Ch.8— The Application of Genetics to Plants • 147 
Figure 28.— The Process of Plant Regeneration From Single Cells in Culture 
Desired plant 
Leaf 
Virus-free 
Field performance tests 
Cell multiplication 
Cell wall 
removal 
Tissue 
Exposure to 
selection pressure 
e g., high salt 
concentration 
Roots and 
shoots 
Surviving cells 
go on to form callus 
-*■ Root-promoting 
hormones 
The process of plant propagation from single cells in culture can produce plants with selected characteristics. These selec- 
tions must be tested in the field to evaluate their performance. 
SOURCE: Office of Technology Assessment. 
Photo credit: Plant Resources Institute 
Multiplying shoots of jojoba plant in tissue culture on a 
petri dish. These plants may potentially be selected for 
higher oil content 
culture because of the increased speed with 
sources of impro\ed seed or cutting material. 
(See table 26.) In some cases, producing plants 
bv other means is simply not economically com- 
petitive. A classic example is the Boston fern, 
which, while it is easy to propagate from runner 
tips, is commercially propagated through tissue 
which it multiplies and the reduced costs of 
stock plant maintenance. A tissue culture stock 
of only 2 square feet (ft^) can produce 20,000 
plants per month.’® 
Currently, mass production of such cultivars 
as strawberries (see Tech. Note 9, p. 163.), 
asparagus, oil palms, and pineapples is being 
carried out through plant tissue cultures.” Very 
recently, alfalfa was propagated in the same 
wav, giv'ing rise to over 200,000 plants, several 
thousand of w'hich are currently being tested in 
field trials. Also, 1,300 oil palms, selected for 
high yield and disease resistance, are being 
tested*^ in Malaysia. Other crops not produced 
by this method but for which cell culture is an 
important source of breeding variation include 
'“D. P. Holdgate, “Propagation of Ornamentals by Tissue Cul- 
ture," in Plant Cell, Tissue, and Organ Culture, J. Feinert and Y. P. S. 
Bajaj (eds.) (New York: Springer-V'erlag, 1977). 
"T. Murashige, "Current Status of Plant Cell and Organ Cul- 
tures," HorfScience 12(2):127, 1977. 
'^“The Second Green Revolution,” special report, Business Week, 
Aug. 25, 1980. 
