Changes in growth parameters, carbon assimilation efficiency, and utilization of 14CO2 assimilate into alkaloids in plant parts were investigated at whole plant level by treatment of Catharanthus roseus with gibberellic acid (GA). Application of GA (1 000 g m-3) resulted in changes in leaf morphology, increase in stem elongation, leaf and internode length, plant height, and decrease in biomass content. Phenotypic changes were accompanied by decrease in contents of chlorophylls and in photosynthetic capacity. GA application resulted in higher % of total alkaloids accumulated in leaf, stem, and root. GA treatment produced negative phenotypic response in total biomass production but positive response in content of total alkaloids in leaf, stem, and roots. 14C assimilate partitioning revealed that 14C distribution in leaf, stem, and root of treated plants was higher than in untreated and variations were observed in contents of metabolites as sugars, amino acids, and organic acids. Capacity to utilize current fixed 14C derived assimilates for alkaloid production was high in leaves but low in roots of treated plants despite higher content of 14C metabolites such as sugars, amino acids, and organic acids. In spite of higher availability of metabolites, their utilization into alkaloid production is low in GA-treated roots. and N. K. Srivastava, A. K. Srivastava.
Genotypic variations were observed among 6 variants and an indigenous one as a control. An efficient genotype OCD(L) of Ocimum sanctum had the greatest content of chlorophylls [2.15 g kg-1(FM)], Chl a/b ratio of 1.86, net photosynthetic rate of 0.72 mg(CO2) m-2 s-1, and 1.56 % oil formation. Methyl chavicol formed 50.31 % of total oil in OSP-6 genotype, which had also maximum peroxidase activity [ΔOD 2.4 mg-1(protein)] and maximum production of eugenol (30.44 % of total oil). We found an oxido-reducible reaction of peroxidase and high bands of peroxidase isoenzymes in this OSP-6 genotype for the formation of monoterpene essential oil(s) and possibly the major constituents of eugenol through the high production of photosynthates. and A. Misra ... [et al.].
Partitioning of exogenously supplied U-14C-saccharose into primary metabolic pool as sugars, amino acids, and organic acids was analyzed and simultaneous utilization for production of alkaloid by leaf, stem, and root in twigs and rooted plants of Catharanthus roseus grown in hydroponic culture medium was determined. Twigs revealed comparable distribution of total 14C label in leaf and stem. Stems contained significantly higher 14C label in sugar fraction and in alkaloids [47 kBq kg-1(DM)] than leaf. In rooted plants, label in 14C in metabolic fractions in root such as ethanol-soluble, ethanol-insoluble, and chloroform-soluble fractions and in components such as sugars, amino acids, and organic acids were significantly higher than in stems and leaves. This was related with significantly higher content of 14C in alkaloids in stems and leaves. 14C contents in sugars, amino acids, and organic acids increased from leaf to stem and roots. Roots are the major accumulators of metabolites accompanied by higher biosynthetic utilization for alkaloid accumulation. and N. K. Srivastava, A. K. Srivastava.
Partitioning of current photosynthates towards primary metabolites and its simultaneous incorporation in leaf alkaloids was investigated in developing leaves of medicinally important Catharanthus roseus. Of the total 14CO2 assimilated, the leaves at positions 1-6 fixed 8, 22, 25, 19, 13, and 8 %, respectively, and stem 3 %. Leaf fresh mass, chlorophyll content, and CO2 exchange rate increased up to the third leaf. The total alkaloid content was highest in young actively growing leaves, which declined with age. Total 14C fixed and its content in ethanol soluble fraction increased up to the third leaf and then declined. The 14C content in primary metabolites such as sugars and organic acids was also highest in the 3rd leaf. The utilization of 14C assimilates into alkaloids was maximum in youngest leaf which declined with leaf age. Hence the capacity to synthesize alkaloids was highest in young growing leaves and metabolites from photosynthetic pathway were most efficiently utilized and incorporated into alkaloid biosynthetic pathway by young growing leaves. and N. K. Srivastava ... [et al.].
Culturing geranium at different doses of Zn from 0-1.0 g m-3 (Zn0 to Zn1.000) revealed that Zn is an antioxidant promoter, apart from its micronutrient essentiality. Zn0.250 was the critical concentration for maximum content (0.21 %) of total essential monoterpene oil(s). At Zn0.005-Zn0.250, net photosynthetic rate, and contents of chlorophyll and essential monoterpene oil(s) were affected. The maximum peroxidase activity was obtained at Zn0.250, with the production of biomolecule geraniol. We found an oxido-reducible reaction of Zn in the formation of monoterpene essential oil(s) and possibly major constituents of geraniol. and A. Misra ... [et al.].