How did the coconut lead to tissue culture?
By Chelsie Vandaveer
November 22, 2001
killerPlants Tendrils: ~~1~~2~~3~~4~~5~~
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The coconut palm (Cocos nucifera) is monotypic, a single species within its genus. It produces a fruit called a drupe similar to a cherry or olive. But unlike the cherry or olive, the coconut's outer portion is modified into a fibrous flotation device and the seed is eaten. Within the seed is a liquid endosperm that led to scientific discovery and launched an industry.
Gottlieb Haberlandt was an Austrian botanist teaching at the University in Graz. In 1902, Haberlandt published his hypothesis of the totipotency of plant cells; each cell having the potential to develop into an entire plant. Some ideas are ahead of their time.
In 1941, Johannes van Overbeek was studying the development of plant embryos and tissues. Pieces of plants survived for a while in a nutrient-filled test tube, then dwindled away. But when he added coconut milk to the nutrient solution, the plant cells began dividing and growing at an accelerated rate.
F.C. Stewart took pieces (explants) of phloem from carrot root and placed them into a rotating flask of nutrients with coconut milk. The carrot cells divided and differentiated--some of the cells grew into small roots. Left in the swirling nutrient media, the carrot explants ceased to grow, but removed and placed on agar, some of the explants developed green shoots. When these were planted into soil, the carrots leafed, flowered, and produced seed.
In the 1950s, the growth factor in coconut milk could be purified, but not isolated. The factor was not identified until Folke Skoog and Carlos Miller discovered adenine, one of the breakdown products of DNA. The growth factor belonged to a family of chemicals related to adenine, named the cytokinins because they stimulate cytokinesis (cell division).
The discovery of plant hormones led to the tissue culture industry which has revolutionized horticulture and agriculture. Tissue culture (TC) has affected almost everyone whether they garden or not. Crop diseases are often transferred through seeds or cuttings, TC plants are free of disease which has kept the price of food down. TC plants are genetically identical to the parent plant; the average person can now own unique hybrids and rare plants. Because TC plants are inexpensive and have a high survival rate, it helps keep plant poachers out of nature preserves.
The University of New England, Australia, Horticultural Science Group has an introduction to tissue culture for home gardeners. To learn more about tissue culture, click on the link:
http://www.une.edu.au/~agronomy/AgSSrHortTCinfo.html
killerPlants Tendrils: ~~1~~2~~3~~4~~5~~
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