title: Identical substitutions in magnesium chelatase paralogs result in chlorophyll-deficient soybean mutants.
abstract: 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.
authors.affiliation: Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108.
authors.forename: Benjamin W
authors.initials: BW
authors.lastname: Campbell
authors.affiliation: Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108.
authors.forename: Dhananjay
authors.initials: D
authors.lastname: Mani
authors.affiliation: Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108.
authors.forename: Shaun J
authors.initials: SJ
authors.lastname: Curtin
authors.affiliation: Department of Plant Biology, University of Illinois, Urbana, Illinois 61801.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Slattery
authors.affiliation: Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Michno
authors.affiliation: Department of Plant Biology, University of Illinois, Urbana, Illinois 61801 US Department of Agriculture/Agricultural Research Service, Global Change and Photosynthesis Research Unit, Urbana, Illinois 61801.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Ort
authors.affiliation: Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Schaus
authors.affiliation: Department of Agronomy, Iowa State University, Ames, Iowa 50011.
authors.forename: Reid G
authors.initials: RG
authors.lastname: Palmer
authors.affiliation: Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108.
authors.forename: James H
authors.initials: JH
authors.lastname: Orf
authors.affiliation: Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108 rstupar@umn.edu.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Stupar
mesh_terms: D000595:Amino Acid Sequence; D002734:Chlorophyll / Q000172:deficiency*; D008190:Lyases / Q000235:genetics*; D009154:Mutation; D018515:Plant Leaves; D021122:Protein Subunits / Q000235:genetics; D013025:Glycine max / Q000235:genetics*
chemical_list: D021122:Protein Subunits; D002734:Chlorophyll; D008190:Lyases; C086788:magnesium chelatase
keywords: chlorophyll; duplication; paralog; photosynthesis; soybean