title: The tomato FRUITFULL homologs TDR4/FUL1 and MBP7/FUL2 regulate ethylene-independent aspects of fruit ripening.
abstract: Tomato (Solanum lycopersicum) contains two close homologs of the Arabidopsis thaliana MADS domain transcription factor FRUITFULL (FUL), FUL1 (previously called TDR4) and FUL2 (previously MBP7). Both proteins interact with the ripening regulator RIPENING INHIBITOR (RIN) and are expressed during fruit ripening. To elucidate their function in tomato, we characterized single and double FUL1 and FUL2 knockdown lines. Whereas the single lines only showed very mild alterations in fruit pigmentation, the double silenced lines exhibited an orange-ripe fruit phenotype due to highly reduced lycopene levels, suggesting that FUL1 and FUL2 have a redundant function in fruit ripening. More detailed analyses of the phenotype, transcriptome, and metabolome of the fruits silenced for both FUL1 and FUL2 suggest that the genes are involved in cell wall modification, the production of cuticle components and volatiles, and glutamic acid (Glu) accumulation. Glu is responsible for the characteristic umami taste of the present-day cultivated tomato fruit. In contrast with previously identified ripening regulators, FUL1 and FUL2 do not regulate ethylene biosynthesis but influence ripening in an ethylene-independent manner. Our data combined with those of others suggest that FUL1/2 and TOMATO AGAMOUS-LIKE1 regulate different subsets of the known RIN targets, probably in a protein complex with the latter.
authors.affiliation: Department of Plant Cell Biology, Radboud University Nijmegen, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Marian
authors.initials: M
authors.lastname: Bemer
authors.forename: Rumyana
authors.initials: R
authors.lastname: Karlova
authors.forename: Ana Rosa
authors.initials: AR
authors.lastname: Ballester
authors.forename: Yury M
authors.initials: YM
authors.lastname: Tikunov
authors.forename: Arnaud G
authors.initials: AG
authors.lastname: Bovy
authors.forename: Mieke
authors.initials: M
authors.lastname: Wolters-Arts
authors.forename: Priscilla de Barros
authors.initials: Pde B
authors.lastname: Rossetto
authors.forename: Gerco C
authors.initials: GC
authors.lastname: Angenent
authors.forename: Ruud A
authors.initials: RA
authors.lastname: de Maagd
mesh_terms: D002338:Carotenoids / Q000378:metabolism; D015536:Down-Regulation; D005030:Ethylenes / Q000378:metabolism; D005638:Fruit / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018698:Glutamic Acid / Q000378:metabolism; D018551:Solanum lycopersicum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism; D055442:Metabolome; D055432:Metabolomics; D008954:Models, Biological; D009154:Mutation; D009822:Oils, Volatile / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D059467:Transcriptome; D015854:Up-Regulation
chemical_list: D005030:Ethylenes; D026161:MADS Domain Proteins; D009822:Oils, Volatile; D010937:Plant Growth Regulators; D010940:Plant Proteins; D002338:Carotenoids; D018698:Glutamic Acid; C036216:ethylene