A clover mutant lacking the chlorophyll a- and b-containing protein antenna complexes

A chlorophyll deficient mutant of clover has been examined by SDS-PAGE, spectrophotometric and electron microscopic methods. By a comparison of the absorption and first derivative spectra of acetone extracts from the mutant and normal biotypes, we observed a deficiency in chlorophyll b for the mutant biotype. The calculated chlorophyll a/b ratios, using the method of Arnon (Plant Physiol. 24, 1-15, 1949), approached infinity for the mutant whereas it ranged from 3.0-3.3 in the wild-type. The low temperature (77 degrees K) fluorescence emission bands in the 685-695 nm region could not be differentiated for the biotypes; however, the long wavelength emission band (near 740 nm in the wild-type) was shifted to shorter wavelengths (ca 720-725 nm) in the mutant indicating loss of photosystem I antenna. The SDS-PAGE profile of the mutant biotype showed a dramatic decline in the Coomassie stained polypeptides of apparent molecular weights similar to those of LHC II. Transmission electron micrographs of the mutant and normal tissue exhibited similar extents of grana-stacking, indicating that a component(s) other than the LHC II may be responsible for membrane adhesion in this mutant.