In this study, the effects of different concentrations of silica nanoparticles (NPs) were studied on growth, membrane stability, and antioxidant properties of Matricaria chamomilla in vitro. The sterilized seeds were incubated in different concentrations of silica NPs (0, 2, 4, 6 g L-1) for one hour and then were cultured on Murashing and Skoog medium. Silica NPs application enhanced relative water content and fresh and dry weight of leaf and root. The highest growth was observed at 4 g L-1silica NPs. Hydrogen peroxide and malondialdehyde significantly reduced at 4 g L-1silica NPs. Total phenol and flavonoid contents increased by silica NPs treatment, and induction effect of silica NPs was more prominent at 6 g L-1silica NPs. Low level of IC50 was detected at 6 g L-1silica NPs. Overall, application of silica NPs at proper concentration can improve growth and induces the production of metabolites in M. chamomilla. Manuscript profile

Cyanobacteria are an important source of natural products. In this article, we briefly review the responses of cyanobacteria to different stresses. Abiotic stresses (temperature, salt, heavy metals, metalloid and ultraviolet (UV) influence cell growth and metabolism in cyanobacteria. Salt stress is a major abiotic factor that decreases the growth of cyanobacteria and affects the different processes including photosynthesis, respiration, and metabolism. The basic mechanisms for salinity adaptation include the active extrusion of inorganic ions and the accumulation of compatible solutes such as sucrose, trehalose, glucosyl glycerol, and glycine betaine. Cyanobacteria have a complex antioxidative system including enzymatic and nonenzymatic antioxidants for mitigation of oxidative damage under salt stress. Cyanobacteria have some defense mechanisms for the decline of the direct and indirect destructive effects of UV. These mechanisms include avoidance, scavenging of reactive oxygen species (ROS), synthesis of UV-absorbing/screening compounds such as mycosporine-like amino acids and scytonemin, repair of UV-induced damage in DNA, and resynthesis of proteins. Metals are involved in key metabolic pathways as redox cofactors in proteins. High concentration of metals causes the generation of ROS and oxidative damage. Thus, the major role of metal homeostasis in maintaining the intracellular concentration of metal within a range compatible with cell viability becomes evident. The biosynthesis of metabolites can be triggered by a number of abiotic stresses because they affect metabolic pathways. Manuscript profile

This work evaluated the effect of drought stress on seedling growth, protein, soluble sugars, and phenolic compounds of two cultivars of canola (RGS003 and Sarigol). Drought stress was induced with polyethylene glycol (PEG) at 0, 5, 10, and 15%. Drought stress increased root fresh weight in both cultivars and the effect of drought was more pronounced in RGS003. Shoot fresh weight reduced in Sarigol at 10 and 15% of PEG. Drought stress significantly increased seedling fresh weight in RGS003. Sarigol accumulated higher amounts of protein as compared to RGS003. At all PEG concentrations, the soluble sugars contentwas higher in Sarigol as compared to control. Total phenol content was enhanced at higher drought level (15%) while flavonol content increased at lower level (5%) in both cultivars. Phenylalanine ammonia-lyase (PAL) activity and its relative expression were increasedin RGS003 at 10% of PEG. Overall, RGS003 cultivar had more capacity to tolerate drought stress than Sarigol cultivar.. Manuscript profile

Acclimation of plants to stress conditions depends upon activation of cascade of signaling networks involved in stress perception. Regulation of antioxidative system to maintain a balance between the overproduction of reactive oxygen species and their scavenging to keep them at signaling level has been previously documented. Recently, role of triazolic compounds like penconazole, paclobutrazole, triadimefon, and hexaconazole in the regulation of metabolic network under stress conditions has emerged through crosstalk between chemical signaling pathways. Thus, stress signaling and metabolic balance is an important area with respect to increase crop yield in adverse environmental conditions. This review outlines the recent advances on improvement in stress resistance by various triazolic compounds, aiming to identify new mechanisms of stress tolerance, and therefore, to contribute sustainable crop yield under stress to bring some potential practical utilization in the future. Researches have revealed that triazolic compounds, to some extent, help plants to cope with adverse environmental conditions. Therefore, these compounds could be used for improvement of plant growth and productivity in such severe conditions. Manuscript profile