Analysis of the Light-harvesting Pigment-Protein Complex of Wild Type and a Chlorophyll- b -less Mutant of Barley

Abstract

We have compared chloroplast lamellae isolated from a chlorophyll-bless mutant and wild type barley (Hordeum vulgare). The results demonstrate that: (a) one of the two major polypeptides comprising the lightharvesting complex (LHC) is present in the chlorophyll-b-less mutant; (b) higher cation concentrations are required to maintain grana stacks in the mutant; and (c) cation effects on excitation energy distribution are present in the chlorophyll-b-less mutant but are reduced in amount and are 'dependent on higher concentrations of cations. We interpret these data to support the concept that the LHC mediates cation-induced grana stacking and cation regulation of excitation energy distribution between photosystems I and II in chioroplast lamellae. A partial LHC complement in the mutant alters the quantitative cation requirement for both phenomena, but not the over-all qualitative response.