156 • Impacts of Applied Genetics— Micro-Organisms, Piants, and Animais 
portant food plants indigenous to the continen- 
tal United States are limited to the sunflower, 
cranberry, blueberry, strawberry, and pecan. 
The centers of genetic diversity, found mostly in 
tropical latitudes around the world, are be- 
lieved to be the areas where progenitors of ma- 
jor crop plants originated. Today, they contain 
genetic diversity that can be used for plant im- 
provement. 
It is difficult to estimate the financial return 
from the germplasm that has been collected, 
but its impact on the breeding system has been 
substantial. A wild melon collected in India, for 
instance, was the source of resistance to pow- 
dery mildew and prevented the destruction of 
California melons. A seemingly useless wheat 
strain from Turkey— thin-stalked, highly sus- 
ceptible to red rust, and with poor milling prop- 
erties— was the source of genetic resistance to 
stripe rust when it became a problem in the 
Pacific Northwest. Similarly, a Peruvian species 
contributed "ripe rot” resistance to American 
pepper plants, while a Korean cucumber strain 
provided high-yield production of hybrid cu- 
cumber seed for U.S. farmers. And a gene for 
resistance to Northern corn blight transferred 
to Corn Belt hybrids has resulted in an esti- 
mated savings of 30 to 50 bushels (bu) per acre, 
with a seasonal value in excess of $200 million.^® 
(See table 28.) 
The effort to store and evaluate this collected 
germplasm was promoted by the Agricultural 
Marketing Act of 1946, which authorized re- 
gional and interregional plant introduction sta- 
tions (National Seed Storage Centers) run coop- 
eratively by both Federal and State Govern- 
ments. The federally controlled National Seed 
Storage Laboratory in Fort Collins, Colo., was 
established in 1958 to provide permanent stor- 
age for seed. In the 1970’s, it was recognized 
that the system should include clonal material 
for vegetatively propagated crops, which can- 
not be stored as seed. Although their storage re- 
quires more space than comparable seed stor- 
^“U.S. Department of Agriculture, Agricultural Research Serv- 
ice, Introduction, Classification, Maintenance, Evaluation, and Docu- 
mentation of Plant Germplasm, (ARS) National Research Program 
No. 20160 (Washington, D.C., U.S. Government Printing Office, 
1976). 
Table 28.— Estimated Economic Rates of Return 
From Germplasm Accessions 
1. A plant introduction of wheat from Turkey was found to 
have resistance to ali known races of common and 
dwarf bunts, resistance to stripe rust and flag smut, 
plus field resistance to powdery and snow mold. It has 
contributed to many commercial varieties, with 
estimated annual benefits of $50 million. 
2. The highly successful variety of short-strawed wheat, 
‘Gaines’ has in its lineage three plant introductions that 
contributed to the genes for the short stature and for 
resistance to several diseases. During the 3 years, 
1964-66, about 60 percent of the wheat grown in the 
State of Washington was with the variety ‘Gaines’. In- 
creased production with this variety averaged slightly 
over 13 million bu or $17.5 million per year in the 3-year 
period. 
3. Two soybean introductions from Nanking and China 
were used for large-scale production, because they are 
well-adapted to a wide range of soil conditions. All ma- 
jor soybean varieties now grown in t e Southern United 
States contain genes from one or both of these in- 
troductions. Farm gate value of soybean crop in the 
South exceeded $2 billion in 1974. 
4. Two varieties of white, seedless grapes resulted from 
crosses of two plant introductions. These varieties 
ripen 2 weeks ahead of ‘Thompson Seedless’. Benefits 
to the California grape industry estimated to be more 
than $5 million annually. 
SOURCE: U S. Department of Agriculture, Agricultural Research Service. In- 
troduction, Classilicatlon, Maintenance. Evaluation, and Docu- 
mentation ol Plant Germplasm, (ARS) National Research Program No 
20160 (Washington, D C., U.S. Government Printing 0(flce,1976) 
age, 12 new repositories for fruit and not crops 
as well as for other important crops, from hops 
to mint, were proposed by the National (ierm- 
plasm Committee as additions to the National 
Germplasm System (see lech. Note 12, p. 163). 
(The development of tissue culture storage 
methods may reduce storage costs for thest> 
proposed repositories.) 
The National Germplasm System is a \ ital link 
in ensuring that germiilasm now ivxisting will 
still be available in the futurt'. Ilowmt'i', the 
present system was challenged after the Soutli- 
ern corn blight epidemic of 1970. Many scien- 
tists questioned whether it was large enough 
and broad enough in its pi'csent lorm to pio\ ide 
the genetic resources that might he needed. 
The devastating effects of the corn blight ol 
1970 actually led to the coining of the term cro[) 
vulnerability. During the e|)idemic, as much as 
15 percent of the entire \ield was lost. Sunn* 
fields lost their whole crop, and entiic sections 
of some Southern States lost 50 pt'rcent ol their 
