Every gardener should keep up with what's going on in tissue culture

Flower & Garden Magazine, Feb-March, 1985 by Herb Saltford

Although as early as 1902, tissue culture was mentioned and described by a German scientist, little came of it until the 1950's when California growers put it to commercial use with orchids.

Now, quickly sprouted since 1976, tissue culture techniques are producing various kinds of plants by the millions instead of one by one.

In vitro is another name for the method. In Latin this means "under glass." Some call it "micropropagation." Yet another term used is "meristem culture." As it is performed primarily in test tubes or something similar, tissue culture requires very little space or capital, compared to other plant propagation methods, and it assures pest- and disease-free plants as a result.

Handled under sterile conditions, tiny tips or other parts of plants, placed separately in small glass vessels containing a nutrient gelatin medium, are self-generating and produce new plantlets. Subsequently moved to larger jars, these grow fast under ideal light and temperature suuroundings, eventually graduating to greenhouses and gardens.

Tissue culture makes an exact duplicate or clone of each original. It hastens the creation of large numbers of healthy plants, uniform in color, size, appearance, and every other way. Consequently, as John Walters observes at his Zeeland, Michigan, laboratory, "This rapid and proven means of growing disease-free, predictable plants has all the indications of becoming the major source of plant production for the nursery business."

Whether this will prove to be our century's greatest horticultural innovation, only time can tell, but it certainly should rank high on the list. What it will mean to the ordinary gardener remains to be seen, although we are beginning to see indications.

From McMaster University, for example, comes word of a plant hormone formulation that, when applied to a dormant spike of Phalaenopsis orchid, will induce formation of a meristematic duplicate right on the plant. Accordingly, gardeners can enjoy the benefits of producing duplicates called Keikis (Hawaiian for babies) without expense of a sophisticated laboratory. Keikigrow formulation is available from Plant Hormones, Box 345, McMaster University, Hamilton, Ont., Canada L8S 100.

Keikigrow presents further promise with other kinds of orchids, as well as philodendrons, ferns and certain hard to reproduce species such as carnivorous Nepenthes (pitcher plants). As the product provides endless possibilities for experiment, its developers hope to hear of growers' results.

Other researchers are working with meristem propagation to make scarce Hosta varieties more readily available to gardeners. Until recently, crown division was the only means of increase, taking too much time for introduction of any newly developed plants.

Scientists who took meristematic buds, or "eyes," from the rhizome of Hosta decorata had good luck in propagating, but found that the method reduced the specimen's growth potential, and that tissue taken from under the soil presented contamination problems.

At University of Illinois, workers were successful in propagating from hosta flowers taken at a specific stage of development. The flower scapes had to be allowed to develop until florets were separated and had reached a length of between 1/2 and 1 centimeter. Tissue taken from larger florets or more mature scapes was not successful. Ohio State University workers report propagating daylilies from tissues taken from immature flower buds.

Since the initial rush in the late 1970's, after the University of California's Dr. Toshio Murashige pioneered tissue culture with special courses at the Lake Placid, New York, W. Alton Jones Cell Science Center, competition has thinned the crop of companies participating in the then new technique. In Florida the original 27 laboratories have diminished to six.

In the meantime, Hollywood's Oglesby Nursery has grown five-fold.

Specialties there are spathiphyllum, Gerbera, daylily, schefflera, blueberry, rhododendron, and rose. Said to be the most sophisticated laboratory of its kind in the U. S., Oglesby has improved bananas, avocados, and mangos, with 95 per cent of its production devoted to material for growers. It also exports to Africa, Australia, Philippines and Japan. More than three million plants are produced there annually on a round the clock schedule.

From West Grove, Pa., where the Conard-Pyle Company wholesales its Star Roses and other nursery stock, we learned that their tissue cultured rhododendrons from Olympia, Washington's Briggs Nursery, Inc., have outgrown cutting propagated plants of the same varieties.

The list of tissue cultured species keeps on growing as researchers conquer problems, while raising hope for other woody plants.

The U. S. Department of Agriculture at Beltsville, Md., has successfully multiplied apple, blueberry, and blackberry shoots. By one estimate, a single blackberry tip could yield 2-1/2 million tissue particles ready for rooting in 28 weeks.

When scientists at the state agricultural station in Geneva, N.Y., discovered air pollution damaging vineyards, they used tissue culture to create pollution resistant types.