La acción del fruto en el control del desarrollo del níspero japonés (Eriobotrya Japonica Lindl.)

Este estudio aborda la acción del fruto como órgano de control del desarrollo del árbol frutal en el níspero japonés (Eriobotrya japonica (Thunb) Lindl.). Para ello se establecieron 4 niveles de comparación: dos cultivares, "Algerie" y "Piera", el primero con un comportamiento típico en Clima Mediterráneo, el segundo de brotación, floración, fructificación y maduración recurrentes a lo largo del año; árboles jóvenes (3 años de edad), cultivados en maceta, capaces de florecer y fructificar adecuadamente; árboles adultos en cultivo con frutos y sin ellos, eliminados en sus primeras fases de desarrollo; brotes con panícula, brotes sin ella y brotes con ésta aislada temporalmente mediante un anillado en su base. Se evaluó la brotación y la floración, el desarrollo radicular, el desarrollo del fruto, y el contenido nutricional, carbohidratos de transporte, consumo y de reserva, fracciones nitrogenadas, N-NO3; N-NH4* y N-proteico, y el contenido hormonal, AIA, ABA y zeatina, en los diferentes órganos de la planta. Los resultados indican que el árbol no inicia la brotación hasta que el fruto es recolectado y que su ausencia acelera el desborre de las yemas y el posterior desarrollo de los brotes y promueve la floración. Del mismo modo, la presencia del fruto restringe severamente el crecimiento radicular y, con ello, el aporte de hormonas a la parte aérea de la planta. Se demuestra, asimismo, que el fruto controla su propio desarrollo a través de un fenómeno de competencia nutricional con el resto de frutos de la panícula y que, a través de su interacción con el desarrollo del resto de órganos de crecimiento activo del árbol, controla el proceso de su maduración. El resultado final es que 1) la actividad fotosintética está modulada por la demanda del principal sumidero de la planta, el fruto, y que ésta, en gran medida, está regulada por la semilla que cuando completa su crecimiento cesa la demanda de carbohidratos por parte de éste; 2) la floración está controlada por el fruto, que restringe significativamente la brotación anticipada de las yemas axilares e inhibe la formación de flores en éstas panículas y en las principales; 3) el crecimiento y la actividad de las raíces se ralentizan marcadamente cuando el fruto alcanza su máximo tamaño, lo que queda demostrado por la reducción de su longitud, el descenso en la densidad de puntos mitóticos de sus tricloblastos, la reducción del transporte de azúcares desde las hojas, medido a través de la exposición de éstas a una atmósfera de 13C, la reducción del transporte desde las raíces al fruto, determinado por la acumulación de almidón y la fracción N-NH4 + , y la drástica reducción de la síntesis y transporte hormonal desde la raíz a la copa y los frutos, y 4) la acumulación de carbohidratos, junto con la reducción de la concentración de N-NH4 + y de zeatina, facilitan la maduración del fruto que es, de este modo, controlada por su propia actividad.Reig Valor, C. (2010). La acción del fruto en el control del desarrollo del níspero japonés (Eriobotrya Japonica Lindl.) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/9040Palanci

Metabolismo dei lipidi e composizione zuccherina in frutti di Avocado in pre e postraccolta

[EN] In a study of the maturity of avocado fruit it is important to elucidate the lipid metabolism in the fruit during growth and storage, since the avocado stores a large amount of lipids in the edible pulp. Meanwhile the fatty acids may then form fats by combining with glycerol, a sugar metabolism product, and sugar metabolism of the avocado fruit should be considered.[IT] Nello studio della maturazione dell¿avocado il metabolismo dei lipidi in pre e postraccolta assume un ruolo fondamentale poiché la parte edibile del frutto è caratterizzata quasi esclusivamente dall¿accumulo di grassi. Occorre comprendere anche le variazioni nella composizione zuccherina poiché la formazione degli acidi grassi è legata al glicerolo, un prodotto del metabolismo degli zuccheri.Farina, V.; Reig Valor, C. (2018). Fatty acids and sugar composition of avocado fruit during harvesting time and post-harvest ripening period: a review. Italus Hortus. 25(1):1-11. https://doi.org/10.26353/j.itahort/2018.1.111S11125

The flower to fruit transition in Citrus is partially sustained by autonomous carbohydrate synthesis in the ovary

[EN] Why evergreen fruit tree species accumulate starch in the ovary during flower bud differentiation in spring, as deciduous species do during flower bud dormancy, is not fully understood. This is because in evergreen species carbon supply is assured by leaves during flower development. We suggest the existence of an autonomous mechanism in the flowers which counteracts the competition for photoassimilates with new leaves, until they become source organs. Our hypothesis is that starch accumulated during Citrus ovary ontogeny originates from 1) its own photosynthetic capacity and 2) the mobilization of reserves. Through defoliation experiments, we found that ovaries accumulate starch during flower ontogeny using a dual mechanism: 1) the autotrophic route of source organs activating Rubisco (RbcS) genes expression, and 2) the heterotrophic route of sink organs that hydrolyze sucrose in the cytosol. Defoliation 40 days before anthesis did not significantly reduce ovary growth, flower abscission or starch concentration up to 20 days after anthesis (i.e. 60 days later). Control flowers activated the energy depletion signaling system (i.e. SnRK1) and RbcS gene expression around athesis. Defoliation accelerated and boosted both activities, increasing SPS gene expression (sucrose synthesis), and SUS1, SUS3 and cwINV (sucrose hydrolysis) to maintain a glucose threshold which satisfied its need to avoid abscission.Mesejo Conejos, C.; Martinez Fuentes, A.; Reig Valor, C.; Agustí Fonfría, M. (2019). The flower to fruit transition in Citrus is partially sustained by autonomous carbohydrate synthesis in the ovary. Plant Science. 285:224-229. https://doi.org/10.1016/j.plantsci.2019.05.014S22422928

Warm temperature during floral bud transition turns off EjTFL1 gene expression and promotes flowering in Loquat (Eriobotrya japonica Lindl)

[EN] The Rosaceae family includes several deciduous woody species whose flower development extends over two consecutive growing seasons with a winter dormant period in between. Loquat (Eriobotrya japonica Lindl.) belongs to this family, but it is an evergreen species whose flower bud initiation and flowering occur within the same growing year. Vegetative growth dominates from spring to late summer when terminal buds bloom as panicles. Thus, its floral buds do not undergo winter dormancy until flowering, but a summer heat period of dormancy is required for floral bud differentiation, and that is why we used loquat to study the mechanism by which this summer rest period contributes to floral differentiation of Rosaceae species. As for the deciduous species, the bud transition to the generative stage is initiated by the floral integrator genes. There is evidence that combinations of environmental signals and internal cues (plant hormones) control the expression of TFL1, but the mechanism by which this gene regulates its expression in loquat needs to be clarified for a better understanding of its floral initiation and seasonal growth cycles. Under high temperatures (>25 & DEG;C) after floral bud inductive period, EjTFL1 expression decreases during meristem transition to the reproductive stage, and the promoters of flowering (EjAP1 and EjLFY) increase, indicating that the floral bud differentiation is affected by high temperatures. Monitoring the apical meristem of loquat in June-August of two consecutive years under ambient and thermal controlled conditions showed that under lower temperatures (<25 & DEG;C) during the same period, shoot apex did not stop growing and a higher EjTFL1 expression was recorded, preventing the bud to flower. Likewise, temperature directly affects ABA content in the meristem paralleling EjTFL1 expression, suggesting signaling cascades could converge to refine the expression of EjTFL1 under specific conditions (T<25 & DEG;C) during the floral transition stage.García-Lorca, A.; Reig Valor, C.; Martinez Fuentes, A.; Agustí Fonfría, M.; Mesejo Conejos, C. (2023). Warm temperature during floral bud transition turns off EjTFL1 gene expression and promotes flowering in Loquat (Eriobotrya japonica Lindl). Plant Science. 335. https://doi.org/10.1016/j.plantsci.2023.11181033

Loquat Fruit Lacks a Ripening-Associated Autocatalytic Rise in Ethylene Production

[EN] Loquat is considered as a non-climacteric fruit; however, there is an evidence of a climacteric-like maturation. Therefore, it seems its ripening behavior has yet to be satisfactory classified. Because autocatalytic regulation of ethylene production during fruit ripening is one of the primary features defining climacteric-like fruit maturation, we examined its ability of autocatalysis during ripening by applying the ethylene-releasing compound ethephon to the on-tree-fruit or ethylene to detached fruit of 'Algerie' loquat and measuring its ethylene and CO2 production. We also analyzed indoleacetic acid (IAA), gibberellin, cytokinin, and abscisic acid (ABA) contents as plant hormones involved in fruit ripening. The fruit response to ethephon (500 mg l(-1)) applied at color change was immediate producing increasing amounts of ethylene during the 4 h following the treatment, but 24 h after treatment onward values were similar to those produced by untreated fruit. Similar results were obtained when applying ethylene to detached fruit (10 mu l l(-1)). Accordingly, applying ethephon (200 mg l(-1)) did not advance harvest; neither the color nor the percentage of fruit harvested at the first picking date differed significantly from the untreated fruit. Flesh firmness, total soluble solid concentration, and acidity of juice were not significantly altered either. IAA concentration reached the maximum value when fruit stopped growing, declining sharply at fruit color change; active gibberellins and cytokinins declined continuously during the fruit growth period, and ABA content sharply increased during ripening, peaking after fruit color break. Results indicate that 'Algerie' loquat lacks a ripening-associated autocatalytic rise in ethylene production, and suggest that a decline in gibberellin, cytokinin, and IAA concentrations might be needed to allow its ripening process to proceed.Reig Valor, C.; Martínez Fuentes, A.; Mesejo Conejos, C.; Rodrigo, M.; Zacarias Garcia, L.; Agustí Fonfría, M. (2016). Loquat Fruit Lacks a Ripening-Associated Autocatalytic Rise in Ethylene Production. Journal of Plant Growth Regulation. 35(1):232-244. doi:10.1007/s00344-015-9528-3S232244351Agustí M, Guardiola JL, Almela V (1981) The regulation of fruit cropping in mandarins through the use of growth regulators. Proc Int Soc Citric 1:216–220Amorós A, Zapata P, Pretel MT, Botella MA, Serrano M (2003) Physicochemical and physiological changes during fruit development and ripening of five loquat (Eriobotrya japonica Lindl.) cultivars. Food Sci Technol Int 9:43–51Ben-Arie R, Bazak H, Blumenfeld A (1986) Gibberellin delays harvest and prolongs life of persimmon fruits. Acta Hortic 179:807–813Ben-Arie R, Roisman Y, Zuthi Y, Blumenfeld A (1989) Gibberelllic acid reduces sensitivity of persimmon fruits to ethylene. In: Clijsters H, De Proft M, Marcelle R, Van Poucke M (eds) Biochemical and physiological aspects of ethylene production in lower and higher plants advances in agricultural technologies, vol 26. Springer, Netherlands, pp 165–171Blumenfeld A (1980) Fruit growth of loquat. J Am Soc Hortic Sci 105:747–750Brady CJ (1987) Fruit ripening. Ann Rev Plant Physiol 38:155–178Cai C, Xu CJ, Li X, Ferguson I, Chen KS (2006) Accumulation of lignin in relation to change in activities of lignification enzymes in loquat fruit flesh after harvest. 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Tree water status influences fruit splitting in Citrus

[EN] Fruit splitting or cracking is a major physiological disorder in fruit trees markedly influenced by environmental conditions, but conclusive data still are required to provide a definite explanation and preventive measures. Changes in climatic conditions critically influence fruit splitting incidence. We studied plant-soil-ambient water relations in splitting-prone citrus grown under 4 contrasting environmental conditions (climate type and soil), in Spain and Uruguay, over a six years period. Automatic trunk and fruit diameter measurements (trunk and fruit growth rate and maximum daily trunk shrinkage), which are a tree water status indicator, together with factors modifying the tree and fruit water relationship (temperature, ET, rainfall, soil texture, soil moisture, rootstock and xylem anatomy) were studied and correlated with splitting. A close fruit splitting and soil texture relationship was found, inversely correlated with clay and silt percentages, and positively with those for sand. Under 85%-sand soil conditions, slight changes in soil moisture due to fluctuations in temperature, ET, or rainfall changed trunk and fruit growth rate patterns during few hours and induced splitting. Splitting incidence was higher in trees with larger xylem vessels in the fruit peduncle due to rootstock ('Carrizo' and 'C-35' citrange being higher than 'FA-5', 'Cleopatra' and Poncirus trifoliata). Finally, reducing the frequency of irrigation by half increased midday canopy temperatures (similar to 5 degrees C) and splitting (+15%). We conclude that irregularities in the tree water status, due to interactions among soil moisture, rootstock and climatic conditions, leads to a number of substantial changes in fruit growth rate increasing the incidence of fruit splitting. (C) 2016 Elsevier B.V. All rights reserved.Mesejo Conejos, C.; Reig Valor, C.; Martinez Fuentes, A.; Gambetta, G.; Gravina Telechea, A.; Agustí Fonfría, M. (2016). Tree water status influences fruit splitting in Citrus. Scientia Horticulturae. 209:96-104. doi:10.1016/j.scienta.2016.06.009S9610420

Ethylene biosynthesis and perception during ripening of loquat fruit (Eriobotrya japonica Lindl.)

[EN] In order to gain insights into the controversial ripening behavior of loquat fruits, in the present study we have analyzed the expression of three genes related to ethylene biosynthesis (ACS1, ACO1 and ACO2), two ethylene receptors (ERS1a and ERS1b), one signal transduction component (CTR1) and one transcription factor (EIL1) in peel and pulp of loquat fruit during natural ripening and also in fruits treated with ethylene (10 mu LL-1) and 1-MCP (10 mu LL-1), an ethylene action inhibitor. In fruits attached to or detached from the tree, a slight increase in ethylene production was detected at the yellow stage, but the respiration rate declined progressively during ripening. Accumulation of transcripts of ethylene biosynthetic genes did not correlate with changes in ethylene production, since the maximum accumulation of ACS1 and ACO1 mRNA was detected in fully coloured fruits. Expression of ethylene receptor and signaling genes followed a different pattern in peel and pulp tissues. After fruit detachment and incubation at 20 degrees C for up to 6 days, ACS1 mRNA slightly increased, ACO1 experienced a substantial increment and ACO2 declined. In the peel, these changes were advanced by exogenous ethylene and partially inhibited by 1-MCP. In the pulp, 1-MCP repressed most of the changes in the expression of biosynthetic genes, while ethylene had almost no effects. Expression of ethylene perception and signaling genes was barely affected by ethylene or 1-MCP. Collectively, a differential transcriptional regulation of ethylene biosynthetic genes operates in peel and pulp, and support the notion of non-climacteric ripening in loquat fruits. Ethylene action, however, appears to be required to sustain or maintain the expression of specific genes. (C) 2016 Published by Elsevier GmbH.Enriqueta Alos was recipient of a post-doctoral contract JAE-DocCSIC (Fondo Social Europeo). The financial support of the researchgrants FP7-PEOPLE-2011-CIG-2011-303652 (Marie Curie Actions, European Union), AGL-2009-11558 and AGL-2012-34573 (Ministerio Economia y Competitividad, Spain), GV/2012/036 (Generalitat Valenciana, Spain) and PROMETEOII 2014/27 (Generalitat Valenciana) is gratefully acknowledged.Alós, E.; Martinez Fuentes, A.; Reig Valor, C.; Mesejo Conejos, C.; Rodrigo, M.; Agustí Fonfría, M.; Zacarias, L. (2017). Ethylene biosynthesis and perception during ripening of loquat fruit (Eriobotrya japonica Lindl.). Journal of Plant Physiology. 210:64-71. https://doi.org/10.1016/j.jplph.2016.12.008S647121

Involvement of ethylene in color changes and carotenoid biosynthesis in loquat fruit (Eriobotrya japonica Lindl. cv. Algerie)

[EN] In loquat (Eriobotrya japonica Lindl cv. Algerie) fruit, despite the non-climacteric ripening behaviour, evidence suggest that ethylene may participate in the regulation of several ripening- and postharvest-related processes. Color changes and carotenoid profile were analyzed in fruit at three developmental stages (breaker, yellow and colored fruits). At early stages, the fruit peel contained phytoene, phytofluene and other typical chloroplastic carotenoids that decreased during ripening, to accumulate ß-carotene, violaxanthin and ß-cryptoxanthin in mature fruits. In the pulp, carotenoid concentration increased during ripening to become predominant phytoene, followed by ß-carotene and ß-cryptoxanthin. Expression of the carotenoid biosynthetic genes (PSY, PDS, ZDS, CYCB and BCH) was downregulated in the peel during maturation, but increased in the pulp with the exception of BCH. The involvement of ethylene in the regulation of pigmentation was further evaluated by treating fruits at the three ripening stages with ethylene or its action inhibitor 1-MCP. At breaker fruit, ethylene accelerated and 1-MCP delayed fruit coloration, but the effect was progressively lost as fruit matured. Ethylene and 1-MCP produced different changes in carotenoids content and gene expression in peel and pulp. Application of ethylene enhanced ß-carotene content in both tissues whereas ß-cryptoxanthin was only stimulated in the pulp. 1-MCP suppressed these changes in carotenoid composition in the pulp but had little effect in the peel. A differential transcriptional level the pulp was more responsive to downregulated gene expression than the peel. Collectively, results indicate that: 1) ethylene is involved in the regulation of pigmentation and carotenoid biosynthesis in loquat fruits, 2) a differential regulation of carotenoid biosynthesis and response to ethylene appear to operate in the peel and the pulp, and 3) ß-carotene hydroxylase (BCH) is a key step in the regulation of carotenoid content and composition in both tissues of loquat fruit.Dr. E. Alos was recipient a post-doctoral contract JAE-Doc-CSIC (Fondo Social Europeo). The financial support of the research grants FP7-PEOPLE-2011-CIG-2011-303652 (Marie Curie Actions, European Union), AGL-2015-70218 (Ministerio Economia y Competitividad, Spain), GV/2012/036 (GeneralitatValenciana, Spain) and PROMETEO-II 2014/27 (Generalitat Valenciana) are gratefully acknowledged. MJR and LZ are members of Eurocaroten (COST_Action CA15136) and CaRed (Spanish Carotenoid Network, BIO2015-71703-REDT and BIO2017-90877-REDT).Alós, E.; Martinez Fuentes, A.; Reig Valor, C.; Mesejo Conejos, C.; Zacarias, L.; Agustí Fonfría, M.; Rodrigo-Esteve, MJ. (2019). Involvement of ethylene in color changes and carotenoid biosynthesis in loquat fruit (Eriobotrya japonica Lindl. cv. Algerie). Postharvest Biology and Technology. 149:129-138. https://doi.org/10.1016/j.postharvbio.2018.11.022S12913814

How to interpret the students' multiple-choice test results

[ES] El Espacio Europeo de Educación Superior (EEES) es un área de la organización educativa iniciada con la Declaración de Bolonia, fomentando la evaluación del proceso de aprendizaje de los estudiantes. Esta evaluación ha de ser continua, formativa, variada, justa, conocida y exitosa. La prueba final, tanto oral como escrita, ha sido utilizada generalmente no sólo en la metodología tradicional de la enseñanza universitaria, sino también en el EEES. La prueba final se considera un buen complemento a la evaluación continua que permite evaluar el conocimiento de la asignatura. La prueba objetiva es una de las pruebas utilizadas para evaluar a los estudiantes. A pesar de que la corrección es completamente objetiva, la formulación de las preguntas y la nota mínima necesaria para superar la prueba son decisiones subjetivas de los profesores. Fruticultura es una asignatura optativa, de 6 ECTS, ubicada en el cuarto año de Ingeniería agrónoma de la Escuela Técnica Superior de Ingenieros Agrónomos de la Universitat Politècnica de València. En este trabajo se analizan las pruebas objetivas realizadas en dicha asignatura. Concretamente, se analizan un total de 40 preguntas de opción múltiple a partir de las respuestas de 50 alumnos correspondientes al curso académico 2011/2012. Todas las preguntas de opción múltiple tienen cuatro opciones de respuesta siendo sólo una la correcta. Todas las preguntas tienen la misma ponderación, y la puntuación bruta se calcula para cada sección en función del número de preguntas que el estudiante contesta correctamente (1) o incorrectamente (0). Este trabajo realiza un análisis descriptivo de cada una de las preguntas de opción múltiple, así como los coeficientes de dificultad, la discriminación y la fiabilidad, para evaluar la calidad de las preguntas formuladas en las preguntas objetivas. Los diferentes resultados se obtuvieron en función de la sección. Las secciones teóricas obtienen un mayor porcentaje de respuestas correctas que las secciones prácticas / aplicativas. Los coeficientes de prueba estimados estuvieron dentro del rango de los coeficientes aceptables para evaluar el rendimiento académico. El objetivo de este estudio es evaluar la calidad de las preguntas objetivas tipo test utilizados como parte de la evaluación con el fin de mejorar su calidad, si es necesario, y para obtener información acerca de los aciertos y errores de los alumnos.Peiró Barber, RM.; Guijarro, E.; Verdeguer Sancho, MM.; Reig Valor, C. (2013). How to interpret the students' multiple-choice test results. En New changes in technology and innovation : INNODOCT'13 : International Conference on Innovation, Documentation and Teaching Technologies, held on-line in Valencia, Spain, on 6-7 May, 2013. https://riunet.upv.es/handle/10251/30843. Universidad Politécnica de Valencia. 183-188. http://hdl.handle.net/10251/82182S18318

¿Son las encuestas de evaluación del profesorado válidas para las nuevas metodologías de enseñanza?

[ES] La creación del Espacio Europeo de Educación Superior (EEES) ha traído consigo muchos cambios en el proceso de enseñanza-aprendizaje. Se ha pasado de un sistema basado en el profesor, en “enseñar” a un proceso centrado en el estudiante, en “aprender”. Esta nueva orientación del sistema educativo ha supuesto modificaciones en la evaluación de los alumnos. El proceso de evaluación es continuo, se trata de valorar el trabajo y el progreso continuado del estudiante, más que de someterle a una única prueba en la que deba demostrar sus conocimientos. Se evalúan las competencias adquiridas. Del mismo modo en que se han modificado los métodos de evaluación del alumnado, se han adaptado los procesos de evaluación del profesorado al nuevo EEES, ya que uno de sus principales objetivos es garantizar la calidad de la enseñanza. Sin embargo, las encuestas de opinión del alumnado siguen siendo un elemento clave para la evaluación de la labor docente del profesorado universitario. En el presente artículo se plantea una reflexión sobre la objetividad y validez de dichas encuestas para evaluar a los profesores que han adoptado las nuevas metodologías de enseñanza aprendizaje, tomando como modelo la encuesta de opinión de alumnado de la Universitat Politècnica de València.Verdeguer Sancho, MM.; Reig Valor, C.; Peiró Barber, RM.; Guijarro, E. (2013). ¿Son las encuestas de evaluación del profesorado válidas para las nuevas metodologías de enseñanza?. En New changes in technology and innovation : INNODOCT'13 : International Conference on Innovation, Documentation and Teaching Technologies, held on-line in Valencia, Spain, on 6-7 May, 2013. https://riunet.upv.es/handle/10251/30843. Universidad Politécnica de Valencia. 174-182. http://hdl.handle.net/10251/82181S17418