Non-photochemical quenching of chlorophyll a fluorescence in isolated chloroplasts under conditions of stressed photosynthesis

✍ Scribed by Henrik Laasch

• Publisher: Springer-Verlag
• Year: 1987
• Tongue: English
• Weight: 699 KB
• Volume: 171
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00391097

✦ Synopsis

Non-photochemical quenching of chlorophyll a fluorescence after short-time light, heat and osmotic stress was investigated with intact chloroplasts from Spinacia oleracea L. The proportions of non-photochemial fluorescence quenching (qN) which are related (q~) and unrelated (qi) to the transthylakoid proton gradient (3 pH) were determined. Light stress resulted in an increasing contribution of qr to total qN-The linear dependence of qE and 3pH, as seen in controls, was maintained. The mechanisms underlying this type of quenching are obviously unaffected by photoinhibition. In constrast, q~ was severely affected by heat and osmotic stress. In low light, the response of qE to changes in 3pH was enhanced, whereas it was reduced in high light. The data are discussed with reference to the hypothesis that qE is related to thermal dissipation of excitation energy from photosystem II. It is shown that qE is not only controlled by 3 pH, but also by external factors.