J Integr Plant Biol. ›› 1974, Vol. 16 ›› Issue (4): -.

• Research Articles •    

Studies on the Electron Transport of Photosystem II of Photosynthesis

6th Laboratory of Peking Institute of Botany, Academia Sinica   

Abstract: In spinach chloroplasts and PSⅡ particles, photoreduction of DCIP and of FeCy (ferricyanide) respond differently to inhibition by DCMU or by Tris-washing. The effects are pH (Tris) and concentration (DCMU) dependent. At pH 8, DCIP photoreduction by chloroplasts and PSⅡ particles were inhibited completely by Tris-washing (0.8 M), while a small amount of residual FeCy photoreduction still remained. In normal chloroplasts, at DCMU concentrations of 5 × 10-5 and 5 × 10-4 M, DCIP photoreduction was completely lost, while photoreduction of FeCy remained at about 11.5%. With Tris-washed chloroplasts, when photoreduction of DCIP was completely abolished by 5 × 10-6 M, 5 × 10-5 M and 5 × 10-4 M DCMU, FeCy photoreduction still remained at 14.1%, 15.0% and 13.5% respectively. When comparied with that of the control. In normal PSⅡ particles, DCIP photoreduction was completely inhibited by DCMU at concentrations of 5 × 10-6 M and 5 × 10-5 M, while they still retained a residual FeCy photoreduction of 13.8% and 11.7% respectively. With Tris-washed (pH 7.6, 0.8 M) PSⅡ particles, the residual FeCy photoreduction was 26.2% and 19.2% at DCMU concentrations of 5 × 10-7 and 5 × 10-6 M respectively, while the DCIP photoreduction was completely inhibited. Activity of the residual FeCy photoreduction by Tris-washed or DCMU treated chloroplasts and PS-Ⅱ particles is higher at short wavelength light (651μm) than at longer wavelength light (714 μm). The possible involvement of two short-wavelength light reactions in PSⅡ is discussed.

Editorial Office, Journal of Integrative Plant Biology, Institute of Botany, CAS
No. 20 Nanxincun, Xiangshan, Beijing 100093, China
Tel: +86 10 6283 6133 Fax: +86 10 8259 2636 E-mail: jipb@ibcas.ac.cn
Copyright © 2022 by the Institute of Botany, the Chinese Academy of Sciences
Online ISSN: 1744-7909 Print ISSN: 1672-9072 CN: 11-5067/Q