The effect of ionic stress on photosynthesis in Dunaliella tertiolecta - Chlorophyll fluorescence kinetics and spectral characteristics

D. J. Gilmour, M. F. Hipkins, A. N. Webber, N. R. Baker, A. D. Boney

Research output: Contribution to journalArticle

46 Scopus citations

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 languageEnglish (US)
Pages (from-to)250-256
Number of pages7
JournalPlanta
Volume163
Issue number2
DOIs
StatePublished - Feb 1 1985
Externally publishedYes

Keywords

  • Chlorophyll fluorescence
  • Dunaliella (osmoregulation)
  • Osmoregulation
  • Photosynthesis (ionic stress)

ASJC Scopus subject areas

  • Genetics
  • Plant Science

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