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RESEARCH PRODUCT
Gibberellin reactivates and maintains ovary-wall cell division causing fruit set in parthenocarpic Citrus species
Mª Antonietta GermanàAlmudena BermejoEduardo Primo-milloAmparo Martínez-fuentesManuel AgustíCarlos MesejoCarmina ReigNatalia Muñoz-fambuenaRoberto YusteDomingo J. Iglesiassubject
0106 biological sciences0301 basic medicineCitrusCell divisionFruit setCitruFlowersPlant ScienceOrange (colour)BiologyParthenocarpy01 natural sciencesPaclobutrazol03 medical and health scienceschemistry.chemical_compoundPlant Growth RegulatorsGeneticAnthesisCell WallGene Expression Regulation PlantBotanyPRODUCCION VEGETALGeneticsGibberellinPhylogenyFruit treePlant Growth Regulatorfood and beveragesSequence Analysis DNAGeneral Medicinebiology.organism_classificationGibberellinsUp-RegulationCitrus unshiu030104 developmental biologychemistryFlowerFruitMicroscopy Electron ScanningParthenocarpyGibberellinAgronomy and Crop ScienceCell DivisionFruit tree010606 plant biology & botanydescription
[EN] Citrus is a wide genus in which most of the cultivated species and cultivars are natural parthenocarpic mutants or hybrids (i.e. orange, mandarin, tangerine, grapefruit). The autonomous increase in GA(1) ovary concentration during anthesis was suggested as being the stimulus responsible for parthenocarpy in Citrus regardless of the species. To determine the exact GA-role in parthenocarpic fruit set, the following hypothesis was tested: GA triggers and maintains cell division in ovary walls causing fruit set. Obligate and facultative parthenocarpic Citrus species were used as a model system because obligate parthenocarpic Citrus sp (i.e. Citrus unshiu) have higher GA levels and better natural parthenocarpic fruit set compared to other facultative parthenocarpic Citrus (i.e. Citrus clementina). The autonomous activation of GA synthesis in C. unshiu ovary preceded cell division and CYCA1.1 up regulation (a G2-stage cell cycle regulator) at anthesis setting a high proportion of fruits, whereas C. clementina lacked this GA-biosynthesis and CYCA1.1 up-regulation failing in fruit set. In situ hybridization experiments revealed a tissue-specific expression of GA20ox2 only in the dividing tissues of the pericarp. Furthermore, CYCA1.1 expression correlated endogenous GA(1) content with GA(3) treatment, which stimulated cell division and ovary growth, mostly in C clementina. Instead, paclobutrazol (GA biosynthesis inhibitor) negated cell division and reduced fruit set. Results suggest that in parthenocarpic citrus the specific GA synthesis in the ovary walls at anthesis triggers cell division and, thus, the necessary ovary growth rate to set fruit. (C) 2016 Elsevier Ireland Ltd. All rights reserved.
year | journal | country | edition | language |
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2016-01-01 | Plant Science |