title: Tomato fruit photosynthesis is seemingly unimportant in primary metabolism and ripening but plays a considerable role in seed development.
abstract: Fruit of tomato (Solanum lycopersicum), like those from many species, have been characterized to undergo a shift from partially photosynthetic to truly heterotrophic metabolism. While there is plentiful evidence for functional photosynthesis in young tomato fruit, the rates of carbon assimilation rarely exceed those of carbon dioxide release, raising the question of its role in this tissue. Here, we describe the generation and characterization of lines exhibiting a fruit-specific reduction in the expression of glutamate 1-semialdehyde aminotransferase (GSA). Despite the fact that these plants contained less GSA protein and lowered chlorophyll levels and photosynthetic activity, they were characterized by few other differences. Indeed, they displayed almost no differences in fruit size, weight, or ripening capacity and furthermore displayed few alterations in other primary or intermediary metabolites. Although GSA antisense lines were characterized by significant alterations in the expression of genes associated with photosynthesis, as well as with cell wall and amino acid metabolism, these changes were not manifested at the phenotypic level. One striking feature of the antisense plants was their seed phenotype: the transformants displayed a reduced seed set and altered morphology and metabolism at early stages of fruit development, although these differences did not affect the final seed number or fecundity. Taken together, these results suggest that fruit photosynthesis is, at least under ambient conditions, not necessary for fruit energy metabolism or development but is essential for properly timed seed development and therefore may confer an advantage under conditions of stress.
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Lytovchenko
authors.forename: Ira
authors.initials: I
authors.lastname: Eickmeier
authors.forename: Clara
authors.initials: C
authors.lastname: Pons
authors.forename: Sonia
authors.initials: S
authors.lastname: Osorio
authors.forename: Marek
authors.initials: M
authors.lastname: Szecowka
authors.forename: Kerstin
authors.initials: K
authors.lastname: Lehmberg
authors.forename: Stephanie
authors.initials: S
authors.lastname: Arrivault
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tohge
authors.forename: Benito
authors.initials: B
authors.lastname: Pineda
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Anton
authors.forename: Boris
authors.initials: B
authors.lastname: Hedtke
authors.forename: Yinghong
authors.initials: Y
authors.lastname: Lu
authors.forename: Joachim
authors.initials: J
authors.lastname: Fisahn
authors.forename: Ralph
authors.initials: R
authors.lastname: Bock
authors.forename: Mark
authors.initials: M
authors.lastname: Stitt
authors.forename: Bernhard
authors.initials: B
authors.lastname: Grimm
authors.forename: Antonio
authors.initials: A
authors.lastname: Granell
authors.forename: Alisdair R
authors.initials: AR
authors.lastname: Fernie
mesh_terms: D000622:Aminolevulinic Acid / Q000378:metabolism; D005638:Fruit / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D005966:Glucuronidase; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity; D010641:Phenotype; D010788:Photosynthesis / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D012098:Reproduction; D012639:Seeds / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D000622:Aminolevulinic Acid; D005966:Glucuronidase