title: Functionally divergent alleles and duplicated Loci encoding an acyltransferase contribute to acylsugar metabolite diversity in Solanum trichomes.
abstract: Glandular trichomes from tomato (Solanum lycopersicum) and other species in the Solanaceae produce and secrete a mixture of O-acylsugars (aliphatic esters of sucrose and glucose) that contribute to insect defense. Despite their phylogenetic distribution and diversity, relatively little is known about how these specialized metabolites are synthesized. Mass spectrometric profiling of acylsugars in the S. lycopersicum x Solanum pennellii introgression lines identified a chromosome 11 locus containing a cluster of BAHD acyltransferases with one gene (named Sl-ASAT3) expressed in tip cells of type I trichomes where acylsugars are made. Sl-ASAT3 was shown to encode an acyl-CoA-dependent acyltransferase that catalyzes the transfer of short (four to five carbons) branched acyl chains to the furanose ring of di-acylsucrose acceptors to produce tri-acylsucroses, which can be further acetylated by Sl-ASAT4 (previously Sl-AT2). Among the wild tomatoes, diversity in furanose ring acyl chains on acylsucroses was most striking in Solanum habrochaites. S. habrochaites accessions from Ecuador and northern Peru produced acylsucroses with short (≤C5) or no acyl chains on the furanose ring. Accessions from central and southern Peru had the ability to add short or long (up to C12) acyl chains to the furanose ring. Multiple ASAT3-like sequences were found in most accessions, and their in vitro activities correlated with observed geographical diversity in acylsugar profiles.
authors: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319 schilmil@msu.edu.
authors: Anthony L
authors: http://orcid.org/0000-0001-7069-7120
authors: AL
authors: Schilmiller
authors: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319.
authors: Gaurav D
authors: http://orcid.org/0000-0002-8761-064X
authors: GD
authors: Moghe
authors: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319.
authors: Pengxiang
authors: P
authors: Fan
authors: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319.
authors: Banibrata
authors: B
authors: Ghosh
authors: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319.
authors: Jing
authors: J
authors: Ning
authors: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319 Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1319.
authors: A Daniel
authors: http://orcid.org/0000-0002-7408-6690
authors: AD
authors: Jones
authors: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824-1319 Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824-1319.
authors: Robert L
authors: http://orcid.org/0000-0001-6974-9587
authors: RL
authors: Last
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D000483:Alleles; D013058:Mass Spectrometry; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D032322:Solanum / Q000201:enzymology* / Q000235:genetics
chemical_list: D010940:Plant Proteins; D000217:Acyltransferases