in: Journal of Zhejiang University. B. Science 2017-07, Vol.18 (7), p.635-648
• Main Authors: Lu, Tao, Shi, Jie-wei, Sun, Zhou-ping, Qi, Ming-fang, Liu, Yu-feng, Li, Tian-lai
• Format: Article
• Language: English
• Subjects: Adenosine triphosphatase; Adenosine Triphosphatases - metabolism; Biomedical and Life Sciences; Biomedicine; Chlorophyll - metabolism; Distilled water; Diuron; Electron density; Electron Transport; Electrons; Energy; Energy absorption; Energy conversion; Energy conversion efficiency; Energy distribution; Excitation; Fluorescence; High temperature; Hot Temperature; Hydrogen-Ion Concentration; Inhibitors; Integrity; Light; Lycopersicon esculentum - physiology; Lycopersicon esculentum - radiation effects; Methyl viologen; Photochemical reactions; Photochemicals; Photoinhibition; Photosynthesis; Photosystem I; Photosystem I Protein Complex - metabolism; Photosystem II; Plant Leaves - physiology; Plant Leaves - radiation effects; Protonmotive force; Quantum efficiency; Seedlings; Seedlings - physiology; Seedlings - radiation effects; Stress; Stresses; Thylakoids - metabolism; Time Factors; Tomatoes
• ISSN: 1673-1581; 1862-1783
• DOI: 10.1631/jzus.B1600286

Objectives To evaluate the possible photoprotection mechanisms of cyclic and linear electron flux (CEF and LEF) under specific high temperature and high light (HH) stress. Methods Six-leaf-stage tomato seedlings (“Liaoyuanduoli”, n =160) were divided into four parts: Part 1, served as control under 25 °C, 500 μmol/(m 2 ·s); Part 2, spayed with distilled water (H 2 O) under 35 °C, 1000 μmol/(m 2 ·s) (HH); Part 3, spayed with 100 μmol/L diuron (DCMU, CEF inhibitor) under HH; Part 4, spayed with 60 μmol/L methyl viologen (MV, LEF inhibitor) under HH. Energy conversion, photosystem I (PSI), and PSII activity, and trans -thylakoid membrane proton motive force were monitored during the treatment of 5 d and of the recovering 10 d. Results HH decreased photochemical reaction dissipation ( P ) and the maximal photochemical efficiency of PSII ( F v / F m ), and increased the excitation energy distribution coefficient of PSII ( β ); DCMU and MV aggravated the partition imbalance of the excitation energy ( γ ) and the photoinhibition degree. With prolonged DCMU treatment time, electron transport rate and quantum efficiency of PSI (ETR I and Y I ) significantly decreased whereas acceptor and donor side limitation of PSI ( Y NA and Y ND ) increased. MV led to a significant decline and accession of yield of regulated and non-regulated energy Y NPQ and Y NO , respectively. Membrane integrity and ATPase activity were reduced by HH stress, and DCMU and MV enhanced inhibitory actions. Conclusion The protective effects of CEF and LEF were mediated to a certain degree by meliorations in energy absorption and distribution as well as by maintenance of thylakoid membrane integrity and ATPase activity.