Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6493282 | Journal of Photochemistry and Photobiology B: Biology | 2018 | 42 Pages |
Abstract
Salinity is one of the most important abiotic stress affecting plant growth and productivity worldwide. Photosynthesis, together with cell growth, is among the primary process affected by salinity. Here, we report the effects of salt stress on photosynthesis in the model halophyte Thellungiella salsuginea. Plants were grown in hydroponic system and then treated for 2â¯weeks with different NaCl concentrations (0, 100, 200 and 400â¯mM). Leaf analysis using both photonic and transmission electron microscopes showed some changes in mesophyll cell organization, including shape and dimension. Under high NaCl concentration (400â¯mM) a swelling of thylakoids and starch accumulation was also observed. The obtained results also showed a change in the photosynthetic efficiency of both photosystems (PSI and PSII), depending on both NaCl concentrations and duration of the stress treatment. Under moderate salinity (100 and 200â¯mM NaCl) no significant variation was observed in PSI and PSII yield parameters. Chlorophyll a fluorescence transient showed some variations in OJ, JI and IP phases under salt stress depending also on NaCl levels and the duration of stress. Under high salinity PSII donor side was affected as well as quantum yield of PSI which also showed a donor side limitation. A significant decrease on quantum yields Y(I) and Y(II) under high salt treatment (400â¯mM NaCl) for prolonged period of time (15â¯days) was observed. The decrease of these parameters was quantitatively compensated by a corresponding increase of energy thermal dissipation Y(NPQ) in photosystem II and a increase in the Y(ND) in PSI. Analysis of derived parameters from the OJIP transient curve revealed that ABS/RC decreased under NaCl treatment by reason of the increase in size of antenna of active reaction centers. An increase in the performance index PI(ABS), a slight decrease in the rate of DIO/RC, TRO/RC and the level of electron transport per PSII RC (ETO/RC) were observed during the first days of salt stress treatment reflecting a high PSII efficiency.
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Authors
Rahma Goussi, Arafet Manaa, Walid Derbali, Simone Cantamessa, Chedly Abdelly, Roberto Barbato,