Identical substitutions in nagnesium chelatase paralogs result in chlorophyll-deficient soybean mutants

Benjamin W. Campbell, Dhananjay Mani, Shaun J. Curtin, Rebecca A. Slattery, Jean Michel Michno, Donald R. Ort, Philip J. Schaus, Reid G. Palmer, James H. Orf, Robert M. Stupar

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49 Scopus citations


The soybean [Glycine max (L.) Merr.] chlorophyll-deficient line MinnGold is a spontaneous mutant characterized by yellow foliage. Map-based cloning and transgenic complementation revealed that the mutant phenotype is caused by a nonsynonymous nucleotide substitution in the third exon of a Mg-chelatase subunit gene (ChlI1a) on chromosome 13. This gene was selected as a candidate for a different yellow foliage mutant, T219H (Y11y11), that had been previously mapped to chromosome 13. Although the phenotypes of MinnGold and T219H are clearly distinct, sequencing of ChlI1a in T219H identified a different nonsynonymous mutation in the third exon, only six base pairs from the MinnGold mutation. This information, along with previously published allelic tests, were used to identify and clone a third yellow foliage mutation, CD-5, which was previously mapped to chromosome 15. This mutation was identified in the ChlI1b gene, a paralog of ChlI1a. Sequencing of the ChlI1b allele in CD-5 identified a nonsynonymous substitution in the third exon that confers an identical amino acid change as the T219H substitution at ChlI1a. Protein sequence alignments of the two Mg-chelatase subunits indicated that the sites of amino acid modification in MinnGold, T219H, and CD-5 are highly conserved among photosynthetic species. These results suggest that amino acid alterations in this critical domain may create competitive inhibitory interactions between the mutant and wild-type ChlI1a and ChlI1b proteins.

Original languageEnglish (US)
Pages (from-to)123-131
Number of pages9
JournalG3: Genes, Genomes, Genetics
Issue number1
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© 2015 Campbell et al.


  • Chlorophyll
  • Duplication
  • Paralog
  • Photosynthesis
  • Soybean


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