To date enormous attempts have been devoted to improve Taxol production exploiting various methodologies from bioprocess engineering to biotechnological and synthetic approaches. We have developed a 2-stage suspension cell culture of Taxus baccata L. using modified B5 medium in order to improve cell growth as well as productivity. After callus induction and cell line selection, B5 medium was supplemented with vanadyl sulfate (0.1 mg/l), silver nitrate (0.3 mg/l) and cobalt chloride (0.25 mg/l) at the first day of stage I culture to maximize cell growth. This medium was further supplemented with sucrose (1%) and ammonium citrate (50 mg/l) on day 10 and sucrose (1%) and phenylalanine (0.1 mM) on day 20 (i.e., biomass growth medium). At stage II (day 25), two different concentrations of several elicitors such as methyl jasmonate (10 or 20 mg/l), salicylic acid (50 or 100 mg/l) and fungal elicitor (25 or 50 mg/l) were added to the biomass growth medium with the aim of improving cellular productivity. For morphological analysis, microscopic inspection was carried out during cultivation. Cell-associated and extracellular amount of Taxol were detected and measured using HPLC methodology. At stage I, overall Taxol amount of biomass growth medium was 13.75 mg/l (i.e., 5.6-fold higher than that of untreated B5 control). At stage II, treated cells with methyl jasmonate (10 mg/l), salicylic acid (100 mg/l) and fungal elicitor (25 mg/l) produced the highest amount of Taxol (39.5 mg/l), which is 16-fold higher than that of untreated B5 control (2.45 mg/l). Microscopic analyses of Taxus cells in suspension cultures showed various positional auto-fluorescence showing direct correlation with Taxol production. Our studies revealed that intervallic supplementation of B5 medium with combination of biomass growth factors at stage I and mixture of elicitors at stage II could significantly increase Taxol production. Thus, we suggest that the exploitation of this methodology may improve the production of Taxol since demands for Taxol pharmaceuticals are increasingly growing and resource paucities have limited its direct harvesting from Taxus trees.
Productivity of sunflower (Helianthus annuus L.), the fourth most important oilseed crop, is strongly dependent on water availability. To search for genetic variation in the ability of roots to grow into drying soil, 16 sunflower lines were screened in 2 years field experiments by imposing drought stress at flowering stage. The results differentiated RGK 21 and BGK 329 as the most sensitive and tolerant lines respectively. The time course physiological assay of these lines at seedling stage revealed roots as the most affected organ 6 days after imposing drought stress. A proteomics approach was adapted for investigating of differential changes in roots proteome under contrasting moisture regimes. Protein spots with significant changes in protein abundance were identified by nano LC-MS/MS. The results indicated that under drought stress relative abundance of metabolism related proteins were decreased in both sensitive and tolerant lines. Abundance of energy and disease/defence related proteins were decreased in the sensitive but increased in the tolerant line. The results indicate that changes in energy usage, water transport and ROS scavenging are important mechanisms for maintaining root growth as the soil dries.
The study was performed to determine as to whether antioxidant potential (enzymatic and non-enzymatic antioxidants) as well as some other attributes could be used as potential drought resistance markers in two maize lines (B 73 and MO 17). Under water deficit conditions, growth traits, relative water content (RWC), chlorophyll a, total chlorophyll and carotenoids as well as grain yield decreased significantly in both lines compared to those under control conditions. In contrast, water deficit caused a significant increase in the activities of superoxide dismutase (SOD) and catalase (CAT) isozymes as well as levels of glycine betaine (GB), proline and malondialdehyde (MDA), whereas total phenolics, total soluble protein, H 2 O 2 , chlorophyll b, chlorophyll a/b ratio, anthocyanin and peroxidase (POX) isozyme activity remained unaffected in both maize lines. Although water deficit stress induced oxidative stress in both maize lines, the enzymatic and non-enzymatic antioxidants and key organic osmolytes increased significantly in both maize lines. For example, SOD isozyme activities, and GB and proline contents were considerably greater in relatively drought resistant MO 17 than those in relatively drought sensitive B 73. However, in contrast, CAT activity was higher in B 73. Overall, SOD isozyme activities, and GB and proline contents were found to be potential biochemical indicators of drought resistance in the two maize lines used in the present study.
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