Caracterización molecular y funcional del gen PATHOGEN AND CIRCADIAN CONTROLLED 1 (PCC1) en Arabidopsis thaliana

Las plantas son capaces de modificar los patrones de desarrollo tras percibir ciertos tipos de estrés. En Arabidopsis, se identificó PCC1 como un regulador positivo de la transición floral en respuesta al estrés generado por irradiación con luz UV-C. El análisis de plantas transgénicas pPCC1::GUS muestra que PCC1 se expresa durante los primeros días de desarrollo en estomas y haces vasculares de cotiledones. En hojas verdaderas en formación se detecta tinción GUS en su parte basal, incluyendo los haces vasculares, y se va extendiendo completamente a toda la superficie de hojas completamente formadas. Líneas que expresan construcciones de RNAi para PCC1 (iPCC1) presentan reducidos niveles de FT y, consecuentemente, una floración más tardía. El mecanismo por el cual PCC1 podría regular la transición floral parece estar relacionado con alteraciones en la transmisión de la señal por luz. Concomitantemente, las plantas iPCC1 muestran fenotipos parcialmente escotomorfogénicos en los distintos tipos de luz ensayados de forma independiente de la acumulación y señalización de GAs. El transcriptoma diferencial de plantas iPCC1 versus plantas silvestres muestra una clara implicación de PCC1 en procesos relacionados con defensa. De acuerdo con este hecho, hemos observado que las plantas iPCC1 son más susceptibles a la infección con el oomiceto hemi-biotrofo Phytophtora brassicae y más resistentes al hongo necrotrofo Botrytis cinerea. Además, las líneas iPCC1 presentan una regulación al alza de genes de respuesta a ABA, y una mayor sensibilidad a esta fitohormona para los distintos fenotipos analizados. Finalmente, entre los genes alterados en las líneas iPCC1 se observa una sobrerepresentación de genes implicados en el metabolismo y en el transporte de lípidos. La pérdida de función de PCC1 conlleva una reducción del 70% en los niveles de fosfatidilinositol, y en menor medida de otros tipos de lípidos polares como la fosfatidilserina o la fosfatidilcolina. Además, el análisis de la composición de ácidos grasos de cada tipo de lípidos polares revela un mayor grado de insaturación de sus cadenas laterales, fundamentalmente en la fosfatidilserina y el fosfatidilinositol. PCC1 es una proteína asociada a la membrana plasmática por su extremo carboxiterminal, el cual es responsable además de la formación de homodímeros. Aunque queda por dilucidiar los mecanismos por los cuales PCC1 puede regular procesos tan dispares molecularmente como la respuesta a patógenos y la transición floral, hemos observado que PCC1 interacciona con la subunidad CSN5 del signalosoma (CSN), lo que sugiere que PCC1 podría actuar como un regulador de la función de CSN, y en última instancia, de la degradación de proteínas por ubiquitinación.Mir Moreno, R. (2013). Caracterización molecular y funcional del gen PATHOGEN AND CIRCADIAN CONTROLLED 1 (PCC1) en Arabidopsis thaliana [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/29751TESI

Doubled haploids in eggplant

[EN] This review compiles the most relevant advances made in the production of doubled haploid plants in eggplant, the application of doubled haploid lines in breeding programs, and the future perspectives for the development of alternative technologies for doubled haploid generation in this species. Eggplant is a solanaceous crop cultivated worldwide for its edible fruit. Eggplant breeding programs are mainly aimed to the generation of F1 hybrids by crossing two highly homozygous, pure lines, which are traditionally obtained upon several self crossing generations, which is an expensive and time consuming process. Alternatively, fully homozygous, doubled haploid (DH) individuals can be induced from haploid cells of the germ line in a single generation. Several attempts have been made to develop protocols to produce eggplant DHs principally using anther culture and isolated microspore culture. Eggplant could be considered a moderately recalcitrant species in terms of ability for DH production. Anther culture stands nowadays as the most valuable technology to obtain eggplant DHs. However, the theoretical possibility of having plants regenerated from somatic tissues of the anther walls cannot be ruled out. For this reason, the use of isolated microspores is recommended when possible. This approach still has room for improvement, but it is largely genotype-dependent. In this review, we compile the most relevant advances made in DH production in eggplant, their application to breeding programs, and the future perspectives for the development of other, less genotype-dependent, DH technologies.This research was funded by the Valencian Government, grant number CDEIGENT 2018/023 to RMM and by the Spanish MICINN, grant number PID2020-115763RB-I00 to JMSS. ACS is the recipient of a predoctoral contract from the FPU program of the Spanish Government.Mir Moreno, R.; Calabuig-Serna, A.; Seguí-Simarro, JM. (2021). Doubled haploids in eggplant. Biology. 10(7):1-16. https://doi.org/10.3390/biology10070685S11610

Sulfide fluxes in a microbial mat from the Ebro Delta, Spain

The sulfur cycle of Ebro Delta microbial mats was studied in order to determine sulfide production and sulfide consumption. Vertical distribution of two major functional groups involved in the sulfur cycle, anoxygenic phototrophic bacteria and dissimilatory sulfate-reducing bacteria (SRB), was also studied. The former reached up to 2.2 ×108 cfu cm-3 sediment in the purple layer, and the latter reached about 1.8×105 SRB cm-3 sediment in the black layer. From the changes in sulfide concentrations under light-dark cycles it can be inferred that the rate of H2S production was 6.2 μmol H2S cm-3 day-1 at 2.6 mm, and 7.6 μmol H2S cm-3 day-1 at 6 mm. Furthermore, sulfide consumption was also assessed, determining rates of 0.04, 0.13 and 0.005 mmol l-1 of sulfide oxidized at depths of 2.6, 3 and 6 mm, respectively

Analysis of transient behavior during starter compensated of asynchronous motors propellant in low-powered electric boats

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Distribution of phototrophic populations and primary production in a microbial mat from the Ebro Delta, Spain

Microbial mats arising in the sand flats of the Ebro Delta (Tarragona, Spain) were investigated during the summer season, when the community was highly developed. These mats are composed of three pigmented layers of phototrophic organisms, an upper brown layer mainly composed of Lyngbya aestuarii and diatoms, an intermediate green layer of the cyanobacterium Microcoleus chthonoplastes, and an underlying pink layer of a so-far unidentified purple sulfur bacterium. In the photic zone, oxygenic phototrophs constitute about 58% of total photosynthetic biomass, measured as biovolume, and anoxygenic phototrophs represent 42%. Diatoms constitute 11.8% of the oxygenic biomass, M. chthonoplastes 61.2%, and L. aestuarii and coccoid cyanobacteria 20.6 and 6.4%, respectively. In this laminated community, organic matter has an autochthonous origin, and photosynthesis is the most important source of organic carbon. Oxygen production reaches up to 27.2 mmol O2 m–2 h–1, measured at 1000 μE m–2 s–1 light intensity, whereas oxidation of sulfide in the light has been calculated to be 18.6 mmol S m–2 h–1. This amount represents 26% of the total photosynthetic production in terms of photoassimilated carbon, demonstrating the important role of anoxygenic phototrophs as primary producers in the pink layer of Ebro Delta microbial mats. [Int Microbiol 2004; 7(1):19–25

Cell Wall Composition and Structure Define the Developmental Fate of Embryogenic Microspores in Brassica napus

[EN] Microspore cultures generate a heterogeneous population of embryogenic structures that can be grouped into highly embryogenic structures [exine-enclosed (EE) and loose bicellular structures (LBS)] and barely embryogenic structures [compact callus (CC) and loose callus (LC) structures]. Little is known about the factors behind these different responses. In this study we performed a comparative analysis of the composition and architecture of the cell walls of each structure by confocal and quantitative electron microscopy. Each structure presented specific cell wall characteristics that defined their developmental fate. EE and LBS structures, which are responsible for most of the viable embryos, showed a specific profile with thin walls rich in arabinogalactan proteins (AGPs), highly and low methyl-esterified pectin and callose, and a callose-rich subintinal layer not necessarily thick, but with a remarkably high callose concentration. The different profiles of EE and LBS walls support the development as suspensorless and suspensor-bearing embryos, respectively. Conversely, less viable embryogenic structures (LC) presented the thickest walls and the lowest values for almost all of the studied cell wall components. These cell wall properties would be the less favorable for cell proliferation and embryo progression. High levels of highly methyl-esterified pectin are necessary for wall flexibility and growth of highly embryogenic structures. AGPs seem to play a role in cell wall stiffness, possibly due to their putative role as calcium capacitors, explaining the positive relationship between embryogenic potential and calcium levels.This work was supported by grant PID2020-115763RBI00 to JS-S from Spanish MICINN and by a Juan de la Cierva -Incorporacion Fellowship and a Marie Sklodowska-Curie Individual Fellowship (656579) to PC-M. RM holds a CDEIGENT (2018/023) fellowship from Generalitat Valenciana.Camacho-Fernández, C.; Seguí-Simarro, JM.; Mir Moreno, R.; Boutilier, K.; Corral-Martínez, P. (2021). Cell Wall Composition and Structure Define the Developmental Fate of Embryogenic Microspores in Brassica napus. Frontiers in Plant Science. 12:1-16. https://doi.org/10.3389/fpls.2021.7371391161

Pathogen and Circadian Controlled 1 (PCC1) regulates polar lipid content, ABA-related responses, and pathogen defence in Arabidopsis thaliana

Pathogen and Circadian Controlled 1 (PCC1) was previously characterized as a regulator of defence against pathogens and stress-activated transition to flowering. Plants expressing an RNA interference construct for the PCC1 gene (iPCC1 plants) showed a pleiotropic phenotype. They were hypersensitive to abscisic acid (ABA) as shown by reduced germination potential and seedling establishment, as well as reduced stomatal aperture and main root length in ABA-supplemented media. In addition, iPCC1 plants displayed alterations in polar lipid contents and their corresponding fatty acids. Importantly, a significant reduction in the content of phosphatidylinositol (PI) was observed in iPCC1 leaves when compared with wild-type plants. A trend in reduced levels of 18:0 and increased levels of 18:2 and particularly 18:3 was also detected in several classes of polar lipids. The enhanced ABA-mediated responses and the reduced content of PI might be responsible for iPCC1 plants displaying a complex pattern of defence against pathogens of different lifestyles. iPCC1 plants were more susceptible to the hemi-biotrophic oomycete pathogen Phytophthora brassicae and more resistant to the necrotrophic fungal pathogen Botrytis cinerea compared with wild-type plant