Papers by Francisco José García Breijo
This project was funded by the Spanish Ministry of Education and Science [CGL2006-12917-C02-01, C... more This project was funded by the Spanish Ministry of Education and Science [CGL2006-12917-C02-01, CGL2009-13429_C02-00], and the Generalitat Valenciana [PROMETEO 174/2008 GVA].
Scientia Horticulturae, 2019
Obtaining citrus fruits without seeds is a recurrent objective for farmers as it is one of the mo... more Obtaining citrus fruits without seeds is a recurrent objective for farmers as it is one of the most valued characteristics, especially in mandarins. 'Afourer' tangor is a highly valuable well-established mandarin, and a high percentage of seeded fruits are produced under cross-pollination conditions. Several agronomic techniques have been suggested to control presence of seeds, such as covering with nets and copper sulfate (CuSO 4) and gibberellic acid (GA 3) treatments. Natural bee repellents are also proposed to reduce the number of seeds per fruit. In this study, we aimed to compare the effect of several agronomic treatments to reduce the seed number in 'Afourer' mandarin. To this end, we assessed the effect of chemical and bee repellent treatments on the seed number per fruit and the side effect on yield and fruit diameter. Under these experimental conditions the two bee repellents, one based on zinc and one based on Capsicum annuum, were not useful for reducing the seed number per fruit in 'Afourer' mandarin. The copper sulfate + GA 3 treatment reduced the seed number per fruit by only 35%, and this efficiency was clearly not enough to reduce the seed number for commercial purposes. The most effective method to reduce the seed number per fruit was covering with nets, but this technique led to markedly reduced yields. Yield data was highly variable. Fruit diameter correlated positively with the seed number, but it was a weak relationship as the seed number explained only 15% of fruit size variability (R 2 = 0.15). acteristics, especially in mandarins (Roldán and Navarro, 2001; Gambetta et al., 2013). Consequently, obtaining citrus fruits without seeds has become a recurrent objective for farmers as it can improve price and sale expectations (Vardi et al., 2008). The most cultivated mandarin varieties are parthenocarpic and selfincompatible and, therefore, they produce fruits without seeds in the absence of cross-pollination (Soost, 1965). However, when mandarin varieties are grown close to compatible ones, like other mandarins or tangor hybrids, they produce several seeds per fruit (Cronje et al., 2014). The use of new hybrid varieties with a better potential price or to prolong the offer period has been extended in the last decades (Bono et al., 2000). Many of these new varieties are pollen-compatible with traditional ones and are, therefore, directly involved in the presence of seeds. 'Afourer' tangor presents organoleptic and ripening characteristics that are well appreciated by the fresh market (Nadori, 2004). This variety, also known as 'Nadorcott', originated in Afourer (Morocco) and is probably a hybrid of cv. 'Murcott' ('Murcott' is a tangor hybrid of tangerine and orange, Citrus reticulata Blanco x C. sinensis (L.) Osbeck) and an unknown pollinator parent (Nadori, 1998, 2004). 'Afourer' is reported to be self-incompatible and produces seedless fruit if grown in isolation (Bono et al., 2000; Chao, 2005). However, under cross-pollination conditions, a high percentage of seeded fruits are produced (Agustí et al., 2005; Chao, 2005). The 'Afourer' flowering period widely overlaps many other pollen-compatible varieties, such as cv. 'Nova' (the
Trees, 2015
Key message The speed of infection of Quercus ilex by Phytophthora cinnamomi is influenced by the... more Key message The speed of infection of Quercus ilex by Phytophthora cinnamomi is influenced by the method of inoculation used, and structural changes in the host do not differ depending on whether primary or secondary roots are infected. Abstract This study aimed to elucidate the infection process of the invasive pathogen Phytophthora cinnamomi on primary and secondary roots of 2-month-old Quercus ilex seedlings. To test if different methods of inoculation lead to different changes in the host caused by the pathogen, the root system of plants was either immersed into a suspension of P. cinnamomi zoospores, or placed in direct contact with agar plugs colonized by P. cinnamomi mycelium. Histology of root sections obtained every 24 h for 10 days revealed similar changes in the structure of cells and tissues of the host irrespective of the inoculation method used. However, the immersion method resulted in a delay in the colonization of the host, different aerial symptoms, and the formation of different reproductive structures of the pathogen. Emerging secondary and tertiary roots and sites where secondary or tertiary roots were about to emerge were identified as main entry points. Hyphae in the xylem tissues were more frequently found in secondary than in primary roots, but in both types of roots the phloem was the most important pathway of colonization. For the first time in the interaction between Q. ilex and P. cinnamomi, transmission electron microscopy was used to describe degradation of the host cell walls, pit penetration and extrahaustorial matrix. Haustoria development during intracellular growth and hyphal aggregations (stromata) caused no damage to the host cell walls indicating hemibiotrophic parasitism.
Biology
Two microalgal species, Trebouxia jamesii and Trebouxia sp. TR9, were detected as the main photob... more Two microalgal species, Trebouxia jamesii and Trebouxia sp. TR9, were detected as the main photobionts coexisting in the thalli of the lichen Ramalina farinacea. Trebouxia sp. TR9 emerged as a new taxon in lichen symbioses and was successfully isolated and propagated in in vitro culture and thoroughly investigated. Several years of research have confirmed the taxon Trebouxia sp. TR9 to be a model/reference organism for studying mycobiont–photobiont association patterns in lichen symbioses. Trebouxia sp. TR9 is the first symbiotic, lichen-forming microalga for which an exhaustive characterization of cellular ultrastructure, physiological traits, genetic and genomic diversity is available. The cellular ultrastructure was studied by light, electron and confocal microscopy; physiological traits were studied as responses to different abiotic stresses. The genetic diversity was previously analyzed at both the nuclear and organelle levels by using chloroplast, mitochondrial, and nuclear ge...
Journal of Plant Science and Phytopathology, 2021
The efficacy of chitosan and silicon oxide to prevent postharvest weight loss and fungi infection... more The efficacy of chitosan and silicon oxide to prevent postharvest weight loss and fungi infection in 'Valencia Late' oranges was tested. Three silicon oxide concentrations (0.1%, 0.2%, 1%) were applied as preharvest treatments. Chitosan treatments were performed at the same concentrations in postharvest fruit. Preharvest applications were carried out by tractor spraying, while fruit were submerged for 30 seconds in baths with the chitosan concentrations in the postharvest applications. In both cases, a positive control (water treatment) and negative control (fungicide) were included. Treated fruit were stored in a chamber to simulate commercial storage conditions (4 ºC, 90% RH) for 9 weeks. After this time, the weight loss and damage caused by fungi due to natural infection were evaluated. Both silicon oxide and chitosan applications were effective in controlling natural infection by Penicillium species but had no positive effect on weight loss.
PLOS ONE, 2019
Background In Citrus spp., gibberellic acid (GA) has been proposed to improve different processes... more Background In Citrus spp., gibberellic acid (GA) has been proposed to improve different processes related to crop cycle and yield. Accordingly, many studies have been published about how GA affects flowering and fruiting. Nevertheless, some such evidence is contradictory and the use of GA applications by farmers are still confusing and lack the expected results. Purpose This review aims to collate, present, analyze and synthesize the most relevant empirical evidence to answer the following questions: (i) how does gibberellic acid act on flowering and fruiting of citrus trees?; (ii) why is all this knowledge sometimes not correctly used by farmers to solve yield problems relating to flowering and fruit set? Methods An extensive literature search to obtain a large number of records about the topic was done. Searches were done in five databases: WoS, Scopus, Google Academics, PubMed and Scielo. The search string used was "Gibberellic acid" AND "Citrus". Records were classified into 11 groups according to the development process they referred to and initial data extraction was done. Records related with flowering and fruit set were drawn, and full texts were screened. Fifty-eight full text records were selected for the final data extraction. Results Selected studies were published from 1959 to 2017 and were published mainly in Spain, USA, Brazil and Japan. Twelve species were studied, and Citrus sinensis, C. reticulata and C. unshiu were the principal ones. Most publications with pre-flowering treatments agreed that GA decreases flowering, while only 3 out of 18 did not observe any effect. In most of these studies, the effect on fruit set and yield was not evaluated. Studies with treatments at full bloom or some weeks later mostly reported increased fruit set. However, these
PLos ONE, 2019
Background In Citrus spp., gibberellic acid (GA) has been proposed to improve different processes... more Background In Citrus spp., gibberellic acid (GA) has been proposed to improve different processes related to crop cycle and yield. Accordingly, many studies have been published about how GA affects flowering and fruiting. Nevertheless, some such evidence is contradictory and the use of GA applications by farmers are still confusing and lack the expected results. Purpose This review aims to collate, present, analyze and synthesize the most relevant empirical evidence to answer the following questions: (i) how does gibberellic acid act on flowering and fruiting of citrus trees?; (ii) why is all this knowledge sometimes not correctly used by farmers to solve yield problems relating to flowering and fruit set?
Three species of Eremurus M. Bieb. grown at UASVM Iasi, Romania, were studied: E. himalaicus Bake... more Three species of Eremurus M. Bieb. grown at UASVM Iasi, Romania, were studied: E. himalaicus Baker, E. robustus Regel and E. stenophyllus (BOISS. & BUHSE) Bak. Some ornamental (morphologic and phenologic) features were analyzed and also the anatomic structure of the leaf, the content of photosynthetic pigments and the enzymatic activity of the leaves. The biometrical and phenological determinations indicate a good ecological adaptability of the plants, in accordance with similar reports. The anatomical differences between the three species are not very great, but the stomata in E. stenophillus and E. himalaicus are arranged at the same level as the epidermal surface while in E. robustus they are arranged a little lower, and the assimilating parenchyma layer is more developed in E. stenophillus and E. himalaicus than in E. robustus. At E. robustus and E. himalaicus a larger content of assimilatory pigments and a more reduced enzymatic activity were observed.
Symbiosis, 2020
Editor comments Please consider the comments and recommendations for revision by the Reviewers. T... more Editor comments Please consider the comments and recommendations for revision by the Reviewers. The recommendations for changes, though in some cases substantial, are well worth making as I am sure the paper will be much improved as a consequence. If there are any recommendations you do not wish to comply with, please identify these and state
is one of the most planted white grape varieties of northern Spain. A general agreement supports ... more is one of the most planted white grape varieties of northern Spain. A general agreement supports many Vitis vinifera cultivars possibly being self-fertile, although this seems to be a variety-dependent characteristic. No previous information about the mating system of cv. Macabeo was found. This study aimed to analyze its mating system and to compare the in vivo fertilization process with and without artificial cross-pollination. Two treatments were performed: emasculation and cross-pollination. The seed number was counted, and pollen tube growth was observed by microscopy. The results showed that cv. Macabeo is self-fertile and selfing probably occurs before the flower opens. Pollen was found over the stigma of flowers before capfall and ovule fertilization was observed even in emasculated flowers, which suggests that germination and pollen tube growth happened in a very early flower development stage. Cross-pollination increased the presence of the pollen tubes growing inside flowers but was not necessary for fruit set. Ovule fertilization was very fast as 24 h (h) were enough for pollen tubes to reach the end of stylar canals.
ect of chitosan and silicon oxide treatments on postharvest Valencia Late (Citrus × sinensis) fru... more ect of chitosan and silicon oxide treatments on postharvest Valencia Late (Citrus × sinensis) fruits.
Fresh market demands high quality fruit and, therefore, citrus growers and researchers are consta... more Fresh market demands high quality fruit and, therefore, citrus growers and researchers are constantly looking for solutions to avoid seed presence. Current horticultural techniques have low effectiveness or high cost. The objective of this study is to evaluate the inhibition effect of seven products on the in vivo pollen tube growth in Nadorcott mandarin, which is a high-value seedy variety. To achieve this main objective, three inorganic fertilizers (ammonium nitrate, potassium nitrate, sulfur), and four saccharides (saccharose, methyl cellulose, callose, chitosan) were applied to Nadorcott stigmas 24 h before and after hand pollination. Pollen tubes were counted 1, 3, and 5 days after treatment in longitudinal blue violet autofluorescence-stained sections. Of the seven evaluated products, only sulfur had a strong inhibitory effect. Elemental sulfur (S 8) inhibited pollen tube growth by 94-100%. This strong effect was observed regardless of sulfur being applied 24 h before or after pollination, and on fixed flowers 1, 3 or 5 days after applications. Saccharose treatment seemed to have the opposite effect: stimulated pollen tube growth, but the difference with the positive control was small and nonsignificant. The sulfur effect could be useful for designing agronomic applications capable of preventing seed presence in Nadorcott mandarin.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Nadorcott is a well-established and appreciated mandarin by the fresh market. However, it produce... more Nadorcott is a well-established and appreciated mandarin by the fresh market. However, it produces seeds due to cross-pollination with other compatible varieties, which is quite frequent in most producing countries. Consumers prefer seedless mandarins and, therefore, citrus growers need techniques to avoid seeds forming. This study aims to evaluate the effect of six treatments (ammonium nitrate, potassium nitrate, sulfur, saccharose, methylcellulose, callose) on seed number per fruit when applied to Nadorcott trees. In this way, we evaluate which of them is more efficient and can be used in the future as an agronomic treatment to avoid seeds in mandarins. The effect of treatments on yield and fruit quality is also reported. To fulfill this main objective, a randomized complete block design experiment with three applications at flowering was performed on trees. Of the six tested treatments, only elemental sulfur was able to significantly reduce seed number by 87% compared to the positive control. This is a very novel result because it is the first time that such an effective treatment has been found. The biggest seed number per fruit was obtained for the saccharose treatment. Treatments did not significantly influence yield or fruit quality. These results are entirely consistent with a previous study that evaluated the effect of the same products on pollen tube growth, and they can help to develop new techniques. Nevertheless, more studies are necessary to test, for example, different treatment doses.
Forêt Mediterranéenne, 2010
ABSTRACT Nous avons deja publie plusieurs articles dans notre revue, sur les dommages forestiers ... more ABSTRACT Nous avons deja publie plusieurs articles dans notre revue, sur les dommages forestiers lies ala pollution al'ozone. Dans cette nouvelle etwk, les auteurs nous apportent tks eliments . complementaires quant aux degiits subis par les cembraies du Mercantour, mais aussi des resultats reproduits en chambre de fumigation en Espagne.
Molecular Phylogenetics and Evolution, 2016
Vieraea Folia scientiarum biologicarum canariensium
Parmotrema pseudotinctorum (des Abb.) Hale is a foliose lichen able to colonize large areas on ro... more Parmotrema pseudotinctorum (des Abb.) Hale is a foliose lichen able to colonize large areas on rock surfaces in semiarid and warm localities in the Canary Islands. In this contribution, we investigate the phycobionts of this successful lichen under these extreme environmental conditions using ultrastructural and genetic methodologies. Two populations from La Gomera and La Palma islands were analyzed. After TEM analyses, three algal types were clearly distinguished in intrathalline symbiosis, provisionally named Ph1, Ph2, and Ph3. Two of them (Ph1 and Ph2) were Trebouxia showing a well visible pyrenoid corticolatype the chloroplast thylakoids being very different in both. The type Ph3 could be a taxon included in the genus Asterochloris. Our molecular approach consisted in sequencing two different DNA loci: a portion of the chloroplast psbA gene and nuclear ITS. Sequences of the psbA gene resulted in electrophoretograms showing double peaks when DNA extracted from the whole lichen th...
Symbiosis, 2020
The Canary Islands are famous for their extraordinary biodiversity; however, lichenized algae hav... more The Canary Islands are famous for their extraordinary biodiversity; however, lichenized algae have only been studied partially. Buellia zoharyi is a circum-Mediterranean/Macaronesian species that usually occurs in semi-arid areas of the Mediterranean, but occasionally some interesting communities of this species grow on basaltic lava flows in Lanzarote, Fuerteventura and Tenerife. Those three locations showed similar ecological conditions, but different mean annual temperatures. Here we applied a multidisciplinary approach to describe microalgae diversity from B. zoharyi covering the entire described range of distribution in the Canary Islands. Photobionts were characterized in symbiosis using molecular and microscopic techniques. Different Trebouxia spp. were detected as primary photobiont in each island (Trebouxia cretacea-Fuerteventura, T. asymmetrica-Lanzarote and Trebouxia sp. `arnoldoi´-Tenerife). Coexistence of various Trebouxia spp. within a thallus were detected by using specific primers-PCR. Those three photobionts were isolated and cultured under laboratory conditions. Different phytohormone profiles were obtained in the isolated strains which suggest different internal signalling needs. In addition, we characterized the response of the isolated strains to different temperatures using chlorophyll fluorescence. T. asymmetrica did not modify their Fv/fm values with respect to temperature acclimation. In contrast, Trebouxia sp. `arnoldoi’and T. cretacea were more sensitive to changes in growing temperature decreasing Fv/fm at 17 °C. Our results indicate that B. zoharyi is flexible regarding the photobiont choice depending on the region, and suggest that bioclimatic factors could influence the myco/photobiont association patterns.
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Papers by Francisco José García Breijo
Este trabajo busca que cualquier técnico, con mínimos conocimientos en la protección de cultivos, pueda identificar un hongo y tenga total certeza de su género y, en la mayoría de ocasiones, pueda además identificar su especie simplemente con la ayuda de un microscopio y el presente trabajo.
La identificación del patógeno consta de 8 pasos generales: Observación "in situ", información del agricultor, examen del síndrome, consulta bibliográfica, incubación, aislamiento, reconocimiento y confirmación. Con este trabajo se pretende limitar la consulta bibliográfica al modo de acción
contra el patógeno y que el reconocimiento no sea una tarea de lectura larga y tediosa, sino que con la visualización e identificación de 6 signos previos a la observación microscópica y a otros tres posteriores, un técnico sea capaz de asegurar que patógeno tenemos en el cultivo.
Los síntomas previos a la visualización del microscopio son: Tipo de fructificación, Tipo de tejido sobre el que se desarrolla el patógeno, Color del patógeno, Forma del patógeno, Tipo de unión y si cirra o no.
Los síntomas que deberemos observar durante la visualización en el microscopio son:
Color de las esporas, Número de células de las esporas y Forma de las esporas.
La visualización de estos 9 signos solo nos llevará unos minutos, incluso en el caso de no conocer algún concepto, pues vienen debidamente explicados y dibujados, o fotografiados, en el trabajo.
Además, el trabajo cuenta con una serie de anejos con explicaciones
complementarias para la diagnosis del patógeno en el caso de no contar con microscopio, aunque en este caso se seguirían las pautas normales de diagnosis, que es la de lectura de bibliografía, hasta encontrar la enfermedad que mas se adapta a nuestros signos, pero siempre de la manera más simple y rápida posible. No obstante, de esta manera no será probable llegar al género del hongo afectado, limitándose en ocasiones a la asignación dentro de un grupo de hongos. Esta información nos puede servir en ocasiones, ya que la mayoría de los grupos de hongos se tratan de manera similar, pero no conseguiríamos una determinación exacta únicamente con este trabajo.