Wildtype and mutant plants were were grown under a 16-hr day regime, harvested at 3 weeks, and chloroplasts isolated. For freeze fracture, isolated chloroplasts were made 30% in glycerol, plunge frozen, and cleaved, etched, and shadowed in a Balzers freeze-fracture unit. Replicas were examined with a Philips 300 transmission EM and images recorded on film. See Fig 3 in KR Miller et al. 1976 J. Cell Biol 71, 624-638.