Test of Host Sanction Hypothesis in Soybean Plants Co-inoculated with Nitrogen Fixing and Non-fixing Bradyrhizobium japonicum

Aims: We tested the proposed mechanism for potential sanctions, that the plant would reduce viability of non-fixing rhizobia inside nodules, performing viable Bradyrhizobium japonicum counts from co-occupied and single-occupied nodules in co-inoculated soybean plants. Study Design: Plants were co-inoculated with two strains of B. japonicum, a highly efficient nitrogen fixing wild-type strain BJD321, and the non-fixing, nifH mutant derivative A3, to produce co-occupied nodules as well as single-occupied nodules. Strain A3 lacks nitrogenase activity but shows similar infection and nodule formation levels respect to the wild-type. As the strains used are equivalent in competitive and nodulation abilities and only differ in the nitrogen fixation ability (by nitrogenase inactivation), and share the same plant, root and even nodule, we can assert that themechanism being tested is plant host sanction, and no other proposed mechanisms like partner choice. Place and Duration of Study: Nitrogen Metabolism Lab, Department of Soil Microbiology and Symbiotic Systems at Zaidín Experimental Station (CSIC State Agency, Granada, Spain). 2010- 2011. Methodology: Axenic seedlings of soybean (Glycine max) cultivar Williams were inoculated with 2 ml of bacterial suspension of BJD321 or A3 strains, alone or in 1:1 mixture and supplied with sterilized N free nutrient solution. Four weeks after inoculation plants of each inoculation treatment (BJD321 + A3, BJD321 only, A3 only) were harvested, nodules were counted and weighed and plated to determine rhizobial strain occupation and population. In the aerial part of plants, determinations of weight, N and C content were done. Results: Co-inoculated plants and plants only inoculated with the BJD321 strain showed a similar nitrogen fixation since they did not differ in dry weight, total N content and total C content. Plants with different inoculation treatments (BJD321 + A3, BJD321 only and A3 only) did not differ in nodule number. In co-inoculated plants, nodule occupation did not differ from the expected among strains (about 33% BJD321 + A3, BJD321 only and A3 only), and the weight of nodules occupied by both strains, BJD321 or A3 alone did not differ. In co-inoculated plants rhizobial viability did not differ between BJD321 and A3 strains, either comparing co-occupied nodules or single-occupied nodules. Nodule size and CFU of rhizobia inside nodules were not correlated, either in coinoculated plants or plants inoculated with BJD321 strain alone. Conclusion: We can conclude that in the soybean-B. japonicum system, plants facing the presence of fixing and non-fixing rhizobial strains do not sanction cheating and can perform as well as plants inoculated with the fixing strain alone.Fil: Marco, Diana Elizabeth. Universidad Nacional de Córdoba. Facultad de Cs.agropecuarias. Area de Producción Organica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Talbi, Chouhra. Universidad Nacional Autónoma de México; MéxicoFil: Bedmar, Eulogio. Consejo Superior de Investigaciones Científicas. Estación Experimental del Zaidín; Españ

Genetic diversity and breed-informative SNPs identification in domestic pig populations using coding SNPs

Background: The use of breed-informative genetic markers, specifically coding Single Nucleotide Polymorphisms (SNPs), is crucial for breed traceability, authentication of meat and dairy products, and the preservation and improvement of pig breeds. By identifying breed informative markers, we aimed to gain insights into the genetic mechanisms that influence production traits, enabling informed decisions in animal management and promoting sustainable pig production to meet the growing demand for animal products.Methods: Our dataset consists of 300 coding SNPs genotyped from three Italian commercial pig populations: Landrace, Yorkshire, and Duroc. Firstly, we analyzed the genetic diversity among the populations. Then, we applied a discriminant analysis of principal components to identify the most informative SNPs for discriminating between these populations. Lastly, we conducted a functional enrichment analysis to identify the most enriched pathways related to the genetic variation observed in the pig populations.Results: The alpha diversity indexes revealed a high genetic diversity within the three breeds. The higher proportion of observed heterozygosity than expected revealed an excess of heterozygotes in the populations that was supported by negative values of the fixation index (FIS) and deviations from the Hardy-Weinberg equilibrium. The Euclidean distance, the pairwise FST, and the pairwise Nei’s GST genetic distances revealed that Yorkshire and Landrace breeds are genetically the closest, with distance values of 2.242, 0.029, and 0.033, respectively. Conversely, Landrace and Duroc breeds showed the highest genetic divergence, with distance values of 2.815, 0.048, and 0.052, respectively. We identified 28 significant SNPs that are related to phenotypic traits and these SNPs were able to differentiate between the pig breeds with high accuracy. The Functional Enrichment Analysis of the informative SNPs highlighted biological functions related to DNA packaging, chromatin integrity, and the preparation of DNA into higher-order structures.Conclusion: Our study sheds light on the genetic underpinnings of phenotypic variation among three Italian pig breeds, offering potential insights into the mechanisms driving breed differentiation. By prioritizing breed-specific coding SNPs, our approach enables a more focused analysis of specific genomic regions relevant to the research question compared to analyzing the entire genome

Medicago sativa L.: mejora y nuevos aspectos de su valor nutritivo y funcional por co-inoculación bacteriana

Objective: to study the effect of co-inoculation with Ensifer meliloti and Halomonas maura of the leguminous Medicago sativa L., on growth, nutritional and functional value, grown under salinity conditions. Methods: plants of M. sativa were grown in a solution with a mixture of salts (CaSO4, MgCl, NaCl and NaHCO 3) and were co-inoculated with its specific rhizobium and the halophilic moderated bacterium H. maura. Different physiologic parameters were determined, as well as, nitrogen and minerals content. Furthermore, an assay of in vitro digestibility was carried out. Results: salinity had a negative effect on the plants; however, co-inoculation increased yield, nitrogen content, total minerals, Ca and Mg. Moreover, physiologic parameters as water potential and leghemoglobin content in fresh nodules were higher compared to those of plants inoculated only with E. meliloti. Both, salinity and bacterial treatment with E. meliloti and H. maura increased the antioxidant capacity of the legume, in dialyzates and retentates collected after an in vitro digestibility assay. Conclusion: co-inoculation of plants with E. meliloti and H. maura could improve the alfalfa yield under specific salinity conditions, increasing the nutritional and functional value of the plants. M. sativa could be considered in the formulations of nutritional supplements for the human diet.Este trabajo forma parte de la Tesis Doctoral de Rosario Martínez y ha sido financiado por European Regional Development Fund (ERDF) y cofinanciado por los proyectos P07-AGR-2704 y RNM-4746 de la Junta de Andalucía (España). Queremos agradecer a los grupos AGR-145 y BIO-275 así como al Profesor José Aguilar su ayuda

Nuevas estrategias para mejorar la fijación simbiótica de nitrógeno en Phaseolus vulgaris cultivada en suelos afectados por estreses abióticos

Tesis Univ. Granada. Departamento de Biología Vegetal. Leída el 16 de diciembre de 201

Characterization of the Symbiotic Nitrogen-Fixing Common Bean Low Phytic Acid (lpa1) Mutant Response to Water Stress

The common bean (Phaseolus vulgaris L.) low phytic acid (lpa1) biofortified genotype produces seeds with improved nutritional characteristics and does not display negative pleiotropic effects. Here we demonstrated that lpa1 plants establish an efficient nitrogen-fixing symbiosis with Rhizobium etli CE3. The lpa1 nodules showed a higher expression of nodule-function related genes than the nodules of the parental wild type genotype (BAT 93). We analyzed the response to water stress of lpa1 vs. BAT 93 plants grown under fertilized or under symbiotic N2-fixation conditions. Water stress was induced by water withholding (up to 14% soil moisture) to fertilized or R. etli nodulated plants previously grown with normal irrigation. The fertilized lpa1 plants showed milder water stress symptoms during the water deployment period and after the rehydration recovery period when lpa1 plants showed less biomass reduction. The symbiotic water-stressed lpa1 plants showed decreased nitrogenase activity that coincides with decreased sucrose synthase gene expression in nodules; lower turgor weight to dry weight (DW) ratio, which has been associated with higher drought resistance index; downregulation of carbon/nitrogen (C/N)-related and upregulation of stress-related genes. Higher expression of stress-related genes was also observed in bacteroids of stressed lpa1 plants that also displayed very high expression of the symbiotic cbb3 oxidase (fixNd)

Foliar application with salicylic acid alleviates cadmium toxicity in chia (Salvia hispanica L.)

Cadmium (Cd) accumulation is one of the serious global issues among the multitude of food security challenges. Their toxic effects are evident in different physiological and metabolic behaviors of plants. In this context, a potted study was conducted to investigate the effectiveness of salicylic acid (SA) spraying in alleviating Cd toxicity in chia (Salvia hispanica) seedlings. This pseudocereal as a superfood is characterized by high nutritional value and high therapeutic potential. We examined some growth traits, photosynthetic pigments, anthocyanin, antioxidant defense system, malondialdehyde (MDA), and certain osmoregulatory molecules. The results showed that the chia seedlings exposed to Cd showed a substantial decline in growth, especially in shoot and root length and number of leaves (25.5, 21.5, and 22.6%, respectively), whereas the aforesaid biochemical parameters were not significantly affected. However, SA treatment alleviated the Cd stress applied and markedly enhanced the stem and root growth, especially shoot length of about 32.3% compared to Cd treatment. Under combined treatment Cd+SA, we also recorded a significant increase in the accumulation of proline (85.3%) and anthocyanin (83.1%), and a significant enhancement in peroxidase activity (34.9%), compared to control. These responses exhibit the involvement of SA in mitigating Cd-induced oxidative damage and improving Cd tolerance in Chia. Principal component analysis and cluster analysis showed differences between individual and combined treatment. Based on these results, exogenous SA used in the right amounts could alleviate Cd-induced stress and boost chia seedlings’ growth