Some effects of 4-chloro-5-(dimethylamino)-2-phenyl-3(2H)-pyridazinone (San 9785) on the development of chloroplast thylakoid membranes inHordeum vulgareL.
✍ Scribed by R. M. Leech; C. A. Walton; N. R. Baker
- Publisher
- Springer-Verlag
- Year
- 1985
- Tongue
- English
- Weight
- 761 KB
- Volume
- 165
- Category
- Article
- ISSN
- 0032-0935
No coin nor oath required. For personal study only.
✦ Synopsis
Chloroplast ultrastructural and photochemical features were examined in 6-d-old barley (Hordeum vulgate L. cv. Sundance) plants which had developed in the presence of 4-chloro-5-(dimethylamino)-2-phenyl-3 (2H)-pyridazinone (San 9785). In spite of a substantial modification of the fatty-acid composition of thylakoid lipids there were no gross abnormalities in chloroplast morphology, and normal amounts of membrane and chlorophyll were present. Fluorescence kinetics at 77 K demonstrated considerable energetic interaction of photosystem (PS)I and PSII chlorophylls within the altered lipid environment. An interference with electron transport was indicated from altered room-temperature fluorescence kinetics at 20~ Subtle changes in the arrangements of chloroplast membranes were consistently evident and the overall effect of these changes was to increase the proportion of appressed to nonappressed membranes. This correlated with a lower chlorophyll a/b ratio, an increase in the amount of light-harvesting chlorophylls as determined by gel electrophoresis and fluorescence emission spectra, and an increase in excitation-energy transfer from PSII to PSI, as predicted from current ideas on the organisation of photosystems in appressed and non-appressed thylakoid membranes.