, Volume 198, Issue 3, pp 385-396

Isolation of high-chlorophyll-fluorescence mutants ofArabidopsis thaliana and their characterisation by spectroscopy, immunoblotting and Northern hybridisation

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Abstract

Thirty-four recessive photosynthetic mutants of the high-chlorophyll-fluorescence (hcf) phenotype have been isolated by screening 7700 M2 progenies of ethyl methane sulfonate-treated seeds ofArabidopsis thaliana. Most of the mutants isolated were found to be seedlinglethal, but could be grown on sucrose-supplemented media. Chlorophyll (Chl) fluorescence induction, absorption changes in the reaction-centre chlorophyll of PS I (P700) at 830 nm and Chla/Chlb ratios were recorded in order to probe the photosynthetic functions and to define the mutational lesion. These studies were complemented by immunoblot and Northern analyses which finally led to the classification of the mutants into six different groups. Four classes of mutants were affected in PS I, PS II (two different classes) or the intersystem electron-transport chain, respectively. A fifth mutant class was of pleiotropic nature and the sixth class comprised a Chlb-deficient mutant. Several of the mutants showed severe deficiencies in the levels of subunits of PS I, PS II or the cytochromeb 6/f complex. Thus the mutational lesions could be located precisely. Only one mutant was defective in the transcript patterns of some plastid-encoded photosynthesis genes. Hence most of the mutants isolated appear to be affected in translational and post-translational regulatory processes of thylakoid membrane biogenesis or in structural genes encoding constituent subunits of the thylakoid protein complexes.

This work was supported by grants from the Deutsche Forschungs-gemeinschaft (SFB 189) and the Fonds der Chemischen Industrie. We are very grateful to W. Rogmann and coworkers for the careful cultivation of the plants in the greenhouse. We thank Dr. P. Jahns (Institut für Biochemie der Pflanzen, Universität Düsseldorf, Germany) for the critical reading of the manuscript. Parts of this work have been submitted for the doctoral theses of Dr. K. Meierhoff and J. Meurer.