12 • Impacts of Applied Genetics— Micro-Organisms, Plants, and Animals 
information. One new technology— e.g., proto- 
plast fusion, or the artificial fusion of two cells— 
allows breeders to overcome incompatibility 
between plants. But the plant that may result 
still must be selected, regenerated, and eval- 
uated under field conditions to ensure that the 
genetic change is stable and that the attributes 
of the new variety meet commercial require- 
ments. 
In theory, the new technologies will expand 
the capability of breeders to exchange genetic 
information by overcoming natural breeding 
barriers. To date, however, they have not had a 
widespread impact on the agricultural industry. 
As a note of caution, it must be emphasized 
that no plant can possess every desirable trait. 
There will always have to be some tradeoff; 
A young Douglas fir tree propagated 4 years ago (rom a 
small piece of seedling leaf tissue. Three years ago this v.as 
at the test-tube stage seen in the loblolly pine photograph 
often quality for quantity, such as increased 
protein content but decreased yield. 
NEW GENETIC TECHNOLOGIES FOR 
PLANT BREEDING 
The new technologies fall into two categories: 
those involving genetic transformations 
through cell fusion and those involving the in- 
sertion or modification of genetic information 
through the cloning of DNA and its vectors. 
Techniques are available for manipulating 
organs, tissues, cells, or protoplasts in culture; 
for regenerating plants; and for testing the 
genetic basis of novel traits. So far these tech- 
niques are routine only in a few species. 
The approach to exploiting molecular biology 
for plant breeding is similar in some respects to 
the genetic manipulation of micro-organisms. 
However, there is one major conceptual dif- 
Photo Cftdif:- -r'Co 
A plantlet of loblolly pine grown in Weyerhaeuser Co.’s 
tissue culture laboratory. The next step in this procedure 
is to transfer the plantlet from its sterile and humid 
environment to the soil 
