title: From root to fruit: RNA-Seq analysis shows that arbuscular mycorrhizal symbiosis may affect tomato fruit metabolism.
abstract: BACKGROUND
  Tomato (Solanum lycopersicum) establishes a beneficial symbiosis with arbuscular mycorrhizal (AM) fungi. The formation of the mycorrhizal association in the roots leads to plant-wide modulation of gene expression. To understand the systemic effect of the fungal symbiosis on the tomato fruit, we used RNA-Seq to perform global transcriptome profiling on Moneymaker tomato fruits at the turning ripening stage.
  
  
  RESULTS
  Fruits were collected at 55 days after flowering, from plants colonized with Funneliformis mosseae and from control plants, which were fertilized to avoid responses related to nutrient deficiency. Transcriptome analysis identified 712 genes that are differentially expressed in fruits from mycorrhizal and control plants. Gene Ontology (GO) enrichment analysis of these genes showed 81 overrepresented functional GO classes. Up-regulated GO classes include photosynthesis, stress response, transport, amino acid synthesis and carbohydrate metabolism functions, suggesting a general impact of fungal symbiosis on primary metabolisms and, particularly, on mineral nutrition. Down-regulated GO classes include cell wall, metabolism and ethylene response pathways. Quantitative RT-PCR validated the RNA-Seq results for 12 genes out of 14 when tested at three fruit ripening stages, mature green, breaker and turning. Quantification of fruit nutraceutical and mineral contents produced values consistent with the expression changes observed by RNA-Seq analysis.
  
  
  CONCLUSIONS
  This RNA-Seq profiling produced a novel data set that explores the intersection of mycorrhization and fruit development. We found that the fruits of mycorrhizal plants show two transcriptomic "signatures": genes characteristic of a climacteric fleshy fruit, and genes characteristic of mycorrhizal status, like phosphate and sulphate transporters. Moreover, mycorrhizal plants under low nutrient conditions produce fruits with a nutrient content similar to those from non-mycorrhizal plants under high nutrient conditions, indicating that AM fungi can help replace exogenous fertilizer for fruit crops.
authors.forename: Inès
authors.initials: I
authors.lastname: Zouari
authors.forename: Alessandra
authors.initials: A
authors.lastname: Salvioli
authors.forename: Matteo
authors.initials: M
authors.lastname: Chialva
authors.forename: Mara
authors.initials: M
authors.lastname: Novero
authors.forename: Laura
authors.initials: L
authors.lastname: Miozzi
authors.forename: Gian Carlo
authors.initials: GC
authors.lastname: Tenore
authors.forename: Paolo
authors.initials: P
authors.lastname: Bagnaresi
authors.affiliation: Department of Life Sciences and Systems Biology, University of Turin, Viale Mattioli 25, 10125 Turin, Italy. paola.bonfante@unito.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Bonfante
mesh_terms: D050260:Carbohydrate Metabolism / Q000235:genetics; D002473:Cell Wall / Q000378:metabolism; D016000:Cluster Analysis; D005638:Fruit / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D055137:Glomeromycota / Q000502:physiology; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism*; D010788:Photosynthesis / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D017423:Sequence Analysis, RNA; D013559:Symbiosis; D059467:Transcriptome
chemical_list: D010940:Plant Proteins