seyedeh batool hassani

Onosma pachypoda Boiss. is a medicinal plant and belongs to Boraginaceae family. Enhancement of secondary metabolites using modern biotechnological methods such as tissue culture and hairy root induction by Agrobacterium rhizogenes can be important. In the present study, hairy root induction by A. rhizogenes strain A4 on the callus of O. pachypoda was examined via dry and immersion methods under different spectral LED lights. The effect of LED lights was also investigated on the concentration of flavonoid content in inoculated callus. The results showed that the highest percentage (50%) of hairy root induction was obtained by immersing the callus in the suspension of A. rhizogenes under dark conditions. The highest flavonoid content was observed in inoculated callus under blue LED light and dark conditions. Therefore, the immersion method is a suitable method for inoculation of callus to induce hairy roots in the plant. It seems that using of different spectral LED lights also affects flavonoid content in the callus of O. pachypoda.

Seed priming has a significant effect on seed germination and improves the establishment of crops. In this study, rice seeds (Oryza sativa cv. Shiroodi L.) were primed by different concentrations (0, 0.025, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 g/l) of Nostoc commune Vauch aqueous extract. Furthermore, seed germination rate, percentage, and seedling growth were examined. The results showed that N. commune extract had a significant positive effect on increasing the percent and rate of seed germination. Indeed, the length of roots and shoots in seedlings obtained from primed seeds with N. commune extract increased compared to those of the seedlings from primed seeds with water. Additionally, the highest seed germination percent and seedling length were obtained by 0.025 g/l N. commune extract. Based on the results, seed germination and seedling growth were not affected by seed priming with N. commune extract at concentrations of more than 0.1 g/l. Therefore, sowing rice seeds with a low concentration of N. commune extract can improve seed germination and seedling establishment.

Heavy metals stress (cadmium stress) is one of the most important factors which lead to reduction of plant growth and productivity of agricultural products. One of the plant responses to heavy metal stresses is changes in polyamines contents in plants. Regarding the economic importance of maize, the effects of cadmium stress on seed germination, plant growth parameters and polyamines contents (putrescin, spermidine and spermine) were investigated in 3 days-old seedlings and the roots after 6, 12, 15 and 20 days. Polyamines analysis was performed by HPTLC. The results indicated that cadmium stress in maize is the cause of delay in seed germination and decreased plant growth parameters. Cadmium stress increased the total polyamine content as a result of 35% increase of the putrescine in 3 days-old seedlings. In general, a significant increase of putrescine was observed in the roots of the 6 days-old- and 15 days-old plants under cadmium stress. While the highest amount of spermine and spermidine was in the root of the 12 days-old plants under cadmium stress. Roots of the 15-days-old plant showed the highest content and translocation factor of cadmium. These results suggest that the changes in the amount of polyamines in maize plant under cadmium stress depend on the cadmium absorption by the plant root and the type of polyamines.

According to previous studies, salicylic acid decreases the hyperhydricity in Thymus daenesis and this event might be due to the effect on polyamines metabolism. Polyamine oxidase enzyme catabolizes the polyamines in the cell and one of its byproducts is hydrogen peroxide (H2O2). Purpose of this study is analyses of salicylic acid effect on polyamine oxidase activity in thymus daenensis callus. In this study, the activity of polyamine oxidase, content of H2O2, and responses of enzymatic antioxidant including catalase and peroxidase was measured. Results showed that salicylic acid (concentrations of 10 and 20 µM) caused an increase in polyamine oxidase activity in a dose dependent manner. In callus under salicylic acid treatment (20 µM) a decrease in soluble peroxidase activity and an elevated H2O2 content was observed. Increase of H2O2 might be due to the influence of salicylic acid on polyamine oxidase and peroxidase activities. While variations in H2O2 levels resulted in no changes of catalase activity. Regulation of H2O2 level by salicylic acid through its effect on polyamine oxidase activity might contribute to ROS homeostasis, which is necessary for in vitro developmental processes in plant cells.

Cyanobacteria are oxygenic, photosynthetic prokaryotes with unique potential to enhance plant growth, development, and productivity. The aim of this study was to evaluate the possible beneficial effects of Phormidium sp. ISC108 on seed germination, seedling growth criteria and photosynthetic efficiency of maize. Phormidium was applied to soil via irrigation whereas control group was irrigated via sterilized water. A significant promotion in the seed germination was observed in Phormidium treated Maize seeds. Similarly, Seedling growth indices of treated plants including biomass production, plant heights and leaf area significantly enhanced. Chlorophyll content as well as chlorophyll a fluorescence kinetics was also positively influenced by Phormidium application. Quantum yield of photosynthesis, primary photochemical reactions, rate of exiton transfer to electron transport chain, yield of electron transport and performance index of photosynthetic apparatus significantly increased in response of Phormidium application in soil. However, values of thermal dissipation of absorbed light showed a significant reduction as a result of Phormidium treatment. Considering remarkable growth promoting properties, Phormidium sp. may offer a feasible economical and environmental-friendly candidate as bio-fertilizer in sustainable maize production.