Martínez Fuentes, Amparo
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Martínez Fuentes
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Amparo
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- PublicationGibberellin reactivates and maintains ovary-wall cell division causing fruit set in parthenocarpic Citrus species(Elsevier, 2016) Mesejo Conejos, Carlos; Yuste Gallasch, Roberto; Reig Valor, Carmina; Martínez Fuentes, Amparo; Iglesias, Domingo; Muñoz Fambuena, Natalia; Bermejo del Castillo, Almudena; Germanà, Maria Antonietta; Primo Millo, Eduardo; Agustí Fonfría, Manuel; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de Ingeniería Agronómica y del Medio Natural[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.
- PublicationFruit-dependent epigenetic regulation of flowering in Citrus(Blackwell Publishing, 2020-01) Agustí Fonfría, Manuel; Mesejo Conejos, Carlos; Muñoz-Fambuena, Natalia; Vera Sirera, Francisco José; de Lucas, Miguel; Martínez Fuentes, Amparo; Reig Valor, Carmina; Iglesias, Domingo J.; Primo-Millo, Eduardo; Blazquez Rodriguez, Miguel Angel; Dpto. de Producción Vegetal; Instituto Universitario Mixto de Biología Molecular y Celular de Plantas; Dpto. de Biotecnología; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de Ingeniería Agronómica y del Medio Natural; Ministerio de Economía y Competitividad; Università degli Studi di Palermo; Ministerio de Ciencia e Innovación[EN] In many perennial plants, seasonal flowering is primarily controlled by environmental conditions, but in certain polycarpic plants, environmental signals are locally gated by the presence of developing fruits initiated in the previous season through an unknown mechanism. Polycarpy is defined as the ability of plants to undergo several rounds of reproduction during their lifetime, alternating vegetative and reproductive meristems in the same individual. To understand how fruits regulate flowering in polycarpic plants, we focused on alternate bearing in Citrus trees that had been experimentally established as fully flowering or nonflowering. We found that the presence of the fruit causes epigenetic changes correlating with the induction of the CcMADS19 floral repressor, which prevents the activation of the floral promoter CiFT2 even in the presence of the floral inductive signals. By contrast, newly emerging shoots display an opposite epigenetic scenario associated with CcMADS19 repression, thereby allowing the activation of CiFT2 the following cold season.
- PublicationFruit load restricts the flowering promotion effect of paclobutrazol in alternate bearing Citrus spp(Elsevier, 2013-02-28) Martínez Fuentes, Amparo; Mesejo Conejos, Carlos; Muñoz Fambuena, Natalia; Reig Valor, Carmina; Gonzalez Más, Mª Carmen; Iglesias, D. J.; Primo Millo, Eduardo; Agustí Fonfría, Manuel; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de Ingeniería Agronómica y del Medio Natural; Ministerio de Ciencia e InnovaciónThe floral bud inductive period, PBZ promotes flowering in Citrus; however, our results indicate that this effect is fruit-load dependant. In 'Salustiana' and 'Navelina' sweet oranges, 'Hernandina' Clementine mandarin, and 'Afourer' and 'Moncada' hybrids, flowering intensity significantly increased the following spring for medium-to-low fruit-load trees treated with either 1-10g PBZ tree(-1) applied to the soil or 15 g tree(-1) sprayed on the canopy. PBZ significantly increased the percentage of sprouted buds and leafless floral shoots (both single-flowered shoots and inflorescences) and reduced the number of vegetative shoots. By contrast, heavy fruit load trees receiving the same amount of PBZ in the same season or at floral bud differentiation period scarcely flowered. Fruit nullified the effect of PBZ irrespective to treatment date (inductive period or bud burst) as well as the dose applied (1, 10 or 15 g tree(-1)) or the treatment method (soil application or canopy spraying). In conclusion, the effectiveness of PBZ in promoting flowering in Citrus depends on the fruit load since the tree showed a cultivar-dependant threshold value above which PBZ is unable to promote flowering. (C) 2012 Elsevier B.V. All rights reserved.
- PublicationGenetic inhibition of flowering differs between juvenile and adult Citrus trees(Oxford University Press, 2019-02-15) Muñoz Fambuena, Natalia; Nicolas-Almansa, M.; Martínez Fuentes, Amparo; Reig Valor, Carmina; Iglesias, D. J.; Primo-Millo, Eduardo; Mesejo Conejos, Carlos; Agustí Fonfría, Manuel; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de Ingeniería Agronómica y del Medio Natural; Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria[EN] Background and Aims In woody species, the juvenile period maintains the axillary meristems in a vegetative stage, unable to flower, for several years. However, in adult trees, some 1-year-old meristems flower whereas others remain vegetative to ensure a polycarpic growth habit. Both types of trees, therefore, have non-flowering meristems, and we hypothesize that the molecular mechanism regulating flower inhibition in juvenile trees is different from that in adult trees. Methods In adult Citrus trees, the main endogenous factor inhibiting flower induction is the growing fruit. Thus, we studied the expression of the main flowering time, identity and patterning genes of trees with heavy fruit load (not-flowering adult trees) compared to that of 6-month-old trees (not-flowering juvenile trees). Adult trees without fruits (flowering trees) were used as a control. Second, we studied the expression of the same genes in the meristems of 6-month, and 1-, 3-, 5-and 7-year-old juvenile trees compared to 10-year-old flowering trees. Key Results The axillary meristems of juvenile trees are unable to transcribe flowering time and patterning genes during the period of induction, although they are able to transcribe the FLOWERING LOCUS T citrus orthologue (CiFT2) in leaves. By contrast, meristems of not-flowering adult trees are able to transcribe the flowering network genes but fail to achieve the transcription threshold required to flower, due to CiFT2 repression by the fruit. Juvenile meristems progressively achieve gene expression, with age-dependent differences from 6 months to 7 years, FD-like and CsLFY being the last genes to be expressed. Conclusions During the juvenile period the mechanism inhibiting flowering is determined in the immature bud, so that it progressively acquires flowering ability at the gene expression level of the flowering time programme, whereas in the adult tree it is determined in the leaf, where repression of CiFT2 gene expression occurs.
- PublicationCell division interference in newly fertilized ovules induces stenospermocarpy in cross-pollinated citrus fruit(Elsevier, 2014-08) Mesejo Conejos, Carlos; Muñoz Fambuena, Natalia; Reig Valor, Carmina; Martínez Fuentes, Amparo; Agustí Fonfría, Manuel; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de Ingeniería Agronómica y del Medio NaturalSeedlessness is a highly desirable characteristic in fresh fruits. However, post-fertilization seed abortion of cross-pollinated citrus fruit is uncommon. The factors regulating stenospermocarpy in citrus are unknown. In this research, we induced stenospermocarpy interfering in newly fertilized ovule cell division. The research also elucidates the most sensitive stage for ovule/seed abortion in citrus. Experiments were conducted with 'Afourer' mandarin that cross-pollinates with several cultivars and species. Cross-pollinated fruitlets were treated with maleic hydrazide (MH), a systemic growth regulator that specifically interferes in cell division. MH reduced ovule growth rate, the number of cell layers in nucella and inhibited embryo sac expansion; moreover, the treatment increased callose accumulation in nucella and surrounding the embryo sac. Fruits developed an early-aborted seed type with an immature, soft and edible seed coat. Seed number (-80%) and seed weight (-46%) were reduced in mature fruits. MH also hampered cell division in ovary walls, mesocarp and endocarp, thus reducing daily fruitlet growth and increasing fruit abscission. Stenospermocarpy could only be induced for a short period of time in the progamic phase of fertilization, specifically, when ovules are ready to be fertilized (7 days after anthesis) to early stages of embryo sac deyelopment (14 days after anthesis). (C) 2014 Elsevier Ireland Ltd. All rights reserved.