title: Gene expression and metabolism in tomato fruit surface tissues.
abstract: The cuticle, covering the surface of all primary plant organs, plays important roles in plant development and protection against the biotic and abiotic environment. In contrast to vegetative organs, very little molecular information has been obtained regarding the surfaces of reproductive organs such as fleshy fruit. To broaden our knowledge related to fruit surface, comparative transcriptome and metabolome analyses were carried out on peel and flesh tissues during tomato (Solanum lycopersicum) fruit development. Out of 574 peel-associated transcripts, 17% were classified as putatively belonging to metabolic pathways generating cuticular components, such as wax, cutin, and phenylpropanoids. Orthologs of the Arabidopsis (Arabidopsis thaliana) SHINE2 and MIXTA-LIKE regulatory factors, activating cutin and wax biosynthesis and fruit epidermal cell differentiation, respectively, were also predominantly expressed in the peel. Ultra-performance liquid chromatography coupled to a quadrupole time-of-flight mass spectrometer and gas chromatography-mass spectrometry using a flame ionization detector identified 100 metabolites that are enriched in the peel tissue during development. These included flavonoids, glycoalkaloids, and amyrin-type pentacyclic triterpenoids as well as polar metabolites associated with cuticle and cell wall metabolism and protection against photooxidative stress. Combined results at both transcript and metabolite levels revealed that the formation of cuticular lipids precedes phenylpropanoid and flavonoid biosynthesis. Expression patterns of reporter genes driven by the upstream region of the wax-associated SlCER6 gene indicated progressive activity of this wax biosynthetic gene in both fruit exocarp and endocarp. Peel-associated genes identified in our study, together with comparative analysis of genes enriched in surface tissues of various other plant species, establish a springboard for future investigations of plant surface biology.
authors.affiliation: Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Shira
authors.initials: S
authors.lastname: Mintz-Oron
authors.forename: Tali
authors.initials: T
authors.lastname: Mandel
authors.forename: Ilana
authors.initials: I
authors.lastname: Rogachev
authors.forename: Liron
authors.initials: L
authors.lastname: Feldberg
authors.forename: Ofra
authors.initials: O
authors.lastname: Lotan
authors.forename: Merav
authors.initials: M
authors.lastname: Yativ
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Wang
authors.forename: Reinhard
authors.initials: R
authors.lastname: Jetter
authors.forename: Ilya
authors.initials: I
authors.lastname: Venger
authors.forename: Avital
authors.initials: A
authors.lastname: Adato
authors.forename: Asaph
authors.initials: A
authors.lastname: Aharoni
mesh_terms: D001483:Base Sequence; D002853:Chromatography, Liquid; D017931:DNA Primers; D008401:Gas Chromatography-Mass Spectrometry; D020869:Gene Expression Profiling; D017343:Genes, Plant; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry; D005810:Multigene Family; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D017931:DNA Primers