Assessment of diversity among populations of Rauvolfia serpentina Benth. Ex. Kurtz. from Southern Western Ghats of India, based on chemical profiling, horticultural traits and RAPD analysis.

Genetic, morphological and chemical variations of ten natural populations of Rauvolfia serpentina Benth. Ex. Kurtz. from Southern Western Ghats of India were assessed using RAPD markers reserpine content and morphological traits. An estimate of genetic diversity and differentiation between genotypes of breeding germplasm is of key importance for its improvement. Populations were collected from different geographical regions. Data obtained through three different methods were compared and the correlation among them was estimated. Statistical analysis showed significant differences for all horticultural characteristics among the accessions suggesting that selection for relevant characteristics could be possible. Variation in the content of Reserpine ranges from 0.192 g/100 g (population from Tusharagiri) to 1.312 g/100 g (population from Aryankavu). A high diversity within population and high genetic differentiation among them based on RAPDs were revealed caused both by habitat fragmentation of the low size of most populations and the low level of gene flow among them. The UPGMA dendrogram and PCA analysis based on reserpine content yielded higher separation among populations indicated specific adaptation of populations into clusters each of them including populations closed to their geographical origin. Genetic, chemical and morphological data were correlated based on Mantel test. Given the high differentiation among populations conservation strategies should take into account genetic diversity and chemical variation levels in relation to bioclimatic and geographic location of populations. Our results also indicate that RAPD approach along with horticultural analysis seemed to be best suited for assessing with high accuracy the genetic relationships among distinct R. serpentina accessions.

Accelerated reactive oxygen scavenging system and membrane integrity of two Panicum species varying in salt tolerance.

Plant exhibits various patterns of survival under salinity and their growth and development depend on their capacity to overcome the stress. Present investigation was focused on the response and regulation of the antioxidant defense system and the level of lipid peroxidation in Panicum miliacium and Panicum sumatrense under salt treatments. NaCl stress was imposed for 20 days after sowing of two Panicum species. The changes in the antioxidant enzyme activity like superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase and the rate of lipid peroxidation level in terms of malondialdehyde (MDA) were recorded in both Panicum species. A great correlation exists between the antioxidant enzymes and lipid peroxidation. The defense mechanism activated in Panicum species studied was confirmed by the increased antioxidant enzyme activities under progressive NaCl stress. MDA content remained close to control at moderate NaCl concentrations and increased at higher salinities. Although lipid peroxidation increased in both Panicum species under salt stress the percent of increase was low in P. sumatrense indicating its salt-tolerant nature. Another possible conclusion is that improved tolerance to salt stress may be accomplished by increased capacity of antioxidative system.

Preliminary study on the antimicrobial activity of Enicostemma littorale using different solvents.

OBJECTIVE: To study the antimicrobial activity of Enicostemma littorale (E. littorale) using different solvents. METHODS: Chloroform, methanol and acetone extracts of different parts of E. littorale (leaf, stem and root) were evaluated for antimicrobial activity using disc diffusion method against some gram-negative species such as Escherichia coli, Klebsiella pnemoniae, Pseudomonas aeruginosa, Salmonella typhi and gram-positive species Staphylococcus aureus, Bacillus cereus, Bacillus subtilis and two fugal species viz., Aspergillus fumigates and Aspergillus flavus. RESULTS: The chloroform extracts showed the highest antibacterial activity. Among leaf, stem and root extracts, the stem extracts showed maximum antibacterial activity. All of the used extracts had no significant antifungal activity against Aspergillus fumigates and Aspergillus flavus. The chloroform stem extract showed highest activity (about 20 mm inhibition zone) against Bacillus subtilis (at 500 mg/mL) followed by the methanolic stem extract which showed highest activity against the same organism. The lowest antibacterial activity was observed by the acetone leaf extract (about 8 mm inhibition zone) against Escherichia coli. CONCLUSION: The findings of the study indicate littorale could also be a new source for antibiotics discovery.

Salinity induced changes in photosynthetic pigment and antioxidant responses in Sesuvium portulacastrum.

The production of leaf and root antioxidant changes when exposed to saline conditions were investigated in the perennial halophyte Sesuvium portulacastrum L. Plants were grown with a nonsterilized soil and sterilized soil with 50 and 100% of sterilized seawater on 25, 55 and 85 Days After Planting (DAP). The plants were harvested on 30th, 60th and 90th DAP and used for analyzing the photosynthetic pigments, antioxidant enzyme activities viz., Superoxide dismutase (SOD; EC1.15.1.1) Ascorbate peroxidase (APX, EC 1.11.1.11) and non enzymatic antioxidant contents like ascorbic acid, alpha-tocopherol, reduced glutathione were determined. Plants exposed to salinity, either alone (SSW) sterilized seawater/unsterilized soil (USS) along with higher pigments, antioxidative enzymes and Na+ ions response. This tendency was generally more marked in SSW/USS plants when compared to SSW/SS plants. The concentration of SSW/SS was negatively correlated with the antioxidative capacity of the plant, either enzymatic or non enzymatic and K+ ions. These data suggest that the enhancement of the antioxidative response is of crucial significance for S. portulacastrum plants growing under saline conditions.

Endogenous hormonal and enzymatic responses of Catharanthus roseus with triadimefon application under water deficits.

The effect of triadimefon was investigated in a medicinal plant, Catharanthus roseus subjected to water deficit stress. The abscisic acid (ABA) level, DNA and RNA contents and activities of ATPase and protease were found varying in different parts of the plants under treatment. Drought treatment increased the ABA level more than twofold in all parts of the plants. TDM treatment to the drought stressed plants showed highest contents. In roots, stem and leaves, drought stress caused a decrease in the DNA and RNA contents when compared with control and other treatments. TDM treatment with drought increased the nucleic acid contents to the level of the control roots. The activity of ATPase and protease were increased under drought treatment and lowered due to TDM applications. This information could be useful in the field of soil water deficits reclamation efforts by using plant growth regulators.

Osmoregulation and antioxidant metabolism in drought-stressed Helianthus annuus under triadimefon drenching.

A pot-culture experiment was conducted to estimate the ameliorating effect of triadimefon (TDM) on drought stress in sunflower (Helianthus annuus L.) plants. The plants were subjected to 3-, 6-, and 9-day-interval drought (DID) stress and drought stress with TDM @ 15 mg l(-1) and 15 mg l(-1) TDM alone from the 30th day after sowing (DAS). One-day-interval irrigation was kept as control. The plant samples were collected on and separated into root, stem and leaf for estimating the amino acid (AA), proline (PRO) and glycine betaine (GB) contents and the activities of antioxidant enzymes. Individual and combined drought stress and TDM treatments increased AA, PRO and GB contents, superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), and polyphenol oxidase (PPO) activities when compared to control. From the results of this investigation, it can be concluded that the application of TDM caused a partial amelioration of the adverse effects of drought stress by its influence on quaternary ammonium compounds and antioxidant potentials in H. annuus plants.

Growth and photosynthetic pigments responses of two varieties of Catharanthus roseus to triadimefon treatment.

Triadimefon, potential fungicide cum plant-growth retardant was used in this study to investigate its effect on the growth and the photosynthetic pigment contents of two varieties of Catharanthus roseus (L.) G. Don. The plants of both varieties were subjected to 15 mg l(-1) triadimefon treatment by soil drenching 30, 45, 60, and 75 days after planting (DAP). Plants were uprooted on 90 DAP, and morphological parameters, like plant height, number of leaves, leaf area, root length and fresh and dry weights were determined. The photosynthetic pigments, like chlorophylls a and b, total chlorophyll, carotenoids, floral pigment, anthocyanin, were extracted and estimated. It was observed that plant height, number of leaves and leaf area were decreased and that root length, fresh and dry weights were increased under triadimefon treatment. The photosynthetic and floral pigments were increased under triadimefon treatment in both varieties. The results suggest that the application of this plant-growth retardant (triadimefon) has favourable effects on the reduction of plant height; it can thus be used for replacing manual hand pruning and for improving floral and vegetation colour in bedding plants like C. roseus.

Differential responses in water use efficiency in two varieties of Catharanthus roseus under drought stress.

Two varieties, rosea and alba, of Catharanthus roseus (L.) G. Don. were screened for their water use efficiency under two watering regimes, viz. 60 and 100% filed capacity in the present study. Drought stress was imposed at 60% filed capacity from 30 to 70 days after sowing, while the control pots were maintained at 100% filed capacity throughout the entire growth period. Leaf area duration, cumulative water transpired, water use efficiency, net assimilation rate, mean transpiration rate, harvest index, biomass and yield under the water deficit level were measured from both stressed and well-watered control plants. Water use efficiency significantly increased in both varieties under water stress. Drought stress decreased leaf area duration, cumulative water transpired, net assimilation rate, mean transpiration rate, harvest index, and biomass yield in both varieties studied. Among the varieties, rosea variety showed the best results.

Alterations in lipid peroxidation, electrolyte leakage, and proline metabolism in Catharanthus roseus under treatment with triadimefon, a systemic fungicide.

Triadimefon (TDM), a systemic fungicide with non-traditional plant-growth regulator properties, was administered to Catharanthus roseus (L.) G. Don. plants in order to determine its effects on oxidative injury in terms of H2O2 content, lipid peroxidation (LPO), electrolyte leakage (EL), protein and amino acid contents, as well as proline metabolism. The LPO, estimated as thiobarbituric acid-reactive substances (TBARS), decreased under TDM treatment. It was found that H2O2 and EL were reduced under TDM treatment when compared to control. TDM treatment caused a significant increase in the protein and amino acid contents. Glycine betaine (GB) and proline (PRO) significantly accumulated in C. roseus under stress arisen from fungicide applications. Proline oxidase (PROX) activities reduce the PRO content and gamma-glutamyl kinase (gamma-GK) accelerates the synthesis of PRO. Under TDM treatment, the activity of PROX decreased and the gamma-GK activity increased. From our results, it is suggested that fungicide triadimefon causes activation of metabolic processes in the medicinal plant Catharanthus roseus. These findings are of great significance for the cultivation of this medicinal plant, as it was previously reported that TDM causes an enhancement of antioxidant metabolism and ajmalicine production in C. roseus.

Responses of antioxidant potentials in Dioscorea rotundata Poir. following paclobutrazol drenching.

The effect of paclobutrazol (PBZ) treatments on the antioxidant metabolism of white yam (Dioscorea rotundata Poir.) was investigated in the present study. PBZ @ 15 mg l(-1) plant(-1) was given to plants by soil drenching, 30, 60, and 90 days after planting (DAP). The non-enzymatic antioxidant contents like ascorbic acid (AA), reduced glutathione (GSH) and alpha-tocopherol (alpha-toc), activities of antioxidant enzymes like superoxide dismutase (SOD), ascorbate peroxidase (APX), polyphenol oxidase (PPO) and catalase (CAT) were extracted and assayed on 100 DAP from leaf, stem and tubers of both control and PBZ treated plants. It was found that PBZ has a profound effect on the antioxidant metabolism and caused an enhancement in both non-enzymatic and enzymatic antioxidant potentials under treatments in white yam. Our results have good significance, as this increase the innate antioxidant potential of this food crop, which is helpful to satisfy the needs of antioxidants in diet and thereby make it an economically important food crop.

NaCl as a physiological modulator of proline metabolism and antioxidant potential in Phyllanthus amarus.

Some medicinal plants need to be cultivated commercially in order to meet the ever-increasing demand for medicinal plants for the indigenous systems of medicine as well as for the pharmaceutical industry; in this regard, it seems significant to test the important medicinal plants for their salt-tolerance capacity, with a view to exploiting the saline lands for medicinal plant cultivation. Phyllanthus amarus plants were grown in the presence of NaCl in order to study the effect of NaCl (80 mM NaCl) in the induction of oxidative stress in terms of lipid peroxidation (TBARS content), H2O2 content, osmolyte concentration, proline(PRO)-metabolizing enzymes, and antioxidant enzyme activities. Groundwater was used for irrigation of control plants. Plants were uprooted randomly on 90 days after sowing (DAS). NaCl-stressed plants showed increased TBARS, H2O2, glycine betaine (GB), and PRO contents, whereas NaCl uptake decreased proline oxidase (PROX) activity and increased gamma-glutamyl kinase (gamma-GK) activity when compared to control. The antioxidant enzymes superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT) were increased under salinity.

Changes in antioxidant potential and sink-organ dry matter with pigment accumulation induced by hexaconazole in Plectranthus forskholii Briq.

An investigation was conducted in Plectranthus forskholii by giving it different concentrations (10, 15, 20, 25, and 30 mg L(-1)) of hexaconazole, a fungicide cum plant-growth regulator, in order to find out its effects on growth, pigment composition, and antioxidant potential. The treatments were given as soil drenching on different growth stages. All the concentrations of hexaconazole used significantly decreased the stem length and leaf area, whereas side branches, fresh and dry matter content, photosynthetic pigments, and antioxidant potential were increased. The number of tubers, length and girth of tubers, fresh and dry weight of tubers and tuber pigments were found to be the highest at a 25 mg L(-1) concentration of hexaconazole. Hexaconazole application at 25 mg L(-1) concentration was found to be more effective than 10, 15, 20, 25, and 30 mg L(-1) in promoting fresh and dry weight of root tuber over 165 days after planting. The pigments like chlorophyll, carotenoid; anthocyanins, xanthophylls and antioxidants such as ascorbic acid, reduced glutathione and total phenol were significantly increased under hexaconazole treatment when compared to untreated control plants.

Changes in carbohydrate metabolism by triazole growth regulators in cassava (Manihot esculenta Crantz); effects on tuber production and quality.

We have evaluated the ability of two triazole growth regulators, viz. triadimefon (TDM) and hexaconazole (HEX), in the enhancement of tuber production and quality in cassava (Manihot esculenta Crantz) through their effects on carbohydrate metabolism. One litre of 20 mg(-1) TDM and 15 mg(-1) HEX solution per plant were used for the treatments and groundwater was given to control plants. Triazole treatments reduced plant height and leaf area, but increased fresh and dry weights. Plants treated with TDM showed an increased net assimilation rate, which is followed by HEX and control plants. Triazole compounds increased the relative growth rate of cassava after 200 DAP, i.e. in the phase of tuber enlargement. Triazole compounds increased the starch and other carbohydrate contents and carbohydrate metabolising enzyme activities. From the results of this study, it can be concluded that these triazoles can significantly enhance the tuber production and quality by affecting the starch metabolism, apart from their fungicidal properties.

Calcium chloride effects on salinity-induced oxidative stress, proline metabolism and indole alkaloid accumulation in Catharanthus roseus.

Catharanthus roseus (L.) G. Don. plants were grown with NaCl and CaCl2 in order to study the effect of CaCl2 on NaCl-induced oxidative stress in terms of lipid peroxidation (TBARS content), H2O2 content, osmolyte concentration, proline (PRO)-metabolizing enzymes, antioxidant enzyme activities, and indole alkaloid accumulation. The plants were treated with solutions of 80 mM NaCl, 80 mM NaCl with 5 mM CaCl2 and 5 mM CaCl2 alone. Groundwater was used for irrigation of control plants. Plants were uprooted randomly on 90 days after sowing (DAS). NaCl-stressed plants showed increased TBARS, H2O2, glycine betaine (GB) and PRO contents, decreased proline oxidase (PROX) activity, and increased gamma-glutamyl kinase (gamma-GK) activity when compared to control. Addition of CaCl2 to NaCl-stressed plants lowered the PRO concentration by increasing the level of PROX and decreasing the gamma-GK activities. Calcium ions increased the GB contents. CaCl2 appears to confer greater osmoprotection by the additive role with NaCl in GB accumulation. The antioxidant enzymes superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT) were increased under salinity and further enhanced due to CaCl2 treatment. The NaCl-with-CaCl2-treated C. roseus plants showed an increase in total indole alkaloid content in shoots and roots when compared to NaCl-treated and untreated plants.

Changes in biochemical constituents and induction of early sprouting by triadimefon treatment in white yam (Dioscorea rotundata Poir.) tubers during storage.

The ability of triadimefon (TDM), a triazolic fungicide, to alter the biochemical constituents and thereby minimizing the days required for sprouting in white yam (Dioscorea rotundata Poir.) tubers during storage under (30+/-2) degrees C in the dark, was studied. TDM at 20 mg/L was given to tubers by dipping the tubers in treatment solution containing 20 mg/L TDM on 10, 25 and 40 d after storage (DAS). Starch, sugars, protein, amino acid contents as well as protease and alpha-amylase activities were estimated on 15, 30 and 45 DAS from two physiological regions viz., apical and basal regions of the tubers. In normal conditions (control) sprouting occurred on 70 to 80 DAS. The starch content decreased, while protein, amino acid, sugar contents and protease and alpha-amylase activities were increased due to TDM treatment and led to early sprouting.