title: Analysis of natural and induced variation in tomato glandular trichome flavonoids identifies a gene not present in the reference genome.
abstract: Flavonoids are ubiquitous plant aromatic specialized metabolites found in a variety of cell types and organs. Methylated flavonoids are detected in secreting glandular trichomes of various Solanum species, including the cultivated tomato (Solanum lycopersicum). Inspection of the sequenced S. lycopersicum Heinz 1706 reference genome revealed a close homolog of Solanum habrochaites MOMT1 3'/5' myricetin O-methyltransferase gene, but this gene (Solyc06g083450) is missing the first exon, raising the question of whether cultivated tomato has a distinct 3' or 3'/5' O-methyltransferase. A combination of mining genome and cDNA sequences from wild tomato species and S. lycopersicum cultivar M82 led to the identification of Sl-MOMT4 as a 3' O-methyltransferase. In parallel, three independent ethyl methanesulfonate mutants in the S. lycopersicum cultivar M82 background were identified as having reduced amounts of di- and trimethylated myricetins and increased monomethylated myricetin. Consistent with the hypothesis that Sl-MOMT4 is a 3' O-methyltransferase gene, all three myricetin methylation defective mutants were found to have defects in MOMT4 sequence, transcript accumulation, or 3'-O-methyltransferase enzyme activity. Surprisingly, no MOMT4 sequence is found in the Heinz 1706 reference genome sequence, and this cultivar accumulates 3-methyl myricetin and is deficient in 3'-methyl myricetins, demonstrating variation in this gene among cultivated tomato varieties.
authors.affiliation: Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
authors.forename: Jeongwoon
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Matsuba
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824.
authors.forename: Jing
authors.initials: J
authors.lastname: Ning
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824.
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Schilmiller
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109.
authors.forename: Dagan
authors.initials: D
authors.lastname: Hammar
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 Department of Chemistry, Michigan State University, East Lansing, Michigan 48824.
authors.forename: A Daniel
authors.initials: AD
authors.lastname: Jones
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109.
authors.forename: Eran
authors.initials: E
authors.lastname: Pichersky
authors.affiliation: Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 lastr@msu.edu.
authors.forename: Robert L
authors.identifier: http://orcid.org/0000-0001-6974-9587
authors.initials: RL
authors.lastname: Last
mesh_terms: D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D005419:Flavonoids / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D014644:Genetic Variation; D018745:Genome, Plant; D018551:Solanum lycopersicum / Q000201:enzymology / Q000235:genetics*; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein
chemical_list: D005419:Flavonoids; D010940:Plant Proteins; D012333:RNA, Messenger; C040015:myricetin; D008780:Methyltransferases