Open Access
Split‐root systems applied to the study of the legume‐rhizobial symbiosis: what have we learned?
(Wiley, 2014) Larrainzar Rodríguez, Estíbaliz; Gil Quintana, Erena; Arrese-Igor Sánchez, César; González García, Esther; Marino Bilbao, Daniel; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Split-root system (SRS) approaches allow the differential treatment of separate and independent root systems, while sharing a common aerial part. As such, SRS is a useful tool for the discrimination of systemic (shoot origin) versus local (root/nodule origin) regulation mechanisms. This type of approach is particularly useful when studying the complex regulatory mechanisms governing the symbiosis established between legumes and Rhizobium bacteria. The current work provides an overview of the main insights gained from the application of SRS approaches to understand how nodule number (nodulation autoregulation) and nitrogen fixation are controlled both under non-stressful conditions and in response to a variety of stresses. Nodule number appears to be mainly controlled at the systemic level through a signal which is produced by nodule/root tissue, translocated to the shoot, and transmitted back to the root system, involving shoot Leu-rich repeat receptor-like kinases. In contrast, both local and systemic mechanisms have been shown to operate for the regulation of nitrogenase activity in nodules. Under drought and heavy metal stress, the regulation is mostly local, whereas the application of exogenous nitrogen seems to exert a regulation of nitrogen fixation both at the local and systemic levels.
Open Access
Estudio de prospectiva, análisis y propuesta de participación y colaboración de la Administración Foral de Navarra con las redes, plataformas e iniciativas de ciencia ciudadana
(2016) González García, Esther; Peralta de Andrés, Francisco Javier; Imbert Rodríguez, Bosco; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
El objetivo de este trabajo es analizar las redes y plataformas de ciencia ciudadana existentes con el fin de realizar una propuesta para su implementación en Navarra por parte de la Administración Ambiental; para ello se revisa cómo abordan otras administraciones la ciencia ciudadana a distintos niveles y las posibles formas de participación o colaboración de la Administración.
Open Access
Physiological and biochemical characterization of rootlets response to salt stress in two Medicago truncatula Gaertn. ecotypes
(Japanese Society for Root Research, 2018) Amouri, Adel Amar; González García, Esther; Aoul, Seghir Hadjadj; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Legumes are very important plants both ecologically and agriculturally because they are able to interact symbiotically with rhizobia for biological nitrogen fixation and soil fertilization. Medicago truncatula Gaertn. is an important model legume rich in protein. Salinity represents, today, the major cause of land degradation and crop productivity limitation around the world and affects physiology and metabolism in legumes. In this study, we analyzed the physiological and biochemical responses of rootlets in two contrasting ecotypes of Medicago truncatula (Tru 131, tolerant and Jemalong, sensitive) to different level of NaCl, (68, 102 and 137 mM). Results showed that the tolerant ecotype has a lower water potential than Jemalong. Root protein content of Tru 131 was decreased than Jemalong, this can be explained by accumulation of protein oxidation in the sensitive genotype. Moreover, NaCl increased guaiacol peroxidase activity GPX in rootlets of Tru 131, this enzyme has a protective role against the molecules ROS accumulated during oxidative stress. On the other hand, under salt stress the total content of ascorbate (ASC + DHA) and Glutathione (GSH + GSSG) was increased in the tolerant genotype Tru 131 compared to Jemalong. These results show how the tolerant genotype activate the antioxidative defense system at root level against damages caused by oxidative stress under salinity.
Open Access
Use of recombinant iron-superoxide dismutase as a marker of nitrative stress
(Elservier, 2008-04-20) Larrainzar Rodríguez, Estíbaliz; Urarte Rodríguez, Estíbaliz; Auzmendi, Iñigo; Ariz Arnedo, Idoia; Arrese-Igor Sánchez, César; González García, Esther; Morán Juez, José Fernando; Ciencias del Medio Natural; Natura Ingurunearen Zientziak; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua, 57/2007
Superoxide dismutases (SODs; EC 1.15.1.1) are a group of metalloenzymes which are essential to protect cells under aerobic conditions. In biological systems, it has been reported that SODs and other proteins are susceptible to be attacked by peroxynitrite (ONOO-) which can be originated from the reaction of nitric oxide with superoxide radical. ONOO- is a strong oxidant molecule capable of nitrating peptides and proteins at the phenyl side chain of the tyrosine residues. In the present work, bovine serum albumin (BSA) and recombinant iron¿superoxide dismutase from the plant cowpea (Vu_FeSOD) are used as target molecules to estimate ONOO- production. The method employs the compound SIN-1, which simultaneously generates -NO and O2- in aerobic aqueous solutions. First, assay conditions were optimized incubating BSA with different concentrations of SIN-1, and at a later stage, the effect on the tyrosine nitration and catalytic activity of Vu_FeSOD was examined by in-gel activity and spectrophotometric assays. Both BSA and Vu_FeSOD are nitrated in a dose-dependent manner, and, at least in BSA nitration, the reaction seems to be metal catalyzed.
Open Access
Unlocking nature's drought resilience: a focus on the parsimonious root phenotype and specialised root metabolism in wild Medicago populations
(Springer Nature, 2024-10-28) Calleja Satrustegui, Aitziber; Echeverría Obanos, Andrés; Ariz Arnedo, Idoia; Peralta de Andrés, Francisco Javier; González García, Esther; Ciencias; Zientziak; Institute for Multidisciplinary Research in Applied Biology - IMAB; Unviersidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Background and aims: crop wild relatives, exposed to strong natural selection, exhibit effective tolerance traits against stresses. While an aggressive root proliferation phenotype has long been considered advantageous for a range of stresses, it appears to be counterproductive under drought due to its high metabolic cost. Recently, a parsimonious root phenotype, metabolically more efficient, has been suggested to be better adapted to semiarid environments, although it is not clear that this phenotype is a trait exhibited by crop wild relatives. Methods: firstly, we analysed the root phenotype and carbon metabolism in four Medicago crop wild relatives adapted to a semiarid environment and compared them with the cultivated M. truncatula Jemalong (A17). Secondly, we exposed the cultivated (probably the least adapted genotype to aridity) and the wild (the most common one in arid zones) M. truncatula genotypes to water deficit. The carbon metabolism response in different parts of their roots was analysed. Results: a reduced carbon investment per unit of root length was a common trait in the four wild genotypes, indicative of an evolution towards a parsimonious root phenotype. During the water deficit experiment, the wild M. truncatula showed higher tolerance to drought, along with a superior ability of its taproot to partition sucrose and enhanced capacity of its fibrous roots to maintain sugar homeostasis. Conclusion: a parsimonious root phenotype and the spatial specialization of root carbon metabolism represent two important drought tolerance traits. This work provides relevant findings to understand the response of Medicago species roots to water deficit.
Open Access
Nodule carbohydrate catabolism is enhanced in the Medicago truncatula A17-Sinorhizobium medicae WSM419 symbiosis
(Frontiers Media, 2014) Larrainzar Rodríguez, Estíbaliz; Gil Quintana, Erena; Seminario Huárriz, Amaia; Arrese-Igor Sánchez, César; González García, Esther; Ciencias del Medio Natural; Natura Ingurunearen Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The symbiotic association between Medicago truncatula and Sinorhizobium meliloti is a well-established model system in the legume–Rhizobium community. Despite its wide use, the symbiotic efficiency of this model has been recently questioned and an alternative microsymbiont, S. medicae, has been proposed. However, little is known about the physiological mechanisms behind the higher symbiotic efficiency of S. medicae WSM419. In the present study, we inoculated M. truncatula Jemalong A17 with either S. medicae WSM419 or S. meliloti 2011 and compared plant growth, photosynthesis, N2-fixation rates, and plant nodule carbon and nitrogen metabolic activities in the two systems. M. truncatula plants in symbiosis with S. medicae showed increased biomass and photosynthesis rates per plant. Plants grown in symbiosis with S. medicae WSM419 also showed higher N2-fixation rates, which were correlated with a larger nodule biomass, while nodule number was similar in both systems. In terms of plant nodule metabolism, M. truncatula–S. medicae WSM419 nodules showed increased sucrose-catabolic activity, mostly associated with sucrose synthase, accompanied by a reduced starch content, whereas nitrogen-assimilation activities were comparable to those measured in nodules infected with S. meliloti 2011. Taken together, these results suggest that S. medicae WSM419 is able to enhance plant carbon catabolism in M. truncatula nodules, which allows for the maintaining of high symbiotic N2-fixation rates, better growth and improved general plant performance.
Open Access
Root system of Medicago sativa and Medicago truncatula: drought effects on carbon metabolism
(Springer, 2021-03-18) Echeverría Obanos, Andrés; González García, Esther; Ciencias; Zientziak; Institute for Multidisciplinary Research in Applied Biology - IMAB
Aims: Here, we assess the differential impact of drought on root carbon metabolism in the widely cultivated alfalfa (Medicago sativa, Ms) and the model legume Medicago truncatula (Mt). Understanding how carbon allocation is regulated under drought stress conditions is a central issue to improving alfalfa productivity under future climate change scenarios. Methods: Alfalfa and Medicago truncatula were compared under water deficit conditions. Root carbon metabolism of the taproot and fibrous roots was analysed. M. truncatula drought tolerance variability was compared to that of alfalfa using six accessions of the Medicago Hapmap project. The prominent taproot is much less developed in M. truncatula than in alfalfa with the former exhibiting an extensive fibrous root system. Results: In both examined Medicago species the taproot contained the major pools of soluble protein, sucrose and pinitol, whereas the major pools of hexoses and carbon metabolism enzymes appeared to be in the fibrous roots. Under water-deficit conditions, the response of M. sativa strongly differed from that of M. truncatula at the root level. Conclusions: Water deficit conditions differentially modulate the root carbon metabolism of M. sativa and M. truncatula. Mt maintained a more active carbon metabolism in the fibRs, as sucrose, myo-inositol and pinitol accumulated to cope with the water deficit (WD). Conversely, the root system of Ms did not accumulate cyclitols and carbon metabolism was more severely affected under water deficit conditions. This differentially exerted control may determine the drought response of these two close relatives.
Open Access
Drought stress provokes the down-regulation of methionine and ethylene biosynthesis pathways in Medicago truncatula roots and nodules
(Wiley, 2014) Larrainzar Rodríguez, Estíbaliz; Molenaar, Johanna A.; Wienkoop, Stefanie; Gil Quintana, Erena; Alibert, Bénédicte; Limami, Anis M.; Arrese-Igor Sánchez, César; González García, Esther; Ciencias del Medio Natural; Natura Ingurunearen Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 735/2008
Symbiotic nitrogen fixation is one of the first physiological processes inhibited in legume plants under water-deficit conditions. Despite the progress made in the last decades, the molecular mechanisms behind this regulation are not fully understood yet. Recent proteomic work carried out in the model legume Medicago truncatula provided the first indications of a possible involvement of nodule methionine (Met) biosynthesis and related pathways in response to waterdeficit conditions. To better understand this involvement, the drought-induced changes in expression and content of enzymes involved in the biosynthesis of Met, S-adenosyl-Lmethionine (SAM) and ethylene in M. truncatula root and nodules were analyzed using targeted approaches. Nitrogenfixing plants were subjected to a progressive water deficit and a subsequent recovery period. Besides the physiological characterization of the plants,the content of total sulphur,sulphate and main S-containing metabolites was measured. Results presented here show that S availability is not a limiting factor in the drought-induced decline of nitrogen fixation rates in M. truncatula plants and provide evidences for a downregulation of the Met and ethylene biosynthesis pathways in roots and nodules in response to water-deficit conditions.
Open Access
Long-term mannitol-induced osmotic stress leads to stomatal closure, carbohydrate accumulation and changes in leaf elasticity in Phaselous vulgaris leaves
(Academic Journals, 2010) Sassi, Sameh; Aydi, Samir; Hessini, Kamel; González García, Esther; Arrese-Igor Sánchez, César; Abdelly, Chedly; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
The effect of long-term osmotic stress was investigated in leaves of two common bean lines, with contrasting tolerance: Flamingo (tolerant) and coco blanc (sensitive). Water relations, organic solute, ion accumulation and amino acids content as well as osmotic adjustment (OA) were studied during an extended exposure to osmotic stress. Osmotic stress was applied by means of 50 mM mannitol for 15 days. At the end of the stress period, both osmotic potential at full turgor (psi(100)) and at turgor loss point (psi(0)) decreased significantly in stressed plants compared with the control. The decrease being greater in the sensitive line, showed a greater OA compared with flamingo. Sugars contents increased in stressed plants and seem to be the major components of osmotic adjustment in stressed common bean leaves. The increase was more marked in coco blanc. Osmotic stress tolerance could thus not be associated with higher OA. The possible role of decreased leaf cell elasticity (epsilon(max)) is discussed in relation to osmotic stress tolerance in this species.
Open Access
Potencialidades del frijol caupí para la resiliencia al cambio climático en sistemas agrícolas locales
(2022) Santana-Baños, Yoerlandy; González García, Esther; Ariz Arnedo, Idoia; Carrodeguas Díaz, Sergio; Ciencias; Zientziak
Las evidencias científicas sugieren tres usos fundamentales del frijol caupí, con agro-ecológicas y beneficios productivos, sociales y ambientales en los sistemas agrícolas locales; sin embargo, su rendimiento a nivel mundial y en América no experimenta crecimiento en los últimos años. Los resultados obtenidos en Pinar del Río, Cuba, sugieren la posibilidad de emplearlo como alternativa para la producción de grano pero debe fomentarse, desde la ciencia, la innovación y las instituciones y órganos de decisión a nivel local, la cultura de producción y consumo de esta leguminosa para su aprovechamiento en la sostenibilidad agrícola de los agro-ecosistemas.