Recovery and characterization of a Citrus clementina Hort. ex Tan. 'Clemenules' haploid plant selected to establish the reference whole Citrus genome sequence

<p>Abstract</p> <p>Background</p> <p>In recent years, the development of structural genomics has generated a growing interest in obtaining haploid plants. The use of homozygous lines presents a significant advantage for the accomplishment of sequencing projects. Commercial citrus species are characterized by high heterozygosity, making it difficult to assemble large genome sequences. Thus, the International Citrus Genomic Consortium (ICGC) decided to establish a reference whole citrus genome sequence from a homozygous plant. Due to the existence of important molecular resources and previous success in obtaining haploid clementine plants, haploid clementine was selected as the target for the implementation of the reference whole genome citrus sequence.</p> <p>Results</p> <p>To obtain haploid clementine lines we used the technique of <it>in situ </it>gynogenesis induced by irradiated pollen. Flow cytometry, chromosome counts and SSR marker (Simple Sequence Repeats) analysis facilitated the identification of six different haploid lines (2<it>n </it>= <it>x </it>= 9), one aneuploid line (2<it>n </it>= 2<it>x</it>+4 = 22) and one doubled haploid plant (2<it>n </it>= 2<it>x </it>= 18) of 'Clemenules' clementine. One of the haploids, obtained directly from an original haploid embryo, grew vigorously and produced flowers after four years. This is the first haploid plant of clementine that has bloomed and we have, for the first time, characterized the histology of haploid and diploid flowers of clementine. Additionally a double haploid plant was obtained spontaneously from this haploid line.</p> <p>Conclusion</p> <p>The first haploid plant of 'Clemenules' clementine produced directly by germination of a haploid embryo, which grew vigorously and produced flowers, has been obtained in this work. This haploid line has been selected and it is being used by the ICGC to establish the reference sequence of the nuclear genome of citrus.</p

Findings of intraformational striated pavements in the late carboniferous glacial deposits of the Andean Precordillera, Argentina

One of the most important glacial events in the history of the Earth took place during the Late Paleozoic when large areas of the Gondwana Supercontinent were covered by ice-masses (Crowell, 1978; Hambrey and Harland, 1981; Isbell et al., 2003a,b; Rocha Campos et al., 2008; Fielding et al., 2008; López Gamundí, 2010). Though this glacial event was initially considered a large and unique episode spanning a great part of the Carboniferous and Permian in Gondwana, new geological evidence suggests that the glacial period was not continuous, but rather punctuated by several interglacial events. In this way, López Gamundí (1997) and later Isbell et al. (2003b) divided the Late Paleozoic Ice Age (LPIA) into four major glacial intervals corresponding to the Early Carboniferous (LPIA 1), Late Carboniferous- Early Permian (LPIA 2), Early Permian (LPIA 3) and Late Permian (LPIA 4). This division adequately describes the record of the glacial deposits in Gondwana and allows for the proposal of a general stratigraphy for the glacial deposits demonstrating the existence of low-frequency climatic changes. In this paper we describe two subglacial basal contact surfaces found in the lower part of the Guandacol Formation (Frenguelli, 1944; Cuerda, 1965) in the Central Precordillera (northwestern Argentina). The Guandacol Formation is well known for containing glacial deposits, including diamictites and resedimented diamictites at the lower third of the unit (Limarino et al., 2006; Marenssi et al., 2002; Marenssi et al., 2005). According to paleontological (palynological) information, and some radiometric dating, the age of the glacial deposits is Late Visean- Early Bashkirian and therefore fits into the LPIA 2 interval of Isbell et al. (2003b)

"Safor" Mandarin: A New Citrus Mid-late Triploid Hybrid

World mandarin production rose from 18.3 million tons to 27.9 million tons between the years 2000 and 2007 (FAO, Food and Agriculture Organization, 2009). In Spain, 87% of mandarin production in the last 5 years has been destined to the fresh fruit market (Intercitrus, Interprofessional Citrícola Española, 2008), which demands high-quality, seedless fruits throughout the marketing season. Therefore, the production of seedless varieties is very important. Triploid plants are generally considered an evolutionary dead end, because they generally give rise to aneuploid gametes with very low fertility (Otto and Whitton, 2000). Predominantly trivalent and a high number of bivalent and univalent associations are formed during meiosis of citrus triploid hybrids (Frost and Soost, 1968). Moreover, abortion of the megasporogenesis in the period between the embryo-sac first divisions and the fecundated egg cell is common (Fatta Del Bosco et al., 1992). For this reason, citrus triploid hybrids are generally sterile, although they can occasionally produce fruits with very few seeds and induce seed formation in fruits of other cultivars. Citrus triploid hybrids can be obtained by means of 2x × 2x hybridizations through the production of unreduced gametes by the female parent (Esen and Soost, 1971). The frequency of unreduced gamete formation depends on the genotype (Esen and Soost, 1971; Luro et al., 2004). Triploid embryos are preferentially found in seeds between one-third and one-sixth smaller than normal seeds and these small seeds generally do not germinate under conventional greenhouse conditions. Embryo rescue from these small seeds is required to reach high germination rates (Navarro et al., 2002). Luro et al. (2004) proposed that Second Division Restitution is the mechanism controlling unreduced gamete formation in clementines, whereas in sweet orange, Chen et al. (2008) proposed First Division Restitution to be the mechanism involved. In these two genetic mechanisms, only one part of the maternal heterozygosity is transmitted to the triploid hybrid and the rate of maternal heterozygosity varies among the loci in relation with the rate of single crossing over between the centromere and a given locus (Ollitrault et al., 2008). Ploidy level determination by histological methods is too laborious for large-scale analyses. However, ploidy level can be accurately determined relatively rapidly in large populations by flow cytometry (Ollitrault and Michaux-Ferriere, 1992). Embryo rescue and flow cytometry are two indispensable techniques for extensive triploid citrus breeding programs. These techniques allow the efficient recovery of plants from embryos contained in small seeds and enable the ploidy level of regenerated plantlets to be determined quickly and easily with just a small piece of leaf while the plants are still in the test tube (Navarro et al., 2002). In Spain, there are numerous problems associated with the production season of mandarin cultivars, which include satsumas [Citrus unshiu (Mak.) Marc.], clementines (C. clementina Hort. ex Tan.), and mandarin hybrids. Satsumas and clementines are traditionally harvested from the beginning of September until mid-February. Satsumas produce seedless fruits because they have sterile pollen and ovules. Clementines, the most widely grown mandarins in Spain, are self-incompatible and also produce seedless fruits if grown in isolation. However, their pollen and ovules are viable, and consequently they are able to pollinate and be pollinated by other sexually compatible cultivars. As a result of the demand for late-season mandarins by international markets, several mid- and late-maturing mandarin hybrids were introduced in Spanish citriculture. These hybrids are self-incompatible, but their pollen and ovules are viable and cross-pollinate with clementines, producing fruits with seeds in both groups of cultivars, which causes substantial economic losses. With a view to solving this problematic situation, a triploid breeding program was started in Spain in 1996. The main objective was to produce new mid- and late-maturing triploid cultivars through sexual hybridization, embryo rescue, and ploidy analysis by flow cytometry (Navarro et al., 2002). Recently we released the late-maturing triploid variety Garbí [(C. clementina × C. tangerina) × (C. reticulata × C. sinensis)] (Aleza et al., 2010), which reaches optimum maturation during the second half of March. This variety of mandarin is replacing ‘Fortune’ mandarin (C. clementina × C. tangerina), which reached a peak production of 300,000 tons but is currently being replaced rapidly as a result of its high susceptibility to Alternaria alternata. Another problem is the low fruit quality of ‘Hernandina’ clementine, our latest maturing clementine, when grafted on ‘Carrizo’ citrange (Citrus sinensis × Poncirus trifoliata), which is by far the most predominant rootstock. Fruit peel deteriorates quickly after mid-January, and in practice, no clementine fruits are available by February. In this article, we describe a new triploid hybrid named ‘Safor’ mandarin [(C. clementina × C. tangerina) × (C. unshiu × C. nobilis)] characterized by its high quality, seedless fruits, and mid-late ripening season

"Garbi" Mandarin: A New Late-maturing Triploid Hybrid

Citrus is the most extensively produced fruit tree crop in the world (FAO, Food and Agriculture Organization, 2009). There are two clearly differentiated markets: fresh fruit and processed juice. In 2007, the main citrus fruit-producing countries were China (17.9%), Brazil (17.8%), the Mediterranean countries (17.1%), and the United States (8.5%) (FAO, Food and Agriculture Organization, 2009). These areas account for more of two-thirds of the total production of citrus fruits. In the Mediterranean area, citrus fruits are primarily produced for the fresh fruit market. Spain is the principal producer in the area with a total planted area of 330,000 ha and a production 6.3 million tons. Seedlessness is one of the most important characteristics for mandarin on the fresh fruit market, because consumers do not accept seeded fruits. Parthenocarpy is an essential trait for seedless fruit production, and this characteristic is present in citrus germplasm. Triploidy gives rise to seedless commercial cultivars. However, triploid plants have very low fertility, are generally sterile, and do not induce seeds in other cultivars by crosspollination (Frost and Soost, 1968). Several methods have been developed to obtain triploid citrus (Navarro et al., 2002; Ollitrault et al., 2008). One exploits natural events of polyploidization such as 2n gametes using embryo rescue and flow cytometry to select triploids in 2x · 2x crosses. Second meiotic division restitution has been proposed for diploid megagametophyte development in clementine (Luro et al., 2004), whereas Chen et al. (2008) proposed first meiotic division restitution in sweet oranges. In Spain, the structure of mandarin cultivars poses several problems. Mandarins include satsumas, clementines, and mandarin hybrids. Satsumas are harvested from the beginning of September until the beginning of November. They are cultivars with a high degree of parthenocarpy and have sterile pollen and ovules. Clementines are the most representative cultivars of mandarin in Spain. They are picked from mid-September until mid-February. They are self-incompatible, but pollen and ovules are viable, being able to pollinate and to be pollinated by other cultivars. Mandarin hybrids, like ‘Nova’ [C. clementina · (C. paradisi · C. tangerina)], ‘Fortune’ (C. clementina · C. tangerina), and ‘Ortanique’ tangor (natural hybrid between mandarin and C. sinensis), were introduced in the Spanish citriculture to cover the demand of late-season mandarins by international markets. They enable the harvesting period to be extended until May. These hybrids are also self-incompatible, but pollen and ovules are viable and cross-pollinate with clementines, producing fruits with seeds in both groups of cultivars. A triploid breeding program has been carried out in Spain since 1996 based on sexual hybridization, embryo rescue, and ploidy analysis by flow cytometry (Navarro et al., 2002). The objective is to produce new high–quality, late-season and seedless triploid mandarin hybrids. In this article, we describe ‘Garbı´’ mandarin, a new triploid hybrid developed within this program characterized by its high-quality, late-season ripening and seedless fruits

Alborea: A New Mid-late Mandarin Triploid Hybrid [(Citrus clementina x C. tangerina) x (C. nobilis x C. deliciosa)]

Citrus is one of the most important fruit crops worldwide, with more than 130 million tons produced in 2017. Mandarins represent 25% of this production (Food and Agriculture Organization, 2018) and are mainly destined for fresh consumption. The Mediterranean area is the most important region for mandarin exports, with 60% of the total volume, and Spain is the leading country. The fresh market demands high-quality, seedless fruit that can be harvested throughout the marketing season. Therefore, mandarin breeding programs worldwide are mainly aimed at obtaining new, seedless, easy-peeling varieties with an attractive fruit color and flavor, and with high organoleptic characteristics (Grosser et al., 2010; Navarro et al., 2015; Rapisarda et al., 2008). The mandarin varietal structure in Spain has several problems. It includes satsumas [Citrus unshiu (Mak.) Marc.], clementines (C. clementina Hort. ex Tan.), and mandarin hybrids. Satsumas are harvested from the end of August to mid November. Their pollen and ovules are not viable, and thus they are seedless. Clementine varieties are the most important group of mandarins in Spain and can be harvested from mid September until the second half of January. They are self-incompatible, but their pollen and ovules are viable and, consequently, they are able to pollinate and be pollinated with other compatible cultivars. ‘Hernandina’ clementine, our latest maturing clementine, is characterized by low fruit quality when grafted onto ‘Carrizo’ citrange [C. sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf.], which is by far the predominant rootstock in our country. Fruit peel deteriorates quickly after mid January, and in practice no clementine fruit is available in the second half of January. Mandarin hybrids, such as ‘Nova’ [C. clementina × (C. paradisi Macf. × C. tangerina Hort. Ex Tan.)], ‘Fortune’ (C. clementina × ?), ‘Murcott’ (C. reticulata Blanco × C. sinensis), and ‘Ortanique’ (natural hybrid between mandarin and C. sinensis), were introduced to our citriculture to cover the demand of late-maturing mandarins by international markets. These cultivars are self-incompatible, but their pollen and ovules are viable and they cross-pollinate with clementines, producing seedy fruit in both groups of mandarins. In addition, some late mandarin hybrids, such as ‘Fortune’, ‘Nova’, and ‘Murcott’, are susceptible to Alternaria alternata fungus, which reduces production and depreciates the fruit commercially for the fresh-fruit market. This fungus has forced the top-grafting of trees of these susceptible cultivars, particularly ‘Fortune’, and during the past few decades there has been a decrease in late-mandarin plantations and an increase in clementine plantings, mainly ‘Clemenules’. This has created an imbalance between production and market demand that has caused a drastic reduction in prices for the growers such that, in many cases, they cannot even sell their products. As a consequence of excessive clementine production, a lot of growers decided to cultivate other late mandarin cultivars, especially ‘Nadorcott’ [(C. reticulata × C. sinensis) × ?], ‘Tango’ (irradiated variety from ‘Nadorcott’ mandarin), and ‘Orri’ (irradiated variety from ‘Orah’ mandarin) and, more recently, ‘Spring Sunshine’ (irradiated variety from ‘Murcott’ mandarin), which is susceptible to Alternaria. These varieties cover the period from February to the end of April and are managed by different private companies that limit the number of plants or the cultivated area, and also impose high royalties that, in many cases, are difficult for growers to pay. Under this scenario, the recovery of a new, high-quality seedless mandarin cultivar that matures from mid December until the end of January, when there are no other high-quality mandarins in the market, and that is resistant to Alternaria is a very important objective for our citriculture. In 1995, a triploid breeding program was started at the Instituto Valenciano de Investigaciones Agrarias (IVIA) with the objective of producing new mid- and late-maturing triploid cultivars resistant to A. alternata fungus through sexual hybridization, embryo rescue, and ploidy analysis by flow cytometry (Navarro et al., 2015). Triploid plants generally produce aneuploid gametes, thus leading to very low fertility of their pollen and ovules (Otto and Whitton, 2000). For this reason, citrus triploid hybrids can be considered sterile, producing seedless fruit, and do not induce seed formation in other varieties by cross-pollination, even in the presence of bees (Navarro et al., 2015). A routine strategy exploited for triploid citrus breeding is spontaneous female unreduced gamete formation in diploid × diploid crosses (Aleza et al., 2012; Cuenca et al., 2011, 2015), where triploid hybrids arise usually from the union of an unreduced megagametophyte formed through a second-division restitution mechanism with a haploid pollen (Cameron and Frost 1968; Cuenca et al., 2011; 2015; Esen and Soost 1971, 1973; Geraci et al., 1975; Luro et al., 2004). Triploid embryos are predominantly found in small seeds, which generally do not germinate in greenhouse conditions. Thus, embryo rescue from these small seeds is required to reach high germination rates (Aleza et al., 2010b). In addition, ploidy level determination by flow cytometry is also required in extensive triploid citrus breeding programs (Aleza et al., 2012). From this program, the mid- to late-maturing triploid varieties ‘Garbı’ [(C. clementina × C. tangerine) × (C. reticulata × C. sinensis)] (Aleza et al., 2010a) and ‘Safor’ [(C. clementina × C. tangerina) × (C. unshiu × C. nobilis Lour.)] (Cuenca et al., 2010) were released, with more than 600,000 plants commercialized until 2018. We describe a new triploid hybrid named ‘Alborea’ mandarin [(C. clementina × C. tangerina) × (C. nobilis × C. deliciosa Ten.)] that is resistant to Alternaria alternata and characterized by the production of high-quality, seedless fruit that can be harvested from mid-December until the end of January

Scientific dissemination in the Instituto Español de Oceanografía (IEO): Best practices in recent years

There is a growing interest and obligations to bring the results of scientific research closer to society. In this sense, the Instituto Español de Oceanografía (IEO, CSIC) has acquired in recent years an institutional commitment with the scientific dissemination, carrying out some projects on this topic. The objective of these projects is to visualize and value their research and results in different formats increasing the scientific culture of society that demand and financed most of public research. In the present work four successful initiatives or projects are presented. Diversimar project is a citizen science tool for the observation of the marine and fishing biodiversity of Galicia and the Cantabrian Sea. Mar interior project brings activity of IEO to society with face-to-face conferences and workshops. Planet Tuna project combines science with art through an online platform to enhance the scientific knowledge of tuna and other big pelagics for their sustainability. To end, the interactive book “45 days on the Flemish Cap Bank” spreads the technical and human effort of an oceanographic survey that remains behind the fisheries management developed by the IEO. The objective of the present study is to make visible and put in value these projects and serve as inspiration.Versión del edito

Effect of a Field-Source Mixture of Citrus Viroids on the Performance of Nules; Clementine and Navelina; Sweet Orange Trees Grafted on Carrizo Citrange

A field-source mixture of citrus viroids was characterized and shown to contain Citrus exocortis viroid (CEVd), Hop stunt viroid (HSVd), Citrus bent leaf viroid (CBLVd), and Citrus dwarfing viroid (CDVd). Sequencing results showed that: (i) CEVd contained the P(L) and P(R) characteristic of class A variants; (ii) HSVd was a noncachexia variant; (iii) CBLVd was related to CVd-Ia variants; (iv) CDVd was a mixture of two types (CVd-IIIa and CVd-IIIb) of variants. The presence of the same type of variants in inoculated clementine (Citrus clementina &#39;Nules&#39;) and sweet orange (C. sinensis &#39;Navelina&#39;) trees on Carrizo citrange (Poncirus trifoliata x C. sinensis) rootstocks was confirmed. The effect of infection was determined by assessing the performance of infected and noninfected trees growing in the field. Infection resulted in small trees with reduced canopy, yielding a reduced crop. Fruit characteristics were also affected: (i) clementine and sweet orange fruits from infected trees were larger than those from noninfected trees; (ii) clementine fruits from infected trees differed in shape from those of noninfected trees; (iii) sweet orange fruits from infected trees had maturity indexes and juice contents higher than those from noninfected trees; (iv) in both species, the density of the juice, the amount of soluble solids, and the acidity of the fruits from infected trees were lower than those of fruits from noninfected trees. Infected trees had a poorly developed root system with fibrous roots containing fewer amyloplasts than noninfected trees. The results of an in vitro assay on the induction and development of roots in cultured explants are discussed

Changes in resilience in students of occupational therapy after their first exposure to practice placement education

Introduction: Resilience is a multidimensional and dynamic construct associated with positive growth and the capacity to transform stressful and negative factors into opportunities of personal development and self-improvement when faced with difficult experiences. The resilience process of each individual integrates multiple analysis levels, which range from genetic-environmental interactions to a complex process of adaptation between the individual and his/her family, friends, co-workers, society, and culture. Objective: To determine whether resilience improves in students of occupational therapy when exposed for the first time to practice placement education. Methodology: Quasi-experimental, prospective, observational, multi-center study with a sample composed of students from the Degree of Occupational Therapy of the public universities of Málaga (UMA) and Castilla-La Mancha (UCLM) (Spain). Two weeks prior to the beginning of the practice education period, the participants completed a questionnaire that included sociodemographic data and the area of their internships. They were also given the Spanish version of the Connor-Davidson's resilience scale (CD-RISC). All these instruments were also completed 1 week after the end of the clinical practice. Results: There were statistically significant differences between the variables that make up resilience and the different internship areas. On the other hand, there was a significant improvement of global resilience after the clinical practice period, in both women (13.85 points; p < 0.001) and men (7.72 points; p < 0.035), when the internship area was not considered. Conclusions: The results show that resilient students are more optimistic and work to improve a situation beyond doing simply what is expected of them, knowing how to control their feelings. This is beneficial for students in practice education, since, during these, they face difficult situations that require a resilient pattern, which helps reduce stress and the burnout syndrome