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  • Author or Editor: Matthew Cousins x
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Geophytes store carbohydrates in modified underground shoot systems protected by a broad array of biologically active chemistry. In vitro formation of storage organs requires months in the lab instead of years in the field, when water and nutrients are correctly supplied. Liquid and agar systems in large and small vessels were compared for sugar and water use with turmeric (Curcuma longa) as a model plant. Small jars on a shaker were compared with large, flat-bottomed vessels containing thin films of liquid media, intermittently tilted at slight inclines that allow the advantages of liquid phase transfer with gentle agitation. Liquid culture in small vessels on a shaker yielded the most plants and liquid culture on a thin-film rocker in a large vessel yielded the largest plants. Increased and improved biomass (fresh and dry) in liquid culture compared to agar was based on greater sugar use. When large vessels of liquid media were grown for 5 and 6 months on a rocker, 400 mL of media yielded 150 to 200 g (fresh weight) of plants. Similarly, 13 to 16 g (dry weight) of plant tissue was derived from 24 g of sugar. Plants were about one-third rhizome by fresh mass. Rhizomes had greater dry and fresh weight than leaves or roots, indicating solute actively accumulated in the rhizome. The rhizomes had normal morphology, characteristic pigments and fragrance, and rhizome extracts had strong antioxidant potential. The gentle rocking action of plantlets in sugar-containing liquid medium was demonstrated to produce functional storage organs.

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Beach Vitex (Vitex rotundifolia Lf.) was introduced to coastal Carolina areas in the 1980s. Since its introduction, it has become a major invasive plant problem. Beach Vitex rapidly dominates the vegetation and eliminates many native plant species on primary and secondary coastal dunes. It grows rapidly and reproduces vegetatively by rooting at the nodes. Thousands of fruits, containing one to four seeds each, are produced annually and assist in the plant's spread. Beach sand in areas dominated by Beach Vitex was found to possess hydrophobic qualities, while sand collected from areas not populated by Beach Vitex readily allowed water infiltration. GC-MS analysis of hydrophobic sand extracts showed four peaks that were absent from extracts of non-hydrophobic sand. These peaks were also present in chromatograms of water extracts of Beach Vitex fruits and leaves. Comparison of GC-MS spectra with compounds previously identified in Beach Vitex indicated that one compound was a diterpene (likely ferruginol or abietatrien-3ß-ol). The second compound is likely a flavonoid (possibly casticin, artemetin, or vitexicarpin). Two additional compounds are present at low levels and are possibly phenylnaphthalene compounds. These four compounds appear to be synthesized and incorporated into surface tissues of Beach Vitex leaves and fruits and are transferred to sand during rain events and decomposition. Further studies of Beach Vitex plant parts and beach sands are being conducted to further elucidate the possibility that these chemicals are involved in the intriguing property of sand hydrophobicity. This property may aide Beach Vitex in its competition with plants possessing less expansive root systems.

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