Molecular cloning of a maize gene involved in photosynthetic membrane organization that is regulated by Robertson's Mutator

The maize photosynthetic mutant hcf106 has a distinctive and unusual thylakoid membrane organization, and fails to accumulate three of the five thylakoid membrane protein complexes. This mutant arose in a Robertson's Mutator background, and shows somatic instability typical of a transposon-induced allele. In addition, hcf106 is suppressed when Mu1 elements are inactive and modified in their terminal inverted repeats. Thus plants homozygous for the mutant allele adopt a mutant phenotype only when Mu1 elements are active and unmodified. DNA from the mutant allele has been cloned by 'transposon-tagging' using the transposon Mu1, and the identity of the clone confirmed by observing somatic excision of the transposon in a revertant sector. A 1.2 kb transcript homologous to the cloned DNA is found in wild-type and suppressed seedlings, but is not found in mutant seedlings, suggesting that suppression is mediated at the level of transcript accumulation.