Alireza Iranbakhsh

Nickel (Ni) toxicity, characterized by an excessive accumulation of this detrimental element in plants, can significantly hinder growth and reduce crop yields (Ghasemi et al. 2009). As one of the 2...

Ultraviolet (UV) radiation is a significant environmental stressor for plant growth, stress responses and secondary metabolites. UV-B (280–315 nm) and UV-C (100–280 nm) wavelengths are particularly known to induce oxidative stress among the UV wavelenghts. The physiological and biochemical reactions of Portulaca oleracea with differing intensity of UV radiation are still uncertain. P. oleracea plants were exposed to UV-B and UV-C with measurements at 0, 200, 400 and 600 J.m⁻². Both UV-B and UV-C treatments reduced plant height, biomass, and leaf water potentially the largest reductions were under UV-C treatments in fact at 600 J.m⁻². Photosynthetic pigments such as chlorophyll a, chlorophyll b and carotenoids decreased with rising intensities of ultraviolet (UV). However, proline, malondialdehyde (MDA), phenols and flavonoids increased indicating more oxidative stress. Activities of the antioxidant enzymes catalase and peroxidase increased under increasing UV-C doses; the antioxidants increased with intense UV-C. Although UV-B and UV-C radiation produces physiological and biochemical effects that are dose-dependent in the greenhouse weed, P. oleracea, the exposure of plants to UV-C caused growth inhibition and decrease in pigments, but induced the defense mechanism against oxidative stress. Overall findings shed light on plant resilience to natural stress together mitigation measures for sustainable agro-ecosystem management amidst an increasing UV environment.

RNA sequencing (RNA-Seq) is a powerful tool for exploring transcriptional responses to environmental cues and elucidating gene regulatory networks. This study investigates how arbuscular mycorrhizal fungi (AMF) alleviate water deficit (WD) stress in Triticum aestivum seedlings through transcriptomic analysis. A comparative transcriptome analysis was performed on wheat roots under two irrigation regimes, well-watered (WW) and WD, and/or AMF inoculation, to identify differentially expressed genes (DEGs). AMF inoculation modulated the expression of genes involved in osmotic adjustment and protective metabolite biosynthesis. While genes such as P5CS, ARG, OAT, and TaPROT2 were downregulated in AMF-treated plants under WD, asparagine synthase (ASNS) was notably upregulated. Furthermore, AMF symbiosis enhanced the expression of genes related to polyamine and GABA metabolism under WD stress. A significant upregulation of antioxidant-related genes, particularly GSTU1, indicated an AMF-induced strengthening of the antioxidant defense system. Additionally, AMF treatment upregulated multiple nutrient transporter genes, including PHT, AMT, NPF, NRT, HAK/AKT, aquaporins, sugar transporters, and ABC transporters, thereby contributing to improved nutritional status. AMF also influenced carbohydrate metabolism to promote cell wall (CW) biosynthesis and remodelling, highlighting its role in structural adaptation to drought. These findings offer key molecular insights into the mechanisms by which AMF symbiosis modulates gene expression to improve wheat drought tolerance under varying irrigation conditions.

Epigenetic responses of in vitro-cultured plants to elicitation with salicylic acid (SA) and methyl jasmonate (MJ) have been little explored. This study addresses how pepper seedlings respond to incorporating SA (0 and 10 µM) and/or MJ (0 and 10 µM) into the culture medium at physiological and molecular levels. The individual application of MJ or SA enhanced root fresh weight by an average of 59.8%. However, the mixed treatment synergistically augmented the root biomass by 2.2-fold. SA was individually more effective than MJ in triggering changes in the DNA methylome profiles. The epigenetic cytosine methylation in the MJ + SA group differed from that of the individual treatments. The individual SA treatment led to severe DNA hypermethylation, which was modified with the MJ application. Moreover, MJ and/or SA-mediated upregulation of the histone deacetylase (HDA) gene also confirmed the epigenetic regulation at the histone modification level. The MJ elicitor showed greater effectiveness in influencing the transcription of the target genes than the SA one. The expression of the MAPK kinase and ethylene-responsive transcription factor (EREB) genes displayed a similar upward trend. Applying pepper seedlings with MJ and SA increased proline concentrations and catalase activities. The simultaneous application of MJ and SA supplements effectively stimulated secondary metabolism, indicated by increased soluble phenols and activity of the phenylalanine ammonia-lyase enzyme. This study presents novel comparative insights into the SA and MJ-mediated epigenetic modifications. These findings can be employed to design in vitro culture systems and implement large-scale projects.

To investigate selenium effects on anatomic features of Thymus daenensis, three concentrations of bulk and nanoparticles of the element (2, 4 and 8 ppm) along with distilled water, as a control, were sprayed on foliar of young seedlings of the plant species for six times with 2 weeks intervals. Transverse sections of stems, roots and leaves of the treated plants were manually produced and stained by Carmine and Methylene blue. Average of 5 readings was recorded for each treatment on several anatomic traits. Statistical analysis of the data revealed that the effects of selenium treatments were significantly different, at 1% of probability, on all of the studied anatomic characters. The first level of nanoparticles showed the most positive effects on several root characteristics. The highest level of selenium nanoparticles (8 ppm) showed the most positive effects on stem diameter and stem vascular cylinder diameter. The last two levels of nanoparticles had similar and the largest effect on stem epidermis thickness. The lowest level of bulk selenium (2 ppm) showed the most increment on leaf characteristics. Application of a low concentration of selenium by foliar spraying on young plants of the species is suggested for more vegetative growth and higher photosynthetic efficiency

Background: Lactic acid bacteria (LAB) are among the most common probiotics and play a significant role in promoting health within the human intestinal microbiota. Their protective functions in the intestine include producing antimicrobial compounds, regulating the balance of the intestinal microbiome, and more. Objectives: This study aims to investigate the antimicrobial effects of bacteriocin extracted from Lactobacillus plantarum (L. plantarum) on Escherichia coli (E. coli) strains that cause treatment-resistant urinary tract infections (UTIs) in humans and mastitis in livestock. Methods: Twenty E. coli isolates were obtained from patients with UTIs and cows with mastitis. After culturing the samples on Eosin-methylene blue, McConkey agar, and blood agar, the strains were identified using biochemical tests. Bacteriocin produced by L. plantarum ATCC8014 was extracted, and its concentration was measured using the Bradford method. The antimicrobial effect of the bacteriocin was assessed using the broth microdilution method to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Additionally, the bacteriocin's antimicrobial activity was evaluated through three repetitions of disk diffusion and agar well diffusion methods. Results: The findings revealed that the MIC and MBC concentrations for all human and animal strains were 13.38 μg/mL and 26.76 μg/mL, respectively. Notably, two animal samples (No. 3 and No. 10) and one human sample (No. 6) showed lower MIC and MBC concentrations compared to the other samples and the standard E. coli sample. However, all strains were resistant to bacteriocin in the disk diffusion and agar well diffusion methods. Conclusions: The data indicate a high risk of increasing treatment-resistant E. coli strains in UTIs and livestock, which could pose a significant threat to public and animal health. Therefore, it is essential to further investigate the effects of different bacteriocins on these resistant strains, in conjunction with antibiotic therapies.