Fig. 2.

Phenotype of tobacco plants with recombination-induced knockout of translation. (A) Segregating progeny of transplastomic RIKT plants. Variegated seedlings consist of both cells with translating and cells with nontranslating plastids whereas white seedlings have completely lost the spectinomycin-resistance gene by recombination and thus bleach out in the presence of the drug. (B) Close-up showing three seedlings with different degrees of variegation. (C) Phenotype of a RIKT plant on spectinomycin-containing synthetic medium. The arrow points to a leaf with half of the leaf blade missing. (D) Wild-type (left) and two RIKT (right) plants transferred from spectinomycin-containing synthetic medium to the soil. (E) The same plants after 3 weeks of growth in the soil. Note appearance of normal leaves in the RIKT plants in the absence of spectinomycin. (F) A RIKT plant transferred from spectinomycin-containing medium to drug-free medium. The lower leaves developed in the presence of the antibiotic (marked with filled arrows) whereas the upper leaves grew in the absence of spectinomycin (empty arrows) and gradually became more wild-type-like. (G) Reexposure of the same plant to spectinomycin-containing medium. Bleaching of leaf sectors in those leaves that developed in the absence of spectinomycin suggests that the these cell lines would have ceased to divide in the presence of the antibiotic and caused the phenotypic aberrations seen in leaves of RIKT plants. (H) Abnormal flower morphology in RIKT plants. The arrows point to missing sectors in the petals.