Stevia rebaudiana (Bertoni) is a non-caloric sweetener belonging to Asteraceae family. Stevia compounds such as steviol glycosides (SGs) are 200 times sweeter than sugar. Stevioside and rebaudioside A are the two major steviol glycosides. Nitrogen is an essential element for plant growth and development. In this study the effects of nitrogen influenced by different concentrations of NH4NO3 (0, 825 and 1650 mg/l) and KNO3 (0, 950 and 1900 mg/l) is examined in MS medium. To analysis the UGT74G1 and UGT76G1 genes expression, involved in the synthesis of SGs, RT-qPCR technique was performed. Data showed that there were significant differences between all media. The shoot length, seedlings dry weight and leaf fresh weight of stevia increased with applying NH4NO3 along with KNO3. The highest expression of UGT74G1 gene, was observed in plantlets grown on MS medium with 0 mg/l NH4NO3 and 950 mg/l KNO3 (1.291 total lab unit) but the highest expression of UGT76G1 gene, was observed in plantlets grown on MS medium added by 1650 mg/l NH4NO3 +950 mg/l KNO3 (1.08 total lab unit). Moreover, the lowest value of UGT74G1 gene expression were revealed in MS medium added by 1650 mg/l NH4NO3 +0 mg/l KNO3 (0.80 total lab unit) and the lowest values of UGT76G1 gene expression seen in MS medium with 0 mg/l NH4NO3 +950 mg/l KNO3 (0.85 total lab unit) concentrations. The results of this study could be valuable in stevia breeding programs through glycosides biosynthesis pathways.
Aim: This study aimed to access the rapid and improved propagation protocol production of Zamifolia plant using tissue culture. Material and Methods: For callus formation and regeneration, two independent factorial experiments were carried out in a completely randomized design with 3 replications in the tissue culture laboratory of the National Research Institute of Flowers and Ornamental Plants in 2018. In the first experiment, to induce callogenesis, 2,4-D (0, 1, 2, and 4 mg/l) and BA (0, 1 and 2 mg/l) were used. In the second experiment, or regeneration of explants, NAA (0 and 0.5 mg/l) and BA (0, 0.5, and 1 mg/l) were applied. Results:The results of the callogenesis experiment showed that a modified basal MS medium with concentration of 2 mg/l BA and 1 mg /l 2,4-D produced the best callus with 85% regeneration. At the regeneration stage of the callus, 0.5 mg/l BA and 0.5 mg NAA produced the highest number of seedlings and regenerated tubers (90%). Subsequently, single tuber seedlings were successfully adapted to 80%-90% in the cocopeat and perlite substrates. Conclusion:The results were successful and could be possible to achieve the callogenesis and regeneration of Zamifolia plant with the formula presented and recommend as practical a protocol for commercial micropropagation of this valuable ornamental plant.
This experiment was conducted to assess the quantitative and qualitative changes in soluble proteins as well as some chlorophyll fluorescence parameters in the leaves of a winter canola (Brassica napus L., cv. Licord) under continuous low temperature. Over the experiment, seedlings were initially grown at 15/10 °C (d/n). At fourth fully expanded leafy stage (day 30), a part of the plants were transferred to 4/2°C for 4 weeks. Plants were sampled for protein extraction from leaves in which chlorophyll fluorescence parameters (F o , F v , F m , F v/ F o, F m/ F o, F v /F m , F o´, F V´, F m´ and some other calculated) were also measured. The results showed a clear increase in soluble proteins quantity caused by cold treatment. The enhancements appeared abruptly following the cold exposure to 4°C and lasted. The electrophoretic protein patterns showed changes in the intensity of some polypeptides, besides, induction a new probable protein weighing 47-kW in response to cold treatment. Cold-triggered reduction in maximum quantum yield of PSII (F v /F m) was connected especially with drastic decreasing F v and F m. Interestingly, high quantitative amounts of soluble proteins along with induction of the new probable polypeptide induced at cold temperature, were attributed to low deduction of maximum quantum yield of PSII. Additionally, more imperative chlorophyll fluorescence parameters changed e.g. qP, NPQ, qL, Y(II) or ф PSII etc at light. Nowadays, radar charts or spider plots are the most sophisticated multivariate statistical tools representing physiological responses of plants to abiotic stress conditions or even morphophysiological studies of plants. In rapeseed many researches performed by applying the radar charts for low temperature stresses and interpreted their effects more advancely than common statistical tools. We observed a good representation of the chl fluorescence parameters fluctuations using radar plots. Overall, cold-induced soluble proteins accumulated after longer cold-acclimation, can contribute in photosynthetic apparatus protection against low-temperature damages.
Stevia rebaudiana Bertoni belongs to Asteraceae family that leaves 200-300 times sweeter than sugar. Low seed fertility is one of the most important problems in Stevia production. So, Plant tissue culture is an efficient method for mass propagation of Stevia. In this research, we studied the effect of various concentrations of nitrogen on some morphological traits of stevia under in vitro conditions. We used axillary nodes as explants and they were cultured on Murashige and Skoog (MS) medium containing inorganic nitrogen sources i.e. NH4NO3(0, 825 and 1650 mg/l), KNO3(0, 950 and 1900 mg/l) were observed. The cultures were kept for 4 weeks at a temperature of 25±2°C with a photoperiod of 16/8 hour low light/dark each day. Maximum shoot length (89.33 mm), dry weight of plants (0.10 mg) and leaf fresh weight (0.42 mg) was observed on MS medium with 1650 mg/l NH4NO3 and 950 mg/l KNO3. Minimum shoot length (6.13 mm), root length (6.60 mm), leaf number (4.26), leaf dry weight (0.01 mg), leaf fresh weight (0.05 mg), total dry and fresh weight (0.02 and 0.15 mg) and growth rate was observed on a MS medium without nitrogen sources. Moreover, presence of nitrogen sources increases both shooting and rooting in Stevia rebaudiana Bertoni.
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