The Ib subgroup of the bHLH gene family in Arabidopsis contains four members (AtbHLH38, AtbHLH39, AtbHLH100, and AtbHLH101). AtbHLH38 and AtbHLH39 were previously confirmed to interact with FER-like iron deficiency induced transcription factor (FIT), directly functioning in activation of the expression of ferric-chelate reductase FRO2 and high-affinity ferrous iron transporter IRT1. In this work, we characterized the functions of AtbHLH100 and AtbHLH101 in the regulation of the iron-deficiency responses and uptake. Yeast two-hybrid analysis and bimolecular fluorescence complementation assay demonstrated that both AtbHLH100 and AtbHLH101 could interact with FIT. Dual expression of either AtbHLH100 or AtbHLH101 with FIT in yeast cells activated the GUS expression driven by promoters of FRO2 and IRT1. The plants overexpressing FIT together with AtbHLH101 showed constitutive expression of FRO2 and IRT1 in roots, and accumulated more iron in shoots. Further, the single, double, and triple knockout mutants of AtbHLH38, AtbHLH39, AtbHLH100, and AtbHLH101 were generated and characterized. The FRO2 and IRT1 expression in roots and the iron content in shoots were more drastically decreased in the triple knockout mutant of AtbHLH39, AtbHLH100, and AtbHLH101 than that of the other available double and triple mutants of the four genes. Comparison of the physiological responses as well as the expression of FRO2 and IRT1 in the multiple knockout mutants under iron deficiency revealed that AtbHLH100, AtbHLH38, AtbHLH101, and AtbHLH39 played the gradually increased important role in the iron-deficiency responses and uptake. Taken all together, we conclude that the four Ib subgroup bHLH proteins are required and possess redundant functions with differential significance for activation of iron-deficiency responses and uptake in Arabidopsis.

Nine novel Gram-stain-positive bacteria were investigated by a polyphasic taxonomic approach. Based on the analysis of 16S rRNA gene sequences, these strains belonged to the Bacillus cereus group, sharing over 97 % similarity with the known species of this group, and less than 95 % similarity with other species of the genus Bacillus. Multilocus sequence typing analysis showed that they formed nine robust and well-separated branches from the known species. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between the nine strains were, respectively, below the 70 and 96 % threshold values for species definition, and between each strain and the known type strains of this group were also below the two threshold values. On the basis of the phenotypic and phylogenetic data, along with low dDDH and ANI values among these strains, these bacteria are assigned to the following nine novel species of the B. cereus group: Bacillus paranthracis sp. nov., type strain Mn5T (=MCCC 1A00395T=KCTC 33714T=LMG 28873T); Bacillus pacificus sp. nov., type strain EB422T (=MCCC 1A06182T=KCTC 33858T); Bacillus tropicus sp. nov., type strain N24T (=MCCC 1A01406T=KCTC 33711T=LMG 28874T); Bacillus albus sp. nov., type strain N35-10-2T (=MCCC 1A02146T=KCTC 33710T=LMG 28875T); Bacillus mobilis sp. nov., type strain 0711P9-1T (=MCCC 1A05942T=KCTC 33717T=LMG 28877T); Bacillus luti sp. nov., type strain TD41T (=MCCC 1A00359T=KCTC 33716T=LMG 28872T); Bacillus proteolyticus sp. nov., type strain TD42T (=MCCC 1A00365T=KCTC 33715T=LMG 28870T); Bacillus nitratireducens sp. nov., type strain 4049T (=MCCC 1A00732T=KCTC 33713T=LMG 28871T); and Bacillus paramycoides sp. nov., type strain NH24A2T (=MCCC 1A04098T=KCTC 33709T=LMG 28876T).

Cadmium (Cd) is toxic to plant cells. Under Cd exposure, the plant displayed leaf chlorosis, which is a typical symptom of iron (Fe) deficiency. Interactions of Cd with Fe have been reported. However, the molecular mechanisms of Cd-Fe interactions are not well understood. Here, we showed that FER-like Deficiency Induced Transcripition Factor (FIT), AtbHLH38, and AtbHLH39, three basic helix-loop-helix transcription factors involved in Fe homeostasis in plants, also play important roles in Cd tolerance. The gene expression analysis showed that the expression of FIT, AtbHLH38, and AtbHLH39 was up-regulated in the roots of plants treated with Cd. The plants overexpressing AtbHLH39 and double-overexpressing FIT/AtbHLH38 and FIT/AtbHLH39 exhibited more tolerance to Cd exposure than wild type, whereas no Cd tolerance was observed in plants overexpressing either AtbHLH38 or FIT. Further analysis revealed that co-overexpression of FIT with AtbHLH38 or AtbHLH39 constitutively activated the expression of Heavy Metal Associated3 (HMA3), Metal Tolerance Protein3 (MTP3), Iron Regulated Transporter2 (IRT2), and Iron Regulated Gene2 (IREG2), which are involved in the heavy metal detoxification in Arabidopsis (Arabidopis thaliana). Moreover, co-overexpression of FIT with AtbHLH38 or AtbHLH39 also enhanced the expression of NICOTIANAMINE SYNTHETASE1 (NAS1) and NAS2, resulting in the accumulation of nicotiananamine, a crucial chelator for Fe transportation and homeostasis. Finally, we showed that maintaining high Fe content in shoots under Cd exposure could alleviate the Cd toxicity. Our results provide new insight to understand the molecular mechanisms of Cd tolerance in plants.

A six-lobed membrane spanning cellulose synthesis complex (CSC) containing multiple cellulose synthase (CESA) glycosyltransferases mediates cellulose microfibril formation. The number of CESAs in the CSC has been debated for decades in light of changing estimates of the diameter of the smallest microfibril formed from the β-1,4 glucan chains synthesized by one CSC. We obtained more direct evidence through generating improved transmission electron microscopy (TEM) images and image averages of the rosette-type CSC, revealing the frequent triangularity and average cross-sectional area in the plasma membrane of its individual lobes. Trimeric oligomers of two alternative CESA computational models corresponded well with individual lobe geometry. A six-fold assembly of the trimeric computational oligomer had the lowest potential energy per monomer and was consistent with rosette CSC morphology. Negative stain TEM and image averaging showed the triangularity of a recombinant CESA cytosolic domain, consistent with previous modeling of its trimeric nature from small angle scattering (SAXS) data. Six trimeric SAXS models nearly filled the space below an average FF-TEM image of the rosette CSC. In summary, the multifaceted data support a rosette CSC with 18 CESAs that mediates the synthesis of a fundamental microfibril composed of 18 glucan chains.

Biogenic synthesis of silver (AgNPs) and gold nanoparticles (AuNPs) using aqueous extract of Euphrasia officinalis has been reported. Stable AgNPs and AuNPs were formed on adding aqueous solutions of silver nitrate and chloroauric acid with E. officinalis leaf extract, in 19 min and 2 min, respectively. The synthesis method used in present study was simple, reliable, rapid, cost effective and ecofriendly. The synthesized nanoparticles were characterized with field emission transmission electron microscopy (FE-TEM), elemental mapping, selected area diffraction pattern (SAED), energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), particle size distribution, zeta potential and Fourier-transform infrared spectroscopy (FTIR). The UV-Vis spectrum confirmed the synthesis of nanoparticles as the absorption band was observed at 450 nm for AgNPs and at 558 nm for AuNPs. The TEM images revealed quasi-spherical shape of AgNPs and AuNPs. The size of nanoparticles was determined to be 40.37 ± 1.8 nm for AgNPs and 49.72 ± 1.2 nm for AuNPs. The zeta potential value demonstrated the negative surface charge and stable nature of nanoparticles. Crystalline nature of the nanoparticles in the face-centred cubic (fcc) structure was confirmed by the peaks in the XRD pattern and SAED pattern. FTIR results showed the functional groups involved in reduction of silver and gold ions to metal nanoparticles. For biomedical application, the nanoparticles have been explored for anticancer, antibacterial and biofilm inhibition activities. It was observed that AgNPs exert anticancer activity against human lung cancer (A549) and human cervical cancer (HeLa) cell lines. On the other hand, AuNPs were able to inhibit only human cervical cancer cells. Furthermore, the AgNPs were active against clinically isolated human pathogens like Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Vibrio parahaemolyticus. Additionally, AgNPs also showed biofilm inhibition activity against S. aureus and P. aeruginosa.

Silver nanoparticles (AgNPs) are known to have bacteriostatic and bactericidal effects. The present study highlights the extracellular synthesis of AgNPs and its antibacterial properties. The AgNPs were synthesized using Pseudomonas sp. THG-LS1.4 strain which had been isolated from soil. The AgNPs were characterized by field emission-transmission electron microscopy (FE-TEM), X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, and particle size distribution (DLS). The AgNPs displayed maximum absorbance at 412 nm and were irregular in shape ranging from 10 to 40 nm. The XRD spectroscopy results demonstrated the crystalline nature of nanoparticles. The AgNPs showed antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Candida tropicalis, Vibrio parahaemolyticus, Escherichia coli and Pseudomonas aeruginosa. Furthermore, the AgNPs were also evaluated for their increased antibacterial activities with various antibiotics against Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica. Additionally, AgNPs showd biofilm inhibition activity. The biosynthesized AgNPs were found to be a potent agent against tested pathogens. More importantly, we highlight the applications of AgNPs as an antimicrobial agent.

This study highlights the facile, reliable, cost effective, and ecofriendly synthesis of silver nanoparticles (AgNPs) using Borago officinalis leaves extract efficiently. The biosynthesis of AgNPs was verified by UV-Vis spectrum which showed the surface plasmon resonance (SPR) band at 422 nm. Transmission electron microscope (TEM) analysis revealed that the particles were spherical, hexagonal, and irregular in shape and had size ranging from 30 to 80 nm. The energy dispersive X-ray spectroscopy (EDX) and elemental mapping have displayed the purity and maximum distribution of silver in the AgNPs. The crystalline nature of AgNPs had been identified using X-ray diffraction (XRD) and selected area diffraction pattern (SAED). The particle size analysis revealed that the Z-average diameter of the AgNPs was 50.86 nm with polydispersity index (PDI) 0.136. Zeta potential analysis displayed the colloidal stability of AgNPs. This work also showed the efficacy of AgNPs against lung cancer cell lines (A549) and cervical cancer cell line (HeLa), in vitro. The AgNPs showed cytotoxicity to the A549 and HeLa cancer cell line at the concentrations 5 and 2 μg/ml. The AgNPs were also explored for the antibacterial activity including biofilm inhibition against pathogenic bacteria. The B. officinalis leaves extract can be used efficiently for green synthesis AgNPs. The biosynthesized AgNPs demonstrated potentials as anticancer and antibacterial agents. This work provides helpful insight into the development of new anticancer and antimicrobial agents.

Physical and functional interactions between pectin and cellulose are required for normal wall assembly and plant growth, as revealed in analyses of mutants for a pectin methyltransferase.