Baroja Fernández, Edurne

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https://academica-e.unavarra.es/handle/2454/48667

Last Name

Baroja Fernández

First Name

Edurne

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Producción Agraria

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0000-0003-0049-6045

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1602

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Open Access
Sucrose synthase activity in the sus1/sus2/sus3/sus4 Arabidopsis mutant is sufficient to support normal cellulose and starch production
(National Academy of Sciences, 2011) Baroja Fernández, Edurne; Muñoz Pérez, Francisco José; Li, Jun; Bahaji, Abdellatif; Almagro Zabalza, Goizeder; Montero Macarro, Manuel; Etxeberria, Ed; Hidalgo Cruz, Maite; Sesma Pascual, María Teresa; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Sucrose synthase (SUS) catalyzes the reversible conversion of sucrose and a nucleoside diphosphate into the corresponding nucleoside diphosphate-glucose and fructose. In Arabidopsis, a multigene family encodes six SUS (SUS1-6) isoforms. The involvement of SUS in the synthesis of UDP-glucose and ADP-glucose linked to Arabidopsis cellulose and starch biosynthesis, respectively, has been questioned by Barratt et al. [(2009) Proc Natl Acad Sci USA 106:13124–13129], who showed that (i) SUS activity in wild type (WT) leaves is too low to account for normal rate of starch accumulation in Arabidopsis, and (ii) different organs of the sus1/sus2/sus3/sus4 SUS mutant impaired in SUS activity accumulate WT levels of ADP-glucose, UDP-glucose, cellulose and starch. However, these authors assayed SUS activity under unfavorable pH conditions for the reaction. By using favorable pH conditions for assaying SUS activity, in this work we show that SUS activity in the cleavage direction is sufficient to support normal rate of starch accumulation in WT leaves. We also demonstrate that sus1/sus2/sus3/sus4 leaves display WT SUS5 and SUS6 expression levels, whereas leaves of the sus5/sus6 mutant display WT SUS1–4 expression levels. Furthermore, we show that SUS activity in leaves and stems of the sus1/sus2/sus3/sus4 and sus5/sus6 plants is ~85% of that of WT leaves, which can support normal cellulose and starch biosynthesis. The overall data disprove Barratt et al. (2009) claims, and are consistent with the possible involvement of SUS in cellulose and starch biosynthesis in Arabidopsis.
Open Access
A cAMP/CRP-controlled mechanism for the incorporation of extracellular ADP-glucose in Escherichia coli involving NupC and NupG nucleoside transporters
(Nature Research, 2018) Almagro Zabalza, Goizeder; Viale Bailone, Alejandro M.; Montero Macarro, Manuel; Muñoz Pérez, Francisco José; Baroja Fernández, Edurne; Mori, Hirotada; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
ADP-glucose is the precursor of glycogen biosynthesis in bacteria, and a compound abundant in the starchy plant organs ingested by many mammals. Here we show that the enteric species Escherichia coli is capable of scavenging exogenous ADP-glucose for use as a glycosyl donor in glycogen biosynthesis and feed the adenine nucleotide pool. To unravel the molecular mechanisms involved in this process, we screened the E. coli single-gene deletion mutants of the Keio collection for glycogen content in ADP-glucose-containing culture medium. In comparison to wild-type (WT) cells, individual ∆nupC and ∆nupG mutants lacking the cAMP/CRP responsive inner-membrane nucleoside transporters NupC and NupG displayed reduced glycogen contents and slow ADP-glucose incorporation. In concordance, ∆cya and ∆crp mutants accumulated low levels of glycogen and slowly incorporated ADP-glucose. Two-thirds of the glycogen-excess mutants identified during screening lacked functions that underlie envelope biogenesis and integrity, including the RpoE specific RseA anti-sigma factor. These mutants exhibited higher ADP-glucose uptake than WT cells. The incorporation of either ∆crp, ∆nupG or ∆nupC null alleles sharply reduced the ADP-glucose incorporation and glycogen content initially witnessed in ∆rseA cells. Overall, the data showed that E. coli incorporates extracellular ADP-glucose through a cAMP/CRP-regulated process involving the NupC and NupG nucleoside transporters that is facilitated under envelope stress conditions.
Open Access
Ectopic expression of the AtCDF1 transcription factor in potato enhances tuber starch and amino acid contents and yield under open field conditions
(Frontiers Media, 2023) Carrillo, Laura; Baroja Fernández, Edurne; Renau Morata, Begoña; Muñoz Pérez, Francisco José; Canales, Javier; Ciordia, Sergio; Yang, Lu; Sánchez López, Ángela María; Nebauer, Sergio G.; Ceballos, Mar G.; Vicente-Carbajosa, Jesús; Molina, Rosa V.; Pozueta Romero, Javier; Medina, Joaquín; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
Introduction: cycling Dof transcription factors (CDFs) have been involved in different aspects of plant growth and development. In Arabidopsis and tomato, one member of this family (CDF1) has recently been associated with the regulation of primary metabolism and abiotic stress responses, but their roles in crop production under open field conditions remain unknown. Methods: in this study, we compared the growth, and tuber yield and composition of plants ectopically expressing the CDF1 gene from Arabidopsis under the control of the 35S promoter with wild-type (WT) potato plants cultured in growth chamber and open field conditions. Results: in growth chambers, the 35S::AtCDF1 plants showed a greater tuber yield than the WT by increasing the biomass partition for tuber development. Under field conditions, the ectopic expression of CDF1 also promoted the sink strength of the tubers, since 35S::AtCDF1 plants exhibited significant increases in tuber size and weight resulting in higher tuber yield. A metabolomic analysis revealed that tubers of 35S::AtCDF1 plants cultured under open field conditions accumulated higher levels of glucose, starch and amino acids than WT tubers. A comparative proteomic analysis of tubers of 35S::AtCDF1 and WT plants cultured under open field conditions revealed that these changes can be accounted for changes in the expression of proteins involved in energy production and different aspects of C and N metabolism. Discussion: The results from this study advance our collective understanding of the role of CDFs and are of great interest for the purposes of improving the yield and breeding of crop plants.
Open Access
Elevated CO2 improved the growth of a double nitrate reductase defective mutant of Arabidopsis thaliana: the importance of maintaining a high energy status
(Elsevier, 2017) Jáuregui Mosquera, Iván; Aparicio Tejo, Pedro María; Baroja Fernández, Edurne; Ávila, Concepción; Aranjuelo Michelena, Iker; Natura Ingurunearen Zientziak; Ciencias del Medio Natural; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
Impairments in leaf nitrogen (N) assimilation in C3 plants have been identified as processes conditioning photosynthesis under elevated [CO2], especially when N is supplied as nitrate. Leaf N status is usually improved under ammonium nutrition and elevated [CO2]. However, ammonium fertilization is usually accompanied by the appearance of oxidative stress symptoms, which constrains plant development. To understand how the limitations of direct fertilization with ammonium (growth reduction attributed to ammonium toxicity) can be overcome, the effects of elevated [CO2] (800 ppm) exposure were studied in the Arabidopsis thaliana double nitrate reductase defective mutant, nia1-1/chl3-5 (which preferentially assimilates ammonium as its nitrogen source). Analysis of the physiology, metabolites and gene expression was carried out in roots and shoot organs. Our study clearly showed that elevated [CO2] improved the inhibited phenotype of the nitrate reductase double mutant. Both the photosynthetic rates and the leaf N content of the NR mutant under elevated CO2 were similar to wild type plants. The growth of the nitrate reductase mutant was linked to its ability to overcome ammonium-associated photoinhibition processes at 800 ppm [CO2]. More specifically: (i) the capacity of NR mutants to equilibrate energy availability, as reflected by the electron transport equilibrium reached (photosynthesis, photorespiration and respiration), (ii) as well as by the upregulation of genes involved in stress tolerance were identified as the processes involved in the improved performance of NR mutants.
Open Access
Arabidopsis responds to Alternaria alternata volatiles by triggering pPG-independent mechanisms
(American Society of Plant Biologists, 2016) Sánchez López, Ángela María; Bahaji, Abdellatif; Diego, Nuria de; Baslam, Marouane; Li, Jun; Muñoz Pérez, Francisco José; Almagro Zabalza, Goizeder; García Gómez, Pablo; Ameztoy del Amo, Kinia; Ricarte Bermejo, Adriana; Novák, Ondrej; Humplik, Jan F.; Spíchal, Lukás; Dolezal, Karel; Ciordia, Sergio; Mena, María Carmen; Navajas, Rosana; Baroja Fernández, Edurne; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua (IIM010491.RI1); Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Volatile compounds (VCs) emitted by phylogenetically diverse microorganisms (including plant pathogens and microbes that do not normally interact mutualistically with plants) promote photosynthesis, growth, and the accumulation of high levels of starch in leaves through cytokinin (CK)-regulated processes. In Arabidopsis (Arabidopsis thaliana) plants not exposed to VCs, plastidic phosphoglucose isomerase (pPGI) acts as an important determinant of photosynthesis and growth, likely as a consequence of its involvement in the synthesis of plastidic CKs in roots. Moreover, this enzyme plays an important role in connecting the Calvin- Benson cycle with the starch biosynthetic pathway in leaves. To elucidate the mechanisms involved in the responses of plants to microbial VCs and to investigate the extent of pPGI involvement, we characterized pPGI-null pgi1-2 Arabidopsis plants cultured in the presence or absence of VCs emitted by Alternaria alternata. We found that volatile emissions from this fungal phytopathogen promote growth, photosynthesis, and the accumulation of plastidic CKs in pgi1-2 leaves. Notably, the mesophyll cells of pgi1-2 leaves accumulated exceptionally high levels of starch following VC exposure. Proteomic analyses revealed that VCs promote global changes in the expression of proteins involved in photosynthesis, starch metabolism, and growth that can account for the observed responses in pgi1-2 plants. The overall data show that Arabidopsis plants can respond to VCs emitted by phytopathogenic microorganisms by triggering pPGI-independent mechanisms.
Open Access
Systematic production of inactivating and non-inactivating suppressor mutations at the relA locus that compensate the detrimental effects of complete spoT loss and affect glycogen content in Escherichia coli
(Public Library of Science, 2014) Montero Macarro, Manuel; Rahimpour, Mehdi; Viale Bailone, Alejandro M.; Almagro Zabalza, Goizeder; Eydallin, Gustavo; Sevilla, Ángel; Cánovas, Manuel; Bernal, Cristina; Lozano, Ana Belén; Muñoz Pérez, Francisco José; Baroja Fernández, Edurne; Bahaji, Abdellatif; Mori, Hirotada; Codoñer, Francisco M.; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In Escherichia coli, ppGpp is a major determinant of growth and glycogen accumulation. Levels of this signaling nucleotide are controlled by the balanced activities of the ppGpp RelA synthetase and the dual-function hydrolase/synthetase SpoT. Here we report the construction of spoT null (DspoT) mutants obtained by transducing a DspoT allele from DrelADspoT double mutants into relA+ cells. Iodine staining of randomly selected transductants cultured on a rich complex medium revealed differences in glycogen content among them. Sequence and biochemical analyses of 8 DspoT clones displaying glycogen-deficient phenotypes revealed different inactivating mutations in relA and no detectable ppGpp when cells were cultured on a rich complex medium. Remarkably, although the co-existence of DspoT with relA proficient alleles has generally been considered synthetically lethal, we found that 11 DspoT clones displaying high glycogen phenotypes possessed relA mutant alleles with non-inactivating mutations that encoded stable RelA proteins and ppGpp contents reaching 45–85% of those of wild type cells. None of the DspoT clones, however, could grow on M9-glucose minimal medium. Both Sanger sequencing of specific genes and high-throughput genome sequencing of the DspoT clones revealed that suppressor mutations were restricted to the relA locus. The overall results (a) defined in around 4 nmoles ppGpp/g dry weight the threshold cellular levels that suffice to trigger net glycogen accumulation, (b) showed that mutations in relA, but not necessarily inactivating mutations, can be selected to compensate total SpoT function(s) loss, and (c) provided useful tools for studies of the in vivo regulation of E. coli RelA ppGpp synthetase.
Open Access
Adenosine diphosphate glucose pyrophosphatase: a plastidial phosphodiesterase that prevents starch biosynthesis
(National Academy of Sciences, 2000) Rodríguez López, Milagros; Baroja Fernández, Edurne; Zandueta Criado, Aitor; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
A distinct phosphodiesterasic activity (EC 3.1.4) was found in both mono- and dicotyledonous plants that catalyzes the hydrolytic breakdown of ADPglucose (ADPG) to produce equimolar amounts of glucose-1-phosphate and AMP. The enzyme responsible for this activity, referred to as ADPG pyrophosphatase (AGPPase), was purified over 1,100-fold from barley leaves and subjected to biochemical characterization. The calculated Keq* (modified equilibrium constant) value for the ADPG hydrolytic reaction at pH 7.0 and 25°C is 110, and its standard-state free-energy change value (DG*) is 22.9 kcalymol (1 kcal 5 4.18 kJ). Kinetic analyses showed that, although AGPPase can hydrolyze several low-molecular weight phosphodiester bond-containing compounds, ADPG proved to be the best substrate (Km 5 0.5 mM). Pi and phosphorylated compounds such as 3-phosphoglycerate, PPi, ATP, ADP, NADP1, and AMP are inhibitors of AGPPase. Subcellular localization studies revealed that AGPPase is localized exclusively in the plastidial compartment of cultured cells of sycamore (Acer pseudoplatanus L.), whereas it occurs both inside and outside the plastid in barley endosperm. In this paper, evidence is presented that shows that AGPPase, whose activity declines concomitantly with the accumulation of starch during development of sink organs, competes with starch synthase (ADPG:1,4-a-D-glucan 4-a- D-glucosyltransferase; EC 2.4.1.21) for ADPG, thus markedly blocking the starch biosynthesis.
Open Access
Influence of crop load on the expression patterns of starch metabolism genes in alternate-bearing citrus trees
(Elsevier, 2014) Nebauer, Sergio G.; Renau Morata, Begoña; Lluch, Yolanda; Baroja Fernández, Edurne; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
The fruit is the main sink organ in Citrus and captures almost all available photoassimilates during its development. Consequently, carbohydrate partitioning and starch content depend on the crop load of Citrus trees. Nevertheless, little is known about the mechanisms controlling the starch metabolism at the tree level in relation to presence of fruit. The aim of this study was to find the relation between the seasonal variation of expression and activity of the genes involved in carbon metabolism and the partition and allocation of carbohydrates in ‘Salustiana’ sweet orange trees with different crop loads. Metabolisable carbohydrates, and the expression and activity of the enzymes involved in sucrose and starch metabolism, including sucrose transport, were determined during the year in the roots and leaves of 40-year-old trees bearing heavy crop loads ('on' trees) and trees with almost no fruits ('off' trees). Fruit altered photoassimilate partitioning in trees. Sucrose content tended to be constant in roots and leaves, and surplus fixed carbon is channeled to starch production. Differences between 'on' and 'off' trees in starch content can be explained by differences in ADP-glucose pyrophosphorylase (AGPP) expression/activity and a-amylase activity which varies depending on crop load. The observed relation of AGPP and UGPP (UDP-glucose pyrophosphorylase) is noteworthy and indicates a direct link between sucrose and starch synthesis. Furthermore, different roles for sucrose transporter SUT1 and SUT2 have been proposed. Variation in soluble sugars content cannot explain the differences in gene expression between the 'on' and 'off' trees. A still unknown signal from fruit should be responsible for this control.
Open Access
Cell-free microbial culture filtrates as candidate biostimulants to enhance plant growth and yield and activate soil- and plant-associated beneficial microbiota
(Frontiers Media, 2022) León Morcillo, Rafael Jorge; Baroja Fernández, Edurne; López-Serrano, Lidia; Leal-López, Jesús; Muñoz Pérez, Francisco José; Bahaji, Abdellatif; Férez-Gómez, Alberto; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
In this work we compiled information on current and emerging microbial-based fertilization practices, especially the use of cell-free microbial culture filtrates (CFs), to promote plant growth, yield and stress tolerance, and their effects on plant-associated beneficial microbiota. In addition, we identified limitations to bring microbial CFs to the market as biostimulants. In nature, plants act as metaorganisms, hosting microorganisms that communicate with the plants by exchanging semiochemicals through the phytosphere. Such symbiotic interactions are of high importance not only for plant yield and quality, but also for functioning of the soil microbiota. One environmentally sustainable practice to increasing crop productivity and/or protecting plants from (a)biotic stresses while reducing the excessive and inappropriate application of agrochemicals is based on the use of inoculants of beneficial microorganisms. However, this technology has a number of limitations, including inconsistencies in the field, specific growth requirements and host compatibility. Beneficial microorganisms release diffusible substances that promote plant growth and enhance yield and stress tolerance. Recently, evidence has been provided that this capacity also extends to phytopathogens. Consistently, soil application of microbial cell-free culture filtrates (CFs) has been found to promote growth and enhance the yield of horticultural crops. Recent studies have shown that the response of plants to soil application of microbial CFs is associated with strong proliferation of the resident beneficial soil microbiota. Therefore, the use of microbial CFs to enhance both crop yield and stress tolerance, and to activate beneficial soil microbiota could be a safe, efficient and environmentally friendly approach to minimize shortfalls related to the technology of microbial inoculation. In this review, we compile information on microbial CFs and the main constituents (especially volatile compounds) that promote plant growth, yield and stress tolerance, and their effects on plant-associated beneficial microbiota. In addition, we identify challenges and limitations for their use as biostimulants to bring them to the market and we propose remedial actions and give suggestions for future work.
Open Access
Enhanced yield of pepper plants promoted by soil application of volatiles from cell-free fungal culture filtrates is associated with activation of the beneficial soil microbiota
(Frontiers Media, 2021) Baroja Fernández, Edurne; Almagro Zabalza, Goizeder; Sánchez López, Ángela María; Bahaji, Abdellatif; Gámez Arcas, Samuel; Diego, Nuria de; Dolezal, Karel; Muñoz Pérez, Francisco José; Climent Sanz, Eric; Pozueta Romero, Javier; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua
Plants communicate with microorganisms by exchanging chemical signals throughout the phytosphere. Such interactions are important not only for plant productivity and fitness, but also for terrestrial ecosystem functioning. It is known that beneficial microorganisms emit diffusible substances including volatile organic compounds (VOCs) that promote growth. Consistently, soil application of cell-free culture filtrates (CF) of beneficial soil and plant-associated microorganisms enhances plant growth and yield. However, how this treatment acts in plants and whether it alters the resident soil microbiota, are largely unknown. In this work we characterized the responses of pepper (Capsicum annuum L.) plants cultured under both greenhouse and open field conditions and of soil microbiota to soil application of CFs of beneficial and phytopathogenic fungi. To evaluate the contribution of VOCs occurring in the CFs to these responses, we characterized the responses of plants and of soil microbiota to application of distillates (DE) of the fungal CFs. CFs and their respective DEs contained the same potentially biogenic VOCs, and application of these extracts enhanced root growth and fruit yield, and altered the nutritional characteristics of fruits. High-throughput amplicon sequencing of bacterial 16S and fungal ITS rRNA genes of the soil microbiota revealed that the CF and DE treatments altered the microbial community compositions, and led to strong enrichment of the populations of the same beneficial bacterial and fungal taxa. Our findings show that CFs of both beneficial and phytopathogenic fungi can be used as biostimulants, and provide evidence that VOCs occurring in the fungal CFs act as mediators of the plants’ responses to soil application of fungal CFs through stimulation of the beneficial soil microbiota.