Melatonin and serotonin in flowers and fruits of Datura metel L.

Datura metel is a plant that contains several different neurologically active phytochemicals which affect human health. On-going research has examined the potential role of the human neuroindoles, melatonin and serotonin, in medicinal plants with neurological efficacy. In this report, we describe the quantification of melatonin and serotonin in flowers and developing fruits of Datura metel and the effects of cold stress on the levels of these neuroindoles in the reproductive tissues of this plant. Melatonin and serotonin were found at the highest levels in the least developed flower buds with decreasing concentrations as the flower buds matured. Cold stress significantly increased the concentration of melatonin in young flower buds. In the developing fruit, melatonin was present at relatively stable, high concentrations for the first 10 days after anthesis. After 10-15 days, the ovule had grown to a sufficient size for excision and analysis and melatonin was found to be at the highest concentrations in the developing ovule with minimal concentrations of the neuroindoles in the fleshy fruit. Together, these data indicate that melatonin may play a role in protecting the reproductive tissues during flower and seed formation in a Datura species.

Comparisons of Scutellaria baicalensis, Scutellaria lateriflora and Scutellaria racemosa: genome size, antioxidant potential and phytochemistry.

The genus Scutellaria in the family Lamiaceae has over 350 species, many of which are medicinally active. One species, Scutellaria baicalensis, is one of the most widely prescribed plants in Traditional Chinese Medicine, used for neurological disorders, cancer and inflammatory diseases and has been the subject of detailed scientific study but little is known about the phytochemistry of other Scutellaria. The current study was designed to compare the medicinal phytochemistry of 3 species of Scutellaria used to treat neurological disorders. To accomplish this objective, the specific objectives were (a) to establish an in vitro collection of the South American native; S. racemosa, (b) to botanically characterize S. racemosa and (c) to compare the phytochemistry of S. racemosa with S. baicalensis and S. lateriflora. S. racemosa was established in vitro from wild populations in Florida. Botanically, S. racemosa is diploid with 18 chromosomes, and flow cytometry data indicated that S. baicalensis and S. racemosa have small nuclei with estimated small genomes (377 mbp and 411 mbp respectively). Antioxidant potential studies showed that there were no significant differences in the 3 Scutellaria species. Phytochemical analyses detected and quantified the flavonoids baicalin, baicalein, scutellarin, and wogonin as well as the human neurohormones melatonin and serotonin in leaf and stem tissues from S. baicalensis, S. lateriflora, and S. racemosa. These findings represent the first phytochemical analysis of S. racemosa and establish S. racemosa as a model system for study of medicinal plant secondary metabolism and as a potential source of important phytopharmaceuticals for treatment of human disease.

In vitro conservation and sustained production of breadfruit (Artocarpus altilis, Moraceae): modern technologies for a traditional tropical crop.

Breadfruit (Artocarpus altilis, Moraceae) is a traditionally cultivated, high-energy, high-yield crop, but widespread use of the plant for food is limited by poor quality and poor storage properties of the fruit. A unique field genebank of breadfruit species and cultivars exists at the National Tropical Botanical Garden in the Hawaiian Islands and is an important global resource for conservation and sustainable use of breadfruit. However, this plant collection could be damaged by a random natural disaster such as a hurricane. We have developed a highly efficient in vitro plant propagation system to maintain, conserve, mass propagate, and distribute elite varieties of this important tree species. Mature axillary shoot buds were collected from three different cultivars of breadfruit and proliferated using a cytokinin-supplemented medium. The multiple shoots were maintained as stock cultures and repeatedly used to develop whole plants after root differentiation on a basal or an auxin-containing medium. The plantlets were successfully grown under greenhouse conditions and were reused to initiate additional shoot cultures for sustained production of plants. Flow cytometry was used to determine the nuclear deoxyribonucleic acid content and the ploidy status of the in vitro grown population. The efficacy of the micropropagation protocols developed in this study represents a significant advancement in the conservation and sustained mass propagation of breadfruit germplasm in a controlled environment free from contamination.

Assessment of genetic stability of the germplasm lines of medicinal plant Scutellaria baicalensis Georgi (Huang-qin) in long-term, in vitro maintained cultures.

An approach of combining flow cytometry (FCM) analysis with morphological and chemical profiling was used to assess the genetic stability and bioactive compound diversity in a Scutellaria baicalensis Georgi (Huang-qin) germplasm collection that was clonally maintained in in vitro for a period of over 6 years. Based on the FCM analysis of nuclei samples from young shoots, the nuclear DNA content of S. baicalensis was calculated as 0.84 pg/2C. FCM analysis showed no significant variation in the nuclear DNA contents and ploidy levels in the long-term in vitro maintained germplasm lines. Germplasm lines, acclimatized to ex vitro conditions, exhibited distinctive plant growth and bioactive compound production capacities. The high level of genetic stability observed in in vitro maintained S. baicalensis lines opens up a variety of opportunities such as allowing long-term aseptic preservation and easy distribution of well-characterized germplasm lines of this medicinal plant species. This study represents a novel approach for continuous maintenance, monitoring, and production of medicinal plant tissues with specific chemistry.

Sensitivity of bacterial and fungal plant pathogens to the lytic peptides, MSI-99, magainin II, and cecropin B.

In vitro and leaf disk assays of bacterial and fungal plant pathogens were conducted using three cationic lytic peptides, MSI-99, magainin II (MII), and cecropin B (CB). Growth of bacterial organisms was retarded or completely inhibited by low concentrations of these lytic peptides. The peptides also significantly reduced germination of fungal spores and growth of mycelia; however, higher concentrations of peptides were needed to inhibit fungal growth compared with those needed to inhibit bacteria. The relative efficacy of the peptides depended on the microorganism tested, but CB was the most inhibitory to the majority of the bacteria and fungi assayed. MSI-99, a synthetic derivative of MII with increased positive charge, showed equal or two- to fivefold higher antibacterial activity compared to MII in the in vitro assays. MSI-99 was also superior to MII against the oomycete, Phytophthora infestans but was slightly inferior to MII in assays with the true fungi, Penicillium digitatum and Alternaria solani. In the leaf disk assays, pretreating spores of Alternaria solani and Phytophthora infestans with the peptides at concentrations as low as 10 microg per ml led to significant reductions in the size of early blight lesions and prevented development of any late blight lesions on tomato leaf disks. Our results from in vitro and leaf disk assays suggest that MSI-99 can be used as a transgene to generate tomato lines with enhanced resistance to bacterial and fungal diseases of this crop.