title: Metabolic and Molecular Changes of the Phenylpropanoid Pathway in Tomato (Solanum lycopersicum) Lines Carrying DifferentSolanum pennelliiWild Chromosomal Regions.
abstract: Solanum lycopersicumrepresents an important dietary source of bioactive compounds including the antioxidants flavonoids and phenolic acids. We previously identified two genotypes (IL7-3 and IL12-4) carrying loci from the wild speciesSolanum pennellii, which increased antioxidants in the fruit. Successively, these lines were crossed and two genotypes carrying both introgressions at the homozygous condition (DHO88 and DHO88-SL) were selected. The amount of total antioxidant compounds was increased in DHOs compared to both ILs and the control genotype M82. In order to understand the genetic mechanisms underlying the positive interaction between the two wild regions pyramided in DHO genotypes, detailed analyses of the metabolites accumulated in the fruit were carried out by colorimetric methods and LC/MS/MS. These analyses evidenced a lower content of flavonoids in DHOs and in ILs, compared to M82. By contrast, in the DHOs the relative content of phenolic acids increased, particularly the fraction of hexoses, thus evidencing a redirection of the phenylpropanoid flux toward the biosynthesis of phenolic acid glycosides in these genotypes. In addition, the line DHO88 exhibited a lower content of free phenolic acids compared to M82. Interestingly, the two DHOs analyzed differ in the size of the wild region on chromosome 12. Genes mapping in the introgression regions were further investigated. Several genes of the phenylpropanoid biosynthetic pathway were identified, such as one4-coumarate:CoA ligaseand twoUDP-glycosyltransferasesin the region 12-4 and onechalcone isomeraseand oneUDP-glycosyltransferasein the region 7-3. Transcriptomic analyses demonstrated a different expression of the detected genes in the ILs and in the DHOs compared to M82. These analyses, combined with biochemical analyses, suggested a central role of the 4-coumarate:CoA ligase in redirecting the phenylpropanoid pathways toward the biosynthesis of phenolic acids in the pyramided lines. Moreover, analyses here carried out suggest the presence in the introgression regions of novel regulatory proteins, such as one Myb4 detected on chromosome 7 and one bHLH detected in chromosome 12. Overall our data indicate that structural and regulatory genes identified in this study might have a key role for the manipulation of the phenylpropanoid metabolic pathway in tomato fruit.
authors.affiliation: Department of Agricultural Sciences, University of Naples Federico II Naples, Italy.
authors.forename: Maria Manuela
authors.initials: MM
authors.lastname: Rigano
authors.affiliation: Department of Agricultural Sciences, University of Naples Federico II Naples, Italy.
authors.forename: Assunta
authors.initials: A
authors.lastname: Raiola
authors.affiliation: Istituto di Bioscienze e BioRisorse, UOS Portici, Consiglio Nazionale delle Ricerche Naples, Italy.
authors.forename: Teresa
authors.initials: T
authors.lastname: Docimo
authors.affiliation: Department of Agricultural Sciences, University of Naples Federico II Naples, Italy.
authors.forename: Valentino
authors.initials: V
authors.lastname: Ruggieri
authors.affiliation: Department of Agricultural Sciences, University of Naples Federico II Naples, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Calafiore
authors.affiliation: Department of Agricultural Sciences, University of Naples Federico II Naples, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Vitaglione
authors.affiliation: Department of Agricultural Sciences, University of Naples Federico II Naples, Italy.
authors.forename: Rosalia
authors.initials: R
authors.lastname: Ferracane
authors.affiliation: Department of Agricultural Sciences, University of Naples Federico II Naples, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Frusciante
authors.affiliation: Department of Agricultural Sciences, University of Naples Federico II Naples, Italy.
authors.forename: Amalia
authors.initials: A
authors.lastname: Barone
keywords: chlorogenic acid; flavonoids; introgression lines; phenolic acids; pyramided lines