The Production and Function of Mucilage by Sweet Basil (Ocimum basilicum L.) Seeds.

Sweet basil (Ocimum basilicum L.) seeds are myxospermic, producing a thick layer of mucilage around the testa within minutes after hydration. The mucilage and seeds are bottled as a popular drink in many Asian countries. Myxospermy is most prevalent among plant species adapted to surviving in arid sandy soils, though its significance in determining the ecological fitness is unclear. The mucilage produced by myxospermic seeds is reported to be composed of cell-wall polysaccharides that are deposited during development of testa cells. In this study, sweet basil seeds were examined using light and environmental scanning electron microscopy. The mucilage of basil seeds it held together by columnar structures that unfolded from the testa and helped hold and stabilize the mucilage to the seed surface. The mucilage was removed using diluted hydrochloric acid to compare performance of seeds with and without mucilage. Mucilage removal did not inhibit seed germination in a laboratory under ideal conditions, but did change the water content of seeds a lot. Mucilage enabled seeds cling to an incline board set to a steeper angle than that of dry seeds. Soil (media) test showed no significant difference between seeds with and without mucilage.