Journal of Medicinal Plants Biotechnology

Abstract To investigate the effect of proline and gamma-aminobutyric acid on the quantitative and qualitative traits of medicinal plant chamomile (Matricaria chamomilla L.) under water deficit stress, an experiment was conducted according to split plots design with a completely randomized block arrangement with four replications during the spring and summer of 2024 in the research greenhouse at the University of Zanjan. The main factor consisted of two irrigation levels (70 and 100% of field capacity) and the subplots included foliar applications of two levels of proline (0.5 and 1 mM), gamma-aminobutyric acid (0.5 and 1 mM) and control treatment (distilled water).
The results showed that the highest chlorophyll a content (1.40 mg/g fresh weight) was achieved under 100% field capacity irrigation combined with 1 mM proline. Foliar application of 0.5 mM proline under 70% irrigation level resulted in the highest phenolic content (4.78 mg gallic acid/g dry weight) and the greatest total antioxidant activity (51.75%). The maximum flavonoid content (1.49 mg quercetin/g dry weight) was observed with 0.5 M GABA treatment. Additionally, the highest thousand-seed weight (148 mg) was recorded under full irrigation (100% field capacity) with 1 mM proline, compared to the control. Overall, the combined application of 0.5 mM proline and GABA was most effective in mitigating the adverse effects of drought stress on chamomile.

Abstract Taxanes are diterpenoid compounds with medicinal properties, obtained from various yew species (Taxus baccata). Among them, paclitaxel (Taxol) is the most important and is widely used in cancer chemotherapy. Due to the extremely low yield of taxol in yew plants, alternative production methods are necessary. Callus and plant cell culture present an environmentally friendly alternative for producing taxol and related taxanes. To enhance taxane production in cultured callus, various strategies such as elicitation can be employed. In this study, calli were treated with the elicitors chitosan (10, 30, and 50 mg/L) and jasmonic acid (50, 100, and 150 µM) in triplicate. The calli were maintained in B5 medium supplemented with 4 mg/L 2,4-D, 1 mg/L kinetin, 0.5 mg/L gibberellin, 10 mL/L antioxidant, 30 g/L sucrose, and 7 g/L agar, and incubated in darkness at 25°C for 21 days. The levels of five major taxanes: taxol, 10-deacetylbaccatin III, baccatin III, 10-deacetyltaxol, and cephalomannine were quantified using HPLC. The results indicated that the highest taxol and 10-deacetylbaccatin III contents were achieved with 100 µM jasmonic acid treatment. The maximum baccatin III yield was observed with 50 mg/L chitosan, while 10-deacetyltaxol production was highest with 50 µM jasmonic acid. Interestingly, the highest cephalomannine accumulation was found in the control (untreated) calli.

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