New insights into azelaic acid-induced resistance against Alternaria Solani in tomato plants.

BACKGROUND: The effect of azelaic acid (Aza) on the response of tomato plants to Alternaria solani was investigated in this study. After being treated with Aza, tomato plants were infected with A. solani, and their antioxidant, biochemical, and molecular responses were analyzed. RESULTS: The results demonstrated that H2O2 and MDA accumulation increased in control plants after pathogen infection. Aza-treated plants exhibited a remarkable rise in peroxidase (POD) and catalase (CAT) activities during the initial stages of A. solani infection. Gene expression analysis revealed that both Aza treatment and pathogen infection altered the expression patterns of the SlNPR1, SlERF2, SlPR1, and SlPDF1.2 genes. The expression of SlPDF1.2, a marker gene for the jasmonic acid/ethylene (JA/ET) signaling pathway, showed a remarkable increase of 4.2-fold upon pathogen infection. In contrast, for the SlNPR1, a key gene in salicylic acid (SA) pathway, this increased expression was recorded with a delay at 96 hpi. Also, the phytohormone analysis showed significantly increased SA accumulation in plant tissues with disease development. It was also revealed that tissue accumulation of JA in Aza-treated plants was increased following pathogen infection, while it was not increased in plants without pathogen inoculation. CONCLUSION: The results suggest that the resistance induced by Aza is mainly a result of modulations in both SA and JA pathways following complex antioxidant and molecular defense responses in tomato plants during A. solani infection. These findings provide novel information regarding inducing mechanisms of azelaic acid which would add to the current body of knowledge of SAR induction in plants as result of Aza application.

Antibacterial effect of cerium oxide nanoparticle against Pseudomonas aeruginosa.

BACKGROUND: Antibiotics have been widely used for the treatment of bacterial infections for decades. However, the rapid emergence of antibiotic-resistant bacteria has created many problems with a heavy burden for the medical community. Therefore, the use of nanoparticles as an alternative for antibacterial activity has been explored. In this context, metal nanoparticles have demonstrated broad-spectrum antimicrobial activity. This study investigated the antimicrobial activity of naked cerium oxide nanoparticles dispersed in aqueous solution (CNPs) and surface-stabilized using Pseudomonas aeruginosa as a bacterial model. METHODS: Gelatin-polycaprolactone nanofibers containing CNPs (Scaffold@CNPs) were synthesized, and their effect on P. aeruginosa was investigated. The minimum inhibitory and bactericidal concentrations of the nanoparticls were determined in an ATCC reference strain and a clinical isolate strain. To determine whether the exposure to the nanocomposites might change the expression of antibiotic resistance, the expression of the genes shv, kpc, and imp was also investigated. Moreover, the cytotoxicity of the CNPs was assessed on fibroblast using flow cytometry. RESULTS: Minimum bactericidal concentrations for the ATCC and the clinical isolate of 50 µg/mL and 200 µg/mL were measured, respectively, when the CNPs were used. In the case of the Scaffold@CNPs, the bactericidal effect was 50 µg/mL and 100 µg/mL for the ATCC and clinical isolate, respectively. Interestingly, the exposure to the Scaffold@CNPs significantly decreased the expression of the genes shv, kpc, and imp. CONCLUSIONS: A concentration of CNPs and scaffold@CNPs higher than 50 µg/mL can be used to inhibit the growth of P. aeruginosa. The fact that the scaffold@CNPs significantly reduced the expression of resistance genes, it has the potential to be used for medical applications such as wound dressings.

Recombinant pebulin protein, a type 2 ribosome-inactivating protein isolated from dwarf elder (Sambucus ebulus L.) shows anticancer and antifungal activities in vitro.

In this study, encoding sequence of a new type 2 RIP (pebulin) was isolated and cloned from dwarf elder (Sambucus ebulus L.) native to the northern regions of Iran. The nucleotide sequence of pebulin was ligated to the pET-28a(+) expression plasmid and cloned into the E. coli strain BL21 (DE3) in order to express heterologously of recombinant protein. The recombinant pebulin protein was mainly produced in the form of insoluble inclusion bodies probably because to absence of N-glycosylation process in E. coli. Therefore, in order to increase the expression of recombinant protein in soluble form, co-expression of the target protein with the pG-Tf2 chaperone plasmid and incubation of bacterial culture under low temperature were used to enhance solubility and accumulation of recombinant protein. After purification of the recombinant protein using affinity chromatography method, the bioactivity of pebulin was analyzed by hemagglutination, anticancer, and antifungal assays. The results of the hemagglutination assay showed that purified pebulin agglutinated erythrocytes in all human blood groups. In addition, pebulin considerably inhibited the proliferation of cancer cell lines MCF-7 and HT-29 in a time- and dose-dependent manner and indicated remarkably growth-inhibiting effect against the plant pathogenic fungi such as Alternaria solani and Fusarium oxysporum.

Molecular cloning and in-depth bioinformatics analysis of type II ribosome-inactivating protein isolated from Sambucus ebulus.

Plant ribosome-inactivating proteins (RIPs) are N-glycosidases which inhibit protein synthesis through depurination of the ribosomal RNA sequence. Type II RIPs are heterodimer proteins which can bind to cell surfaces. The cytotoxicity of these RIPs is different. Sambucus spp. are a rich source of RIP proteins with different properties. In the present study, a type II RIP was isolated from S. ebulus plant that grows widely in the north of Iran, and different bioinformatics tools were used for the evaluation of physicochemical, functional and 3D protein characteristics. The results showed significant differences among isolated RIP and other Sambucus RIP proteins. The study of these differences can not only expand our insight into the functioning mechanisms of plant RIPs but also provide information about a novel RIP protein with potential biological applications.

De novo RNA sequencing analysis of Aeluropus littoralis halophyte plant under salinity stress.

The study of salt tolerance mechanisms in halophyte plants can provide valuable information for crop breeding and plant engineering programs. The aim of the present study was to investigate whole transcriptome analysis of Aeluropus littoralis in response to salinity stress (200 and 400 mM NaCl) by de novo RNA-sequencing. To assemble the transcriptome, Trinity v2.4.0 and Bridger tools, were comparatively used with two k-mer sizes (25 and 32 bp). The de novo assembled transcriptome by Bridger (k-mer 32) was chosen as final assembly for subsequent analysis. In general, 103290 transcripts were obtained. The differential expression analysis (log2FC > 1 and FDR < 0.01) showed that 1861 transcripts expressed differentially, including169 up and 316 down-regulated transcripts in 200 mM NaCl treatment and 1035 up and 430 down-regulated transcripts in 400 mM NaCl treatment compared to control. In addition, 89 transcripts were common in both treatments. The most important over-represented terms in the GO analysis of differentially expressed genes (FDR < 0.05) were chitin response, response to abscisic acid, and regulation of jasmonic acid mediated signaling pathway under 400 mM NaCl treatment and cell cycle, cell division, and mitotic cell cycle process under 200 mM treatment. In addition, the phosphatidylcholine biosynthetic process term was common in both salt treatments. Interestingly, under 400 mM salt treatment, the PRC1 complex that contributes to chromatin remodeling was also enriched along with vacuole as a general salinity stress responsive cell component. Among enriched pathways, the MAPK signaling pathway (ko04016) and phytohormone signal transduction (ko04075) were significantly enriched in 400 mM NaCl treatment, whereas DNA replication (ko03032) was the only pathway that significantly enriched in 200 mM NaCl treatment. Finally, our findings indicate the salt-concentration depended responses of A. littoralis, which well-known salinity stress-related pathways are induced in 400 mM NaCl, while less considered pathways, e.g. cell cycle and DNA replication, are highlighted under 200 mM NaCl treatment.

Establishment of hairy root cultures by Agrobacterium rhizogenes mediated transformation of Trachyspermum ammi L. for the efficient production of thymol.

Trachyspermum ammi is an important medicinal plant that contains a bioactive compound namely thymol. In the study, T. ammi was transformed by Agrobacterium rhizogenes strains. Seedling stem explants were inoculated with A. rhizogenes strains A4, LBA 9402, ATCC 15834, and the effect of different co-cultivation media along with incorporation of acetosyringone (100 µM) was evaluated comparatively on the frequency of hairy root induction. The polymerase chain reaction using rolB and virD specific primers was served to confirm the putative transformed hairy roots. All strains established hairy root with various frequencies, among which strain ATCC 15834 was significantly the most efficient strain for hairy root induction (84.3%). Half-strength B5 medium and incorporation of acetosiryngone (100 µM) were also significantly optimal for hairy root induction. Hairy roots culture induced by ATCC 15834 using half-strength B5 liquid medium supplemented with 30 g L-1 sucrose indicated the highest accumulation of biomass (99.05 g L-1 FW and 10.95 g L-1 DW) and thymol content (11.30 mg g-1 DM) at 20 days. Nearly 4.9-fold and 5.3-fold increment of biomass and thymol accumulation was observed, respectively, at 20 days in comparison with the untransformed control roots. The results showed the high potential of T. ammi hairy roots for the biosynthesis of thymol.