Abstract
A comparison of the effects of ionic stress and an uncoupler on long-term fluorescence transients (the 'Kautsky effect') in the green alga Dunaliella tertiolecta indicated that the large quenching induced by ionic stress was caused by a pH gradient across the thylakoid membrane. This possiblity was given support by the increase in the slow phase of 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea-induced fluorescence relaxation in algae subjected to ionic stress. Low-temperature fluorescence emission spectra indicated that salt stress enhanced photosystem-I emission in the dark, and a comparison of simultaneous emissions at 695 and 720 nm at room temperature indicated a further increase in photosystem-I emission during the fluorescence transients. Taken together with the decrease in the fast phase of 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea-induced fluorescence relaxation in stressed algae, our results indicate that ionic stress stimulates cyclic electron flow, and that non-cyclic flow is inhibited. The effect of sucrose-induced osmotic stress was similar to, but less marked than, the effects of NaCl and KCl; the effect of decreasing the external salinity was small.
Original language | English (US) |
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Pages (from-to) | 250-256 |
Number of pages | 7 |
Journal | Planta |
Volume | 163 |
Issue number | 2 |
DOIs | |
State | Published - Feb 1 1985 |
Externally published | Yes |
Keywords
- Chlorophyll fluorescence
- Dunaliella (osmoregulation)
- Osmoregulation
- Photosynthesis (ionic stress)
ASJC Scopus subject areas
- Genetics
- Plant Science