and scarcely 100 years of scientific plant breeding, helps fight epidemics of pests and pathogens that threaten the security of the global food supply.
by Linda McCandless
Geneva, NY - The germplasm repository at Cornell's experiment station in Geneva, N.Y., contains the world's largest collection of apple and grape varieties - some ancient, some from far reaches, some highly cultivated, and some utterly wild. Together, they are protection against diseases and insects that threaten these crops now and in the future.
To preserve the diversity of the plant gene pool, botanists have trekked into scarcely inhabited interiors on every continent in search of the wild relatives of the world's important agricultural crops. Prospecting for crop germplasm is like prospecting for a kind of green gold. Germplasm contains important genetic traits that have the potential to boost insect and disease resistance, increase yield, and improve quality. Germplasm, the product of millions of years of evolution and scarcely 100 years of scientific plant breeding, helps fight epidemics of pests and pathogens that threaten the security of the global food supply.
"Germplasm is an insurance policy for the future," says Robert A. Pool, professor of horticultural sciences and viticulture at the Agricultural Experiment Station at Geneva. The collection of apple and grape germplasm maintained by the Plant Genetic Resources Unit (PGRU) is among the most extensive and diverse in the world and Pool is one of many station researchers who actively use the collection. The repository is a component of the National Plant Germplasm System administered by the Agricultural Research Service, the principal research arm of the U.S. Department of Agriculture.
"Our mission is to acquire, maintain, characterize, document, and distribute plant germplasm for certain seed-propagated crops as well as apple, cold-hardy grape, and tart cherry," says Jim McFerson, director of the PGRU. Germplasm is the hereditary material, or DNA, of living organisms. In many crops, germplasm is contained in seed; in others, like apple, grape, and cherry, which can be clonally propagated, germplasm is contained in budwood, as well as in seed.
The PGRU staff cooperates with other scientists nationally and internationally to make sure the genetic resources of PGRU's crops are conserved and utilized in breeding and other research programs. "If there is no cooperation, genetic resources are not characterized or used and then they are not beneficial to breeders, growers, and consumers," McFerson points out. Of particular importance to the PGRU are collaborative efforts pursued with Cornell University scientists on site at the experiment stations in Geneva and in Ithaca.
The apple and grape collection at Geneva was started in 
1880 when the station was established by the New York state legislature. By 1900, the collection included more than 700 varieties of apples and crab apples. Today, there are more than 3,000 accessions of apple and more than 1,300 accessions of cold-hardy grapes. An accession is a sample that represents genetically unique material. Other important holdings at Geneva include buckwheat, celery, vegetable cole crops (broccoli, cabbage, cauliflower, etc.), onion, petunia, winter squash, and tomato. The clonal crops collections have been under the auspices of PGRU since 1982, when researchers and administrators at Cornell pushed to have the clonal repository located in Geneva. Cornell owns the acreage; the USDA owns the building and holds a long-term lease from Cornell. The PGRU also leases over 85 acres and Cornell supplies additional lab, office, and greenhouse space.
The clonal repository of apples and grapes in Geneva is one of Cornell's most unique "libraries." It is alive, it is green, and most of it is housed outdoors on a 50-acre farm. Like the original ark of diversity, it is planted two by two.
The apple collection, curated by Phil Forsline, consists of some 5,000 apple trees representing 2,500 different accessions. Among them are wild species, landraces, current cultivars, and obsolete cultivars. The grape collection, curated by Warren Lamboy, comprises 2,600 plants, or two each of 1,300 different accessions. It contains cold-hardy wine grapes, table grapes, French-American hybrids, wild species, and rootstocks. Detailed records of each specimen are maintained on a local and national computer database. Each year, about 3,000 apple and grape accessions are distributed as budwood or seeds to researchers worldwide. The tart cherry collection, recently initiated, has been propagated and is being held in PGRU screenhouses for virus screening before field planting in 1997.
In both apples and grapes, PGRU has recently expanded
its efforts to systematically characterize the entire collection for several horticultural traits. With help from station researchers like Herb Aldwinckle, Roger Way, and Bob Lamb, Forsline has established an "apple core subset" of 200 accessions. Forsline selected this subset to represent the maximum genetic diversity by a minimum number of accessions. It includes familiar cultivars as well as diverse wild species. A replicated field planting coordinated by Terence Robinson was established in 1994 and will soon be available for detailed investigation.
"Some of our collection dates back to ancient Rome, some of it is important cultivated varieties, and some of it comes from Asia," Forsline says. Researchers think Central Asia is the center of origin of apple and that, in general, the species migrated along trade, silk, and spice routes into the Middle East and then Western Europe, making adaptations all along the way. Wild apples in Asia range up to a full pound in weight; in color from white to yellow, green, and red; in taste from sweet to bitter; in flowers from five-petals to multi petals to no petals at all; and in tree form from single to multi-trunked to bushes. Some apples are hardy in -40°C winters; some have adapted to deserts or salty, windswept cliffs.
Forsline is a mild-mannered man who, with gun-toting guides to ward off bears, braves rugged, mountainous terrains to stalk wild apples. Explorations this fall took him and an international team of researchers to Kazakhstan in central Asia in search of Malus sieversii , which is a wild relative of the cultivated apple (M. x domestica ). Herb Aldwinckle, who had helped initiate the apple exploration project on a trip to Asia in 1989, found and brought back M. sieversii germplasm. Since then, Forsline and Aldwinckle have been collaborating to evaluate M. sieversii for resistance to apple scab, cedar apple rust, and fireblight - all important diseases affecting commercial apple orchards in New York State.
On this last trip, Forsline used Norm Weeden's and Warren Lamboy's analysis of isozyme variation in the previously collected materials to map out regions of Kazakhstan where genetic diversity would most likely occur. And it worked! Forsline found large, high quality M. sieversii unlike any he had ever seen before. He brought back seeds and cuttings from 46 different trees. "This wild germplasm is critical in maintaining diversity in the gene pool," Forsline explains. If a new strain of insect or disease comes along that decimates current commercial varieties of McIntosh or Golden Delicious, for instance, germplasm which has evolved desirable traits through natural selection might provide genes for resistance that could be bred into future varieties.
Cornell's living library is on the brink of drastic change. Using a technique called cyropreservation, PGRU has begun to preserve 
apples in tanks of liquid nitrogen rather than whole trees in orchards. Apple germplasm is "frozen" for future use, held as live 3.5 cm budwood pieces in five lots of 12 buds each, in airtight tubes, at -170°C in the vapor phase section of a liquid nitrogen tank.
It takes $75 to $100 a year to maintain one tree in the PGRU orchard. In addition to space, a lot of labor is involved in spraying, cultivating, pruning, and monitoring the accessions, which are often unadapted germplasm. In addition, it is costly to distribute 3,000 accessions annually to users as scion wood. In liquid nitrogen tanks, the economics are much better ($1 per tree per year) and the collection is safe from the constant threat of weather, insects, and pathogens. As long as germplasm requesters follow suggested grafting procedures, propagating the cryopreserved buds poses no problems, according to Bill Srmack, PGRU technician. Because each tank can preserve 660 accessions, the PGRU could conceivably replace up to five acres worth of orchard with just one liquid nitrogen tank. And, the entire collection of 2500 accessions will be backed up in cryopreservation at the USDA-ARS lab in Ft. Collins.
Scientists working with germplasm may seem like unlikely heroes. Following the likes of Benjamin Franklin, Thomas Jefferson, and Nikoli Vavilov, who collected seeds and cuttings to improve the economic return from farming, they represent the front lines in the fight to preserve future generations of important agricultural crops. Their tools range from the simplest hand-held knife to the most advanced molecular techniques.
USDA-ARS germplasm collection for other crops are held across the country, often in cooperation with land-grant universities like Cornell. Other gene banks exist around the world, but many of these international germplasm collections are increasingly subject o political, economic, and social upheaval. During the siege of Leningrad in 1941-1942, thousands of people died of starvation, including 10 scientists who worked at the N. I. Vavilov Botanical Institute. The Vavilov gene bank contained seeds from more than 187,000 specimens of plants collected from around the world. Peanut specialist Alexander Stchukin and rice expert Dmitri Ivanov were among the scientists who starved to death while preserving this mountain of rice, potatoes, peanuts, and other edibles.
Curators in the 1990s have not been driven to such drastic measures, but the level of commitment and dedication remains the same. "The challenges are very real," says McFerson. The most important battles facing the today's curators of the world's supply of germplasm include displacement of traditional agricultural systems and loss of landraces, environmental degradation of important wild habitats, and dwindling financial resources with which to maintain and augment the current collections. "We'll need even more and better cooperation to meet them," says McFerson, "but I am extremely confident that we will."
This story originially appeared inFocus magazine, a publication of the New York State Agricultural Experiment Station at Geneva, the Cornell University Agricultural Experiment Station at Ithaca, and the College of Agriculture and Life Sciences, a statutory college of the State University of New York, at Cornell University, Ithaca, NY. Vol. 5, No.1
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