Current study determined the effects of different cultivation media and some factors on in vitro callus induction and shoot regeneration of Pakaumpuel rice (Oryza sativa L.), the Thai rice landrace. Pakaumpuel’s dehusked seeds were surface sterilized by 20% Sodium hypoclorite for 20 mins before washed and cultured on Murashige and Skoog (MS) medium in various concentrations of BAP (0, 0.1, 0.5 and 1 mg/l) and 2,4-D (0, 1, 2 and 3 mg/l) and cultivated in off -light or dark cycle condition for 15 days. Results showed that MS medium with 2 mg/l 2,4-D incubated in light condition provided the highest callus induction percentage (80 %). For shoot regeneration, calli were desiccated by using silica gel for 0, 30, 90 and 180 minutes prior to culture on MS medium with 1 mg/l NAA and various concentrations of BAP (0, 1, 2, 3 and 4 mg/l) for 30 days. The results revealed that desiccation periods had no effect on regeneration percentage and number of shoot per callus, but had effects on shoot length and number of leaves per shoot. Therefore, MS medium with 1 mg/l NAA and 3 mg/l BAP induced the highest regeneration percentage (53.33 %) and number of shoot per callus (4.40 shoots), while the longest shoot (12.82 cm) and the highest number of leaves per shoot (3.00 leaves) were found on the culture on this medium after desiccation for 90 minutes. This discovery can be applied for micropropagation of other Thai rice landraces.
Background Pokeweed (Phytolacca americana L.) is regarded as an invasive plant in many parts of the world but possesses therapeutic characteristics used for antitumor and rheumatism treatment. This study investigated the effects of auxins and four explants on pokeweed callus induction. The effects of cytokinins and combinations between cytokinins and NAA on shoot and root induction were also studied. TPC, TFC and antioxidant activity of calli were screened and compared with other pokeweed plant parts. Methods Four explants were used to induce callus using 2,4-D and IBA at 1, 2, 3 and 4 mg/l for each auxin. Direct shoot organogenesis from nodal explants was investigated using BAP, kinetin and TDZ (1, 2 and 4 mg/l for each cytokinin). Combined effects between cytokinins and NAA at 0.1, 0.2 and 0.3 mg/l were further simultaneously estimated with root induction. Calli derived from the leaves were compared with other plant parts for TPC, TFC and antioxidant activity using the Folin-Ciocalteu, AlCl3 colorimetric assay and DPPH assays, respectively. Results Results showed that MS medium containing 2 mg/l 2,4-D induced callus formation on leaf explants that provided highest fresh and dry weights. Three types of synthetic cytokinins as kinetin, TDZ and BAP were used for direct shoot organogenesis from pokeweed nodes. MS medium containing 2 mg/l kinetin was effective in stimulating normal shoots, with the largest number of shoots and leaves and the longest shoots. The combination between cytokinins and NAA showed no positive effect on shoot and root induction from pokeweed nodal explants. For TPC and TFC determination, pokeweed seeds and leaves possessed the highest phenolic and flavonoid contents, respectively. Highest phenolic content of pokeweed seeds led to lowest IC50 by DPPH assay. Phenolic content was higher than flavonoid content. Conclusion Results suggested promising conditions for callus induction. Leaf explants cultured on MS medium with 2 mg/l 2,4-D and nodal explants cultured on MS medium with 2 mg/l kinetin provided the largest number of normal shoots and leaves. NAA did not show positive effects on shoot and root induction when combined with cytokinins. Chemical constituent screening indicated that seeds and leaves provided highest TPC and TFC, respectively, while pokeweed calli contained higher phenolic than flavonoid content. This is the first report describing chemical constituent screening and antioxidant activity of calli and other parts of the pokeweed plant. Results provided significant information to further enhance bioactive compound contents of pokeweed calli using elicitation methods.
Background and Objective: Salinity is abiotic stress that affects rice growth and results in lower yields. This research studied the effects of salinity on Tubtim Chumphae rice growth. Materials and Methods: Seedlings were cultivated for 35 days in the soil before being stressed by salinity (0, 25, 50, 75 and 100 mM NaCl) for 4 weeks. Growth performance and some physiological traits were recorded weekly for 4 weeks. Results: Under salinity stress, fresh and dry weight of shoot and root, relative dry weight, plant length and root length all decreased as salt solution concentration increased. Electrolyte leakage percentage and malondialdehyde content increased when rice was exposed to the salt solution for 4 weeks, indicating that high salinity damaged the lipid membrane. The PCA results revealed positive correlations among growth parameters that negatively correlated with MDA content and electrolyte leakage. The HCA results confirmed the PCA biplot showing decreasing expression of growth parameters with rising salt stress levels, while MDA content and electrolyte leakage continuously increased. Results suggested MDA content and electrolyte leakage as indicators for salt stress in Tubtim Chumphae rice at seedling and early vegetative stage. Conclusion: Findings in this study indicated that Tubtim Chumphae rice plants can grow in slight to moderate salinity soil. Results will deliver advantageous data that can be integrated with additional agronomical characters in rice growth or breeding plans for abiotic stress-tolerant cultivars improvement.
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