Bradyrhizobium japonicum, B. elkanii and B. diazoefficiens Interact with Rice (Oryza sativa), Promote Growth and Increase Yield.

Bradyrhizobium is a genus of plant growth-promoting rhizobacteria (PGPR) that have been studied for several decades mainly for the ability to fix diazotrophic nitrogen after having been established endosymbiotically inside root nodules of the legumes of Fabaceae. The aim of this work was to evaluate the capability of Bradyrhizobium to promote the growth of crops belonging to other families, in this case, rice (Oryza sativa), both in laboratory and in field trials. For laboratory test, surface-sterilized rice seeds were soaked with cultures of each strain and planted in pots. Plant length and dry weight were measured after 35 days. For the field test, rice seeds of varieties Yeruá La Plata and Gurí INTA were inoculated with the three best strains observed in the laboratory test and planted in plots. After 60 days of growth, plant length and dry weight were measured. At harvest time, we measured the dry weight of the aerial part, yield and thousand-grain weight. Inoculation with any of the three species described provoked significant increments compared to the uninoculated control at least in one of the parameters measured, both in the laboratory and in the field tests. Bradyrhizobium japonicum E109 was the strain that promoted rice growth the most in the lab while Bradyrhizobium elkanii SEMIA 587 was the strain that promoted rice growth the most in the field, with increments in yield of approximately 1000 kg/ha. Data obtained suggest that the Bradyrhizobium species promoted all rice growth and yield.

The Mitochondria-Targeted Metabolic Tubular Injury in Diabetic Kidney Disease.

BACKGROUND/AIMS: Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease (ESRD) worldwide, and the importance of tubular injury has been highlighted in recent years. However, the underlying mechanisms and effective therapeutic targets are still unclear. In this study, we investigated mtDNA, mitochondrial dynamics, function and metabolic pathways to determine if mitochondrial damage plays a critical role in the development of tubular injury in DKD patients. METHODS: A cross-sectional study was carried out among healthy controls (HCs, n = 65), diabetes patients without kidney disease (DCs, n = 48) and DKD patients (n = 60). Serum, peripheral blood mononuclear cells (PBMCs) and kidney biopsy specimens were obtained from participants. Metabolomics was employed to investigate cellular metabolism. RESULTS: DKD patients had decreased mtDNA copy numbers and increased mtDNA damage compared to DCs. Mitochondrial fragmentation was specifically presented in tubules, but not in podocytes of DKD patients. The accumulation of damaged mtDNA and fragmented mitochondria resulted in increased reactive oxygen species (ROS) generation, activation of apoptosis and loss of mitochondrial membrane potential (ΔΨm) in tubules and PBMCs. Furthermore, glycolysis and tricarboxylic acid (TCA) cycle was perturbed, and increased dihydroxyacetone phosphate (DHAP) and decreased succinyl-CoA synthetase (SCS) respectively in these two metabolic pathways were identified as potential biomarkers for tubular injury in DKD. CONCLUSION: Our study indicates that mitochondrial damage could be the hallmark of tubular injury in DKD patients, and this would provide a novel and attractive therapeutic target to improve this disease.

The interference of nonylphenol with bacterial cell-to-cell communication.

The interference of nonylphenol (NP) with humans and animals, especially in hormone systems, has been well-studied. There is rarely any record of its effect on bacteria, which dominate in various environments. In our study, we employed Pseudomonas aeruginosa PAO1 as a model microorganism and took its common lifestyle biofilm, mainly regulated by quorum sensing (QS), as a cut-in point to investigate the effect of NP (1, 5, 10 mg L-1) on bacteria. The results showed that more than 5 mg L-1 of NP did interfere with biofilm formation and affected bacterial QS. In detail, the LasI/R circuit, but not the RhlI/R circuit, was considerably obstructed. The decrease in lasI and lasR expression resulted in a significant reduction in N-3-oxo-dodecanoyl homoserine lactone (3OC12-HSL) signals and the downstream production of elastases. Docking results indicated the binding of NP with LasR protein, simulating the binding of 3OC12-HSL with LasR protein, which explained the obstruction of the LasIR circuit. We concluded that NP competed with 3OC12-HSL and blocked 3OC12-HSL binding with the LasR protein, resulting in a direct interference in bacterial biofilm formation. This is the first report of NP interference with bacterial signaling, which is not only helpful to understand the effect of NP on various ecosystems, but is also beneficial to enrich our knowledge of inter-kingdom communication.

Overexpression of the chimeric gene of the floral regulator CONSTANS and the EAR motif repressor causes late flowering in Arabidopsis.

The transcription factor CONSTANS (CO) plays a central role in the photoperiod pathway by integrating the circadian clock and light signals into a control for flowering time. CO induces flowering locus T (FT) and suppressor of overexpression of CO 1 (SOC1) expression, and thereby promotes flowering. The ethylene-responsive element-binding factor associated amphiphilic repression (EAR) motif was used to construct a CONSTANS-EAR motif repressor gene (CO-Rep), which was overexpressed in Arabidopsis under the control of the Cauliflower mosaic virus 35S promoter in order to test its potential for flowering time regulation under inductive long day conditions. Morphological abnormalities in the root and cotyledon formation, and dwarfness were frequently seen in the transgenic plants, suggesting that the proper timing, location, and/or level of CO-Rep expression are important for its application. In morphologically normal CO-Rep plants, both bolting and flowering times under inductive long day conditions were twofold greater than in controls. As a result of the delay in flowering, rosette leaf number at bolting, and rosette and cauline leaf number at flowering increased significantly in CO-Rep plants. RT-PCR analysis demonstrated that FT expression was greatly reduced in the CO-Rep plants, while endogenous CO and SOC1 expression levels were not markedly affected. Conservation of CO among a diverse range of plant species, and its involvement in a variety of photoperiodic responses including flowering, suggests a high potential for use of CO-Rep to manipulate such responses in an agronomically desirable manner.