Browsing by Author "Kulkarni, Manoj G."

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Cadmium induces hypodermal periderm formation in the roots of the monocotyledonous medicinal plant Merwilla plumbea.
(Annals of Botany Company., 2010) Lux, Alexander.; Vaculık, Marek.; Martinka, Michal.; Liskova, Desana.; Kulkarni, Manoj G.; Stirk, Wendy Ann.; Van Staden, Johannes.
Background and Aims. Merwilla plumbea is an important African medicinal plant. As the plants grow in soils contaminated with metals from mining activities, the danger of human intoxication exists. An experiment with plants exposed to cadmium (Cd) was performed to investigate the response of M. plumbea to this heavy metal, its uptake and translocation to plant organs and reaction of root tissues. Methods. Plants grown from seeds were cultivated in controlled conditions. Hydroponic cultivation is not suitable for this species as roots do not tolerate aquatic conditions, and additional stress by Cd treatment results in total root growth inhibition and death. After cultivation in perlite the plants exposed to 1 and 5 mg Cd L-1 in half-strength Hoagland’s solution were compared with control plants. Growth parameters were evaluated, Cd content was determined by inductively coupled plasma mass spectroscopy (ICP-MS) and root structure was investigated using various staining procedures, including the fluorescent stain Fluorol yellow 088 to detect suberin deposition in cell walls. Key Results. The plants exposed to Cd were significantly reduced in growth. Most of the Cd taken up by plants after 4 weeks cultivation was retained in roots, and only a small amount was translocated to bulbs and leaves. In reaction to higher Cd concentrations, roots developed a hypodermal periderm close to the root tip. Cells produced by cork cambium impregnate their cell walls by suberin. Conclusions. It is suggested that the hypodermal periderm is developed in young root parts in reaction to Cd toxicity to protect the root from radial uptake of Cd ions. Secondary meristems are usually not present in monocotyledonous species. Another interpretation explaining formation of protective suberized layers as a result of periclinal divisions of the hypodermis is discussed. This process may represent an as yet unknown defence reaction of roots when exposed to elemental stress.
Effect of nutrients and smoke solutions on seed germination and seedling growth of Tropical Soda Apple (Solanum viarum).
(Weed Science Society of America., 2011) Kandari, Laxman S.; Kulkarni, Manoj G.; Van Staden, Johannes.
Solanum viarum, commonly known as tropical soda apple (TSA), is native to Brazil and Argentina but has become a harmful weed in many countries with tropical climates. This study was conducted to reassess the seed biology of TSA found in South Africa. Cold stratification (14 d), acid scarification (20% H2SO4 for 5 min), and sandpaper scarification (30 s) significantly improved percentage germination when compared to the control. The highest germination (99.5%) was achieved when seeds were germinated in 50% Hoagland’s nutrient solution (HS). The lowest germination (66%) was recorded in the absence of phosphorus (P) under alternating light conditions. HS without nitrogen (N) completely inhibited seed germination of TSA under constant light conditions. These findings are useful in controlling TSA by amending the levels of N and P in soils. Seed germination of TSA was significantly enhanced by different concentrations of smoke-water and butenolide solution. Smoke-water dilution of 1:500 v/v and butenolide concentration of 10 -8M showed the highest seedling vigor indices (6,688 and 6,666, respectively) in comparison to the control (1,251) and gibberellic acid (GA3) concentrations (< 5,327). These findings suggest that germination of seeds or seedbanks of TSA might be successfully stimulated using smoke solutions. Subsequently, patches of seedlings emerging after treatment can be mechanically uprooted to reduce the infestation of TSA. However, justifying this with field trials is essential.
The effect of organic biostimulants and the mode of application on the growth and biochemical composition of Amaranthus hybridus L.
(2020) Ngoroyemoto, Nelson.; Van Staden, Johannes.; Finnie, Jeffrey Franklin.; Kulkarni, Manoj G.
Abstract available in PDF.
Pharmacological evaluation of medicinal plants used by Venda people against venereal and related diseases.
(2012) Mulaudzi, Rofhiwa Bridget.; Van Staden, Johannes.; Finnie, Jeffrey Franklin.; Kulkarni, Manoj G.
Venereal diseases (VDs) are infections that are mainly transmitted through sexual intercourse and amongst these are gonorrhoea, syphilis, chlamydia and trichomoniasis. Gonorrhoea is the most commonly known VD and the widest spread contagious infection in the world. Out of 448 million cases of curable venereal infections, gonorrhoea represents 88 million cases and the rest are syphilis, chlamydia and trichomoniasis. Gonorrhoea has recently been rated as in the emergent multidrug resistance phase. Venereal diseases are amongst the major diseases ravaging many rural communities. People infected with these diseases are considered a disgrace in the community. Indigenous populations, for example the Vha-Venda people tend to use medicinal plants to treat these infectious diseases rather than using western medicines. Vha-Venda people have depended on medicinal plants for their health and survival for millenia. In order to validate and give scientific credence to the use of medicinal plants by the Vha-Venda people for venereal diseases, several pharmacological assays were carried out. The study was aimed at evaluating the; antimicrobial, anti-inflammatory activities, HIV-type 1 reverse transcriptase (RT) inhibition properties and to determine phenolic contents as well as evaluating the mutagenic properties of, 12 medicinal plants used by the Vha-Venda people against venereal and related diseases. An attempt was also made toward isolating and identification of the most active compounds from some extracts that were active against Neisseria gonorrhoeae. Twelve medicinal plants and various plant parts, Adansonia digitata (bark), Acacia karroo (bark), Aloe chabaudii (roots), Bolusanthus speciosus (leaves, bark and stem), Ekebergia capensis (leaves and bark), Elephantorrhiza burkei (roots), Grewia occidentalis (roots), Osyris lanceolata (roots), Pappea capensis (leaves), Peltophorum africanum (bark), Pterocarpus angolensis (leaves and bark) and Ximenia caffra (leaves and roots) were evaluated for their antimicrobial properties against two Gram-positive (Bacillus subtilis and Staphylococcus aureus), three Gram-negative (Neisseria gonorrhoeae, Escherichia coli and Klebsiella pneumonia) bacteria and the fungus Candida albicans. The plant materials were extracted with petroleum ether (PE), dichloromethane (DCM), 80% ethanol (EtOH) and water. Methanol was used for extracting materials for phenolic contents and HIV-1RT assays. The Disc diffusion method was used to determine gonococcal percentage inhibition and a microdilution assay was used to determine minimum inhibition concentration (MIC) and minimum fungicidal concentrations (MFC). Bolusanthus speciosus and X. caffra extracts exhibited the best antigonococcal, antifungal and antibacterial activities whilst A. digitata and A. chabaudii showed poor activities. The medicinal plants were also evaluated for cyclooxygenase (COX-1 and -2) and HIV-1 reverse transcriptase inhibition activity. The DCM and PE extracts of A. digitata bark, B. speciosus bark, P. angolensis bark and P. capensis leaves showed good anti-inflammatory activity against both COX-1 and COX-2. Methanol and water extracts of B. speciosus stems, P. africanum bark, P. angolensis leaves and P. capensis leaves exhibited good anti-HIV-1 RT activity. A. chabaudii roots, E. capensis bark and O. lanceolata roots showed low HIV-1 RT percentage inhibition. Phytochemical analysis using spectrophotometric methods revealed the presence of a variety of phenolic compounds in all the plant extracts including total phenolics, flavonoids, gallotannins and condensed tannins. High levels of total phenolics, flavonoids, gallotannins and condensed tannins were detected in X. caffra. Low amounts of flavonoids, gallotannins and condensed tannins were detected in B. speciosus. The Ames test using Salmonella typhimurium tester strain TA98 with and without S9 metabolic activation revealed that all plant extracts were non-mutagenic toward S. typhimurium strains TA98 without metabolic activation. However, E. burkei roots and E. capensis bark showed mutagenic effects toward TA98 after metabolic activation. Therefore, these two plants need to be used with caution, however more studies are required to confirm this result. Good antimicrobial activity observed in X. caffra leaves prompted an attempt to isolate active compounds. A pure compound from X. caffra leaves exhibited moderate activity (63%) against N. gonorrhoeae. However, the structure of the compound has as yet to be ratified. Pharmacological activity of the twelve medicinal plants used by Vha-Venda people against venereal and related diseases were validated in this study. The results obtained in this study give credence to the use of some of these plants. This study has further confirmed the need for screening these medicinal plants for more pharmacological activities. These plants may offer a new source of chemicals for the effective treatment of venereal and related diseases.
Propagation of Romulea species.
(2012) Swart, Pierre Andre.; Van Staden, Johannes.; Kulkarni, Manoj G.; Bairu, Michael Wolday.; Finnie, Jeffrey Franklin.
Romulea is a genus with numerous attractive and endangered species with horticultural potential. This genus in the Iridaceae has its centre of diversity in the winter-rainfall zone of South Africa. This thesis uses ecophysiological and biotechnological techniques to investigate the physiology behind the propagation of some species in this genus. The ecophysiological techniques of soil sampling and analysis and germination physiology were used to determine the natural and ex vitro growth and development requirements of these plants, while biotechnological techniques are used to determine the in vitro growth and development requirements of these plants and to increase the rate of multiplication and development. Soil sampling and analysis revealed that R. monadelpha and R. sabulosa, two of the most attractive species in the genus, grow in nutrient poor 1:1 mixture of clay and sandy loam soil with an N:P:K ratio of 1.000:0.017:0.189 with abundant calcium. To investigate the physical properties of the seeds, imbibition rate, moisture content and viability of seeds were determined. The seed coat and micropylar regions were examined using scanning electron microscopy. To test for suitable stimuli for germination, the effect of temperature and light, cold and warm stratification, acid and sand paper scarification, plant growth promoting substances, deficiency of nitrogen, phosphorous and potassium, and different light spectra (phytochromes) on germination were examined. An initial germination experiment showed germination above 65% for R. diversiformis, R. leipoldtii, R. minutiflora and R. flava seeds placed at 15°C; while seeds of other species placed at 15°C all had germination percentages lower than 30%. More extensive germination experiments revealed that R. diversiformis and R. rosea seed germinate best at 10°C, R. flava seed germinates best when cold stratified (5°C) for 21 days and R. monadelpha germinates best at 15°C in the dark. Seeds of R. diversiformis, R. flava, R. leipoldtii, R. minutiflora, R. monadelpha and R. sabulosa seem to all exhibit non-deep endogenous morphophysiological dormancy while seeds of R. camerooniana and R. rosea appear to have deep endogenous morphophysiological dormancy. The suitability of various explant types and media supplementations for culture initiation was examined for various species of Romulea. Both embryos and seedling hypocotyls can be used for R. flava, R. leipoldtii and R. minutiflora in vitro shoot culture initiation. R. sabulosa shoot cultures can only be initiated by using embryos as explants, because of the lack of seed germination in this species. Shoot cultures of R. diversiformis, R. camerooniana and R. rosea could not be initiated due to the lack of an in vitro explant shooting response. Shoot cultures can be initiated on media supplemented with 2.3 to 23.2 M kinetin for all species that showed an in vitro response. The most suitable concentration depended on the species used. Some cultures appeared embryogenic, but this was shown not to be the case. A medium supplemented with 2.5 M mTR is most suitable for R. sabulosa shoot multiplication. BA caused vitrification of shoots in all the experiments in which it was included and is not a suitable cytokinin for the micropropagation of these species. The effect of various physical and chemical parameters on in vitro corm formation and ex vitro acclimatization and growth was examined. Low temperature significantly increased corm formation in R. minutiflora and R. sabulosa. A two step corm formation protocol involving placing corms at either 10 or 20°C for a few months and then transferring these cultures to 15°C should be used for R. sabulosa. When paclobutrazol and ABA were added to the medium on which R. minutiflora shoots were placed, the shoots developed corms at 25°C. This temperature totally inhibits corm formation when these growth retardants are not present. BA inhibited corm formation in R. leipoldtii. Corms can be commercialized as propagation units for winter-rainfall areas with minimum temperatures below 5°C during winter. Although an incident of in vitro flowering was observed during these experiments, these results could not be repeated. Although none of the corms or plantlets planted ex vitro in the greenhouse survived, a small viability and an ex vitro acclimatization experiment shows that the corms produced in vitro are viable. One embryo of the attractive R. sabulosa, produces 2.1 ± 0.7 SE shoots after 2 months; subsequently placing these shoots on a medium supplemented with 2.5 μM mTR for a further 2 months multiplies this value by 5.5 ± 1.3 SE. Each of these shoots can then be induced to produce a corm after 6 months. This means that 1 embryo can produce about 12 corms after 10 months or about 65 corms after 12 months (if shoots are subcultured to medium supplemented with 2.5 μM mTR for another 2 months). Embryo rescue can enable wider crosses within this genus. These results can be used for further horticultural development of species in this genus and their hybrids and variants.