MartÃnez Fuentes, Amparo
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MartÃnez Fuentes
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- PublicationHormonal and carbohydrate control of fruit set in avocado 'Lamb Hass'. A question of the type of inflorescence?(Elsevier, 2021-05-10) D'Asaro, Antonio; Reig Valor, Carmina; MartÃnez Fuentes, Amparo; Mesejo Conejos, Carlos; Farina, Vittorio; Agustà FonfrÃa, Manuel; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de IngenierÃa Agronómica y del Medio Natural; Università degli Studi di Palermo[EN] The avocado tree (Persea americana Mill.) has two types of shoots, indeterminate, which maintain vegetative development from an apical bud, and determinate, which do not have vegetative growth. Indeterminate shoots set fewer fruits than determinate ones, and significantly hasten physiological fruitlet abscission. The competition between vegetative and flower development is accepted as the most reasonable hypothesis to explain the differences. However, our results show that from anthesis until fruit set flowers of indeterminate inflorescences, both those remaining on the tree and those abscised, had a higher sucrose and C6 carbohydrate content than flowers of determinate ones and no differences between them were found for C7 carbohydrates, which disagrees with this hypothesis, and indicates that factors other than carbohydrate content are responsible for fruit set in avocado. At anthesis and fruit set stage, gibberellin and cytokinin concentrations (mainly GA1 and tZ, respectively) were significantly higher in flowers of determinate inflorescences than in those of indeterminate ones, indicating their higher ability to set. We conclude that fruit set is hormonally regulated in avocado, irrespective of vegetative growth. The lower fruit set of the indeterminate inflorescences does not depend on the competition for photosynthates due to the apical vegetative growth, since C6 and C7 carbohydrate availability is enough to ensure fruit set, but on their lower content of GA1 and tZ.
- PublicationSoil Temperature Regulates Fruit Color Change in Algerie Loquat: Nutritional and Hormonal Control(Springer-Verlag, 2016) Reig Valor, Carmina; Grillone, Nicola; Mesejo Conejos, Carlos; MartÃnez Fuentes, Amparo; Agustà FonfrÃa, Manuel; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de IngenierÃa Agronómica y del Medio Natural[EN] In Rosaceae fruit tree species, fruit and roots grow opposite because of carbohydrate competition, and root activity is thus reduced by fruit growth. In agreement with this, for some of these species soil temperature has been suggested as a factor regulating fruit ripening, but the mechanism with which it works remains unknown. In this study, we reduced loquat root activity by lowering soil temperature, expecting faster fruit growth and advanced fruit ripening. Eight 4-year-old 'Algerie' loquat trees, budded onto seedling rootstock, and grown outdoors in 39-l plastic containers filled with sandy-loamy soil were used. The roots of four trees were cooled by placing the containers in a cooling compartment (9.5 A degrees C), whereas those of the other four trees were maintained at air temperature (16.5 A degrees C). We measured lateral root primordia emergence, fruit diameter and fruit color development, carbohydrates and nitrogen partitioning, as well as GA, CK, IAA, ABA, and JA content. Lowering soil temperature increased carbohydrate translocation to the fruit and reduced root N uptake and translocation to both the canopy and the fruit. Changes in plant hormones were also caused by reduced soil temperature, and fruit color advanced. Loquat fruit ripened 8-10 days earlier when soil temperature was reduced to 9.5 A degrees C.
- PublicationFruit Load and Root Development in Field-Grown Loquat Trees (Eriobotrya japonica Lindl)(Springer Verlag (Germany), 2013-06) Reig Valor, Carmina; Mesejo Conejos, Carlos; MartÃnez Fuentes, Amparo; Iglesias, D.J.; Agustà FonfrÃa, Manuel; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de IngenierÃa Agronómica y del Medio Natural; Ministerio de Ciencia e InnovaciónPhotosynthate translocation to the root in loquat trees decreases as fruit develops. Thus, during the most active period of fruit development, that is, from 50 % of its final size to the beginning of fruit color change, which correspond to BBCH growth scale stages 705 and 801, both translocating and reducing carbohydrate concentrations diminish greatly. Concomitantly, the results from our experiment show an increased abscisic acid (ABA) concentration and a decrease in the respiration rate detected by an accumulation of glucose-6-phosphate, which paralleled a reduced indole-3-acetic acid (IAA) concentration in roots. As a consequence, root development was strongly and significantly reduced. Because loquat fruit develops in winter and nonshoot growth takes place at this time, our results show that root development in loquat trees is controlled by the fruit, mediated by competition for carbohydrates and modulated by hormones. The experiment was conducted using field-grown loquat during two consecutive years and by comparing fruiting and defruited trees. Fruits were detached from the trees in the early fruit developmental stage (10 % of final size, 701 BBCH growth scale), and carbohydrate concentrations in leaves, shoot bark, and roots, as well as nitrogen fractions (N-NO 3 -, N-NH 4 +, and N-proteinaceous) and hormone (IAA, zeatin, and ABA) concentrations in roots, were analyzed throughout the period of fruit development. Root development was evaluated by counting the emerging lateral root primordia during the fruit developmental stages BBCH growth scale 701-809 (fruit color fully developed). © 2012 Springer Science+Business Media, LLC.
- PublicationSynthetic Auxin 3,5,6-TPA Provokes Citrus clementina (Hort. ex Tan) Fruitlet Abscission by Reducing Photosynthate Availability(Springer Verlag, 2012) Mesejo Conejos, Carlos; Rosito, Salvatore; Reig Valor, Carmina; MartÃnez Fuentes, Amparo; Agustà FonfrÃa, Manuel; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de IngenierÃa Agronómica y del Medio NaturalThe aim of this study was to determine the effects of the synthetic auxin 3,5,6-trichloro-2-pirydiloxyacetic acid (3,5,6-TPA) on photosynthetic activity, photosynthate transport to the fruit, and fruitlet abscission to further explain the physiological basis of auxin-mediated citrus fruit thinning. Applying 15 mg l(-1) 3,5,6-TPA to trees during the fruit cell division stage significantly increased fruitlet abscission of Clementine mandarin. On treated trees, abnormal foliar development and photosynthetic damage were observed at the same time as 3,5,6-TPA reduced fruitlet growth rate. Briefly, treatment reduced chlorophyll and carotenoid concentrations and modified chlorophyll a fluorescence parameters, that is, reduced the quantum yield (Dcurrency signPSII) of the noncyclic electron transport rate, diminished the capacity to reduce the quinone pool (photochemical quenching; q(p)), and increased nonphotochemical quenching (q (N)), thereby preventing the dissipation of excess excitation energy. In addition, the net photosynthetic flux (mu mol CO2 m(-2) s(-1)) and leaf photosynthate content decreased in treated trees. As a result, the 3,5,6-TPA treatment significantly reduced the photosynthate accumulation in fruit from day 3 to day 8 after treatment, thus reducing fruitlet growth rate. Hence, treated fruitlets significantly increased ethylene production and abscised. Twenty days after treatment, chlorophyll a fluorescence parameters and fruitlet growth rate were reestablished. Accordingly, the thinning effect of 3,5,6-TPA may be due to a temporarily induced photosynthetic disorder that leads to reduction in photosynthate production and fruitlet uptake that temporarily slows its growth, triggering ethylene production and fruitlet abscission. Afterward, the remaining treated fruit overcame this effect, increased growth rate, and reached a larger size than control fruit.
- PublicationSynthetic auxin 3,5,6-TPA increases fruit size of loquat (Eriobotrya japonica Lindl.) by reducing cell turgor pressure(Elsevier, 2016) Reig Valor, Carmina; Mesejo Conejos, Carlos; MartÃnez Fuentes, Amparo; Agustà FonfrÃa, Manuel; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de IngenierÃa Agronómica y del Medio Natural; Ministerio de Ciencia e Innovación[EN] In loquat, the synthetic auxin 3,5,6-trichloro-2 pyridyloxiacetic acid (3,5,6-TPA) applied at 15 mgl(-1) at the onset of the linear fruit growth stage or one month later during the active fruit growth period, advanced fruit ripening and harvest. The treatment significantly accelerated fruit growth and enhanced final fruit diameter by 10% compared to the control. The experiment was conducted on adult trees of 'Algerie' loquat during two consecutive years. 3,5,6-TPA (as a free acid) was sprayed by handgun to the entire tree until the point of run off, using a randomized design with one-tree plots and 8-10 replications. Cell sap water and osmotic potential were measured at the onset of colour change in treated fruit. Fruit growth rate and carbohydrate concentrations were periodically evaluated and at the first harvest date, fruit colour, fruit weight, plant hormone (ABA, GA, IAA, tZ, and JA) content, total soluble solids, titratable acidity, and number of fruits harvested were also recorded. Results confirmed that the effect of 3,5,6-TPA increasing fruit size is due to a reduction of fruit cell turgor pressure that diminished water potential, improving water uptake and increasing carbohydrate contents. (C) 2016 Elsevier B.V. All rights reserved.
- PublicationIn loquat (Eriobotrya japonica Lindl.) return bloom depends on the time the fruit remains on the tree(Springer Verlag (Germany), 2014-12) Reig Valor, Carmina; Mesejo Conejos, Carlos; MartÃnez Fuentes, Amparo; Agustà FonfrÃa, Manuel; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de IngenierÃa Agronómica y del Medio Natural; Ministerio de Ciencia e InnovaciónIn loquat (Eriobotrya japonica Lindl.), the comparison of fruiting trees and defruited trees carried out covering a range of developmental fruit stages reveals a significant reduction in flowering due to fruit from its early stage of development, being higher when it changes color and becomes senescent, which coincides with the floral bud inductive period. This effect occurred both at the tree and at the shoot level. Furthermore, although current shoots almost always develop into panicles, those from fruiting trees develop fewer flowers, suggesting that fruit also affects at the floral bud level. In our experiment, the gibberellin concentration at the floral bud inductive period was significantly higher in bark tissues (periderm, cortex and phloem tissues) of fruiting trees, compared with defruited trees that tend to flower more. The lower concentration of IAA in the bark tissues of defruited trees also contributes to increase their flowering intensity. On the contrary, the zeatin concentration was higher. Accordingly, at bud burst, the IAA/zeatin ratio, an indication of effect on flowering, was significantly higher for fruiting trees. Some disruption in the nitrate reduction process in fruiting tree was also observed. The process of floral bud induction and differentiation was not associated with either reducing or translocating and reserve carbohydrate concentration. Hence, loquat flower intensity depends on the time the fruit is maintained on the tree. The intensity is affected indirectly, by reducing the number of shoots, and directly, by reducing the number of flowers per panicle, and these effects are linked to endogenous plant hormone contents.
- PublicationHormonal and Nutritional Changes in the Flavedo Regulating Rind Color Development in Sweet Orange [Citrus sinensis (L.) Osb.](Springer Verlag, 2012) Gambetta Romaso, MarÃa Giuliana; MartÃnez Fuentes, Amparo; Bentancur, Oscar; Mesejo Conejos, Carlos; Reig Valor, Carmina; Gravina, Alfredo; Agustà FonfrÃa, Manuel; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de IngenierÃa Agronómica y del Medio Natural; European Commission; Comisión Sectorial de Investigación CientÃfica, Uruguay; Universidad de la República, UruguayThe objective of this research was to determine the changes in the levels of endogenous gibberellins GA(1) and GA(4), abscisic acid (ABA), and ethylene during fruit coloring of on-tree fruits of sweet orange. The time course of carbohydrates and nitrogen content in the flavedo prior to fruit color break and during peel ripening were also studied. To identify nutritional and hormonal changes in the fruit, 45 days before fruit color break the peduncles of 15-30 fruits per tree of 'Washington' navel, 'Navelate,' and 'Valencia Delta Seedless' sweet orange, located in single-fruited shoots, were girdled to intercept phloem transport. A set of 15-30 fruits per tree remained intact on the peduncle for control. Girdling significantly delayed fruit coloration for more than 2 months; the delay paralleled higher GA(1) and GA(4) concentrations in the flavedo and retarded the rise of ABA concentration prior to color break. Girdling also reduced carbohydrate concentrations and increased N concentrations in the flavedo compared to control fruits; no ethylene production was detected. Therefore, in sweet orange, fruit changes color by reducing active gibberellin concentrations in the flavedo, which are involved in regulating sugars and ABA accumulation and in reducing N fraction concentration as rind color develops. This was demonstrated in vivo without removing the fruit from the tree. Comparable results were obtained with experiments carried out over four consecutive years in two countries (Spain and Uruguay).
- PublicationAdvances in Citrus Flowering: A Review(Frontiers Media SA, 2022-04-08) Agustà FonfrÃa, Manuel; Reig Valor, Carmina; MartÃnez Fuentes, Amparo; Mesejo Conejos, Carlos; Dpto. de Producción Vegetal; Instituto Agroforestal Mediterráneo; Escuela Técnica Superior de IngenierÃa Agronómica y del Medio Natural[EN] Citrus are polycarpic and evergreen species that flower once in spring or several times a year depending on the genotype and the climatic conditions. Floral induction is triggered by low temperature and water-deficit stress and occurs 2-3 months before bud sprouting, whereas differentiation takes place at the same time as sprouting. The induced buds develop single flowers or determinate inflorescences, so that vegetative growth is required at the axillary buds to renew the polycarpic habit. The presence of fruits inhibits sprouting and flower induction from nearby axillary buds in the current season. In some species and cultivars, this results in low flowering intensity the following spring, thus giving rise to alternate bearing. A number of key flowering genes act in the leaf (CiFT3, CcMADS19, etc.) or in the bud (CsLFY, CsTFL1, etc.) to promote or inhibit both flowering time and reproductive meristem identity in response to these climatic factors, the fruit dominance, or the age of the plant (juvenility). The expression of some of these genes can be modified by gibberellin treatments, which reduce bud sprouting and flowering in adult trees, and constitute the main horticultural technique to control flowering in citrus. This review presents a comprehensive view of all aspects of the flowering process in citrus, converging the research published during the past half century, which focused on plant growth regulators and the nutritional source-sink relationships and guided research toward the study of gene transcription and plant transformation, and the advances made with the development of the tools of molecular biology published during the current century.