INTRODUCTION TO PLANT BREEDING

AGRONOMY 815 / COURSE NOTES

P. STEPHEN BAENZIGER, 338 Keim Hall, 472-1538

DEPARTMENT OF AGRONOMY / UNIVERSITY OF NEBRASKA

PLANT INTRODUCTIONS

Fehr,. Chapt. 11
Poehlman, Chapt.7
Briggs & Knowles, Chapt.3
Allard, Chapt. 3
See also Crops and Man p. 149-167.

Vavilov's Centers of Diversity, initially proposed as centers of origin, were designated as either primary (domestication) or secondary (further selection) centers. Harlan and Anderson questioned the association of centers of diversity with centers of origin and suggested that regions where greatest variation existed were more likely to be centers of recombination rather than origin. Regardless of their 'origin' these centers of diversity are very important to plant breeders in providing valuable germplasm. Some of the Centers are: Near East (small grains, pulses), Africa (sorghum, millets), China (rice, soybeans), Southeast Asia (rice, millets), and Mesoamerica (corn, potatoes).

NOTE THAT THE PROPAGULE WILL VARY WITH THE CROP/PLANT (MAYBE SEEDS, CUTTINGS, TISSUE CULTURES, POLLEN GRAINS, ETC.).

With movement of plant species by man (nomads, early explorers, early settlers), two important observations became apparent from the early plant introductions.

1. There should be a similarity in climate between the region of origin and the new area of production. Ecogeographical similarity for similar adaptation zones. e.g., Turkey wheat, brought to Kansas from Russia. Alfalfa brought into New England (from England called lucerne) and Mexico -- most successful when brought into Mexico (from Spain called alfalfa).



2. An introduced crop was most successful if it possessed a considerable amount of variation for adaptation traits -- allows some selection in the new area, e.g., landraces, populations.

PLANT INTRODUCTION IN THE U.S.: A model for most collections.

• COMMENT ON THE NATIVE GENETIC RESOURCES OF THE U.S.



• COMMENT ON OUR AGRICULTURAL PRODUCTIVITY BASED UPON OUR "CROPS".
  

Early immigrants always brought their animals and plants. Also worked with indigenous people to use new crops.

1819 . . . American Foreign Officers were instructed to collect seeds and plants of potential value.

1839 . . . Appropriations from Congress for collection and distribution of seeds.

1898 . . . Office of Foreign Seed and Plant Introductions established in the U.S.D.A.

• COMMENT ON THE LIFE OF MARK CARLETON -- EARLY PLANT EXPLORER WHO INTRODUCED KHARKOV WINTER WHEAT AND BROUGHT THE DURUM WHEATS TO AMERICA. FIRST PRESIDENT OF THE ASA. DIED IN THE MOUNTAINS OF PERU EXPLORING FOR HIGH FROST TOLERANT PLANTS. Also mention only one durum wheat named after him due to his scandal. Note varieties are named after people normally only after they have died -- must be careful to develop a variety that will be worthy of the person that it is to be named in honor of.

1946 . . . Research and Marketing Act. Regional research funds were available for the establishment of Regional Plant Introduction Stations. The first being established at Ames, Iowa in 1948 to serve the North Central Region. Other collections are at Pullman, WA, Geneva, NY, Griffin, GA, and Glendale, MD.

1956 . . . Appropriation of funds through an act of Congress for the construction of a National Seed Storage Laboratory at Fort Collins, Colorado, to help preserve germplasm, both introduced and domestic. Working vs. Core vs. Base Collection.

Plant Quarantine and Plant Introduction

Introduced material usually goes to the Plant Inspection Station, Washington D.C. where it is inspected for diseases, insects, fumigated if necessary, assigned a P.I. number, documented and sent to the regional station having priority for the crop or to the individual requesting it. It is extremely important that quarantine regulations are met. Karnal bunt on wheat was recently introduced into Mexico from India. Stripe rust on wheat was recently introduced into Australia from Europe. Other example include the Mediterranean Fruit Fly, Russian Grain Aphid, and coffee rust. Transport of seed within a country can also cause severe problems. Cephalosporium stripe was brought to Nebraska with a shipment of Pacific Northwest wheat to a grower. HENCE THERE CAN BE QUARANTINES BETWEEN COUNTRIES AND WITHIN COUNTRIES -- CALIFORNIA AND FLORIDA OFTEN WILL NOT EXCHANGE FRUIT PRODUCE DUE TO POSSIBILITY OF INTRODUCING NEW INSECTS/DISEASES.

• Requesting materials already introduced.

Contact the appropriate regional introduction station where working collections are maintained.

• Requesting acquisition of new P.I.'s.

Requests are channeled via the regional stations to the ARS Germplasm Resources Laboratory, Plant Genetics and Germplasm Institute, Beltsville, Md.

• Regional Plant Introduction Stations -- maintain working collections.



Northeast Region . . . . . . . . . . . . . .Geneva, New York


Southern Region . . . . . . . . . . . . . . .Experiment, Georgia


North Central Region . . . . . . . . . . . Ames, Iowa


Western Region . . . . . . . . . . . . . . . Pullman, Washington


(Also, for special crops . . . potatoes -- Sturgeon Bay, Wisconsin; bamboo -- Savannah, Georgia; tropical plants -- Coconut Grove, Florida.)

• Functions of regional stations:



1. Determine germplasm needs within the region;
   
   
2. Assist with foreign explorations to fill regional needs;



3. Multiply, evaluate and maintain new plant and seed collections of crops adapted to the region with minimum loss of genetic variability within the strains.;



4. Distribute the seed and plant accessions to scientists.




Each item received is given a plant introduction (PI) number by which it is subsequently identified. Catalogs of available accessions are published by each regional plant introduction station.

1. National Seed Storage Laboratory, Fort Collins, Colorado.




Long term storage of seeds. This is the base collection for all crops. Samples are distributed from the National Seed Storage Laboratory only after other sources are exhausted. It is the equivalent of the National Archives.

Storage at 4 -- 5^o C and 32% RH . . . most seeds remain viable for 10 -- 20 years. Before viability is lost, seed stocks are renewed. Chambers that can be cooled to -12^o C are also available for research into even longer term storage. Currently are working on storing seeds in liquid nitrogen.

Major collections include -- wheat, oats, barley, maize, potatoes, sorghum, soybeans, flax, rice, cotton, tobacco and other widely cultivated crops.

Seed stocks of obsolete varieties are stored and maintained as well as new varieties as they are released. Classical genetic stocks for research are also stored. However, access to most genetics stocks collections is through a genetics stocks curator who is often outside the National Plant Germplasm System because he has unique skills required to accurately maintain the genetic stocks which often not present within USDA.

Ref. Frankel, O. H. and J.G. Hawkes (eds.) Crop Genetic Resources for Today and Tomorrow.

1974 . . . Establishment of the International Board for Plant Genetic Resources (IBPGR) -- FAO, Rome.

1. Overview of world-wide state of genetic resource conservation.



2. Promote and coordinate efforts to conserve germplasm of the major field crops.



3. Assist appropriate institutions in extending their capabilities for storing and evaluating germplasm collections (IBPGR -- often are facilitators rather than having active collections. Problem is that by relying upon national programs, the collections can be forgotten in times of national crises -- some of the maize collections in Central America have been injured during economic slumps).

World Collections being assembled at International Research Centers:

Note: there is considerable concern that the developed countries are trying to abuse less developed countries' germplasm resources by the international collections. Hence, many countries have very restriction germplasm exchange programs (past example was China and soybeans). Politics has also limited germplasm exchange (for example -- United States and the Soviet Union during the cold war).

The driving force for introductions is Vavilov's extension of Welsh's LAW OF HOMOLOGOUS SERIES:

Welsh stated: "If any character is variable in one species of a given group, there will appear a tendency to variation also in another related species: and if any character is entirely constant in one species of a given group, it will tend to be constant in related species." THIS LAW IS THE REASON FOR OPTIMISM OF MANY GERMPLASM SEARCHES.

Note that the center of diversity of crop species is also often the center of diversity for the parasites that attack the crop. Hence there is a co-evolution of the species and the parasites. Note also that the center of diversity for one trait may be different from the center of diversity for other traits (e.g., Israel, Syria, Jordan are the center of diversity for wheat, but Ethiopia is the center of diversity for Barley yellow dwarf virus in wheat, barley, etc.). THIS ALSO MEANS THAT IF A PLANT IS TAKEN FROM ITS CENTER OF DIVERSITY AND BROUGHT TO A NEW AREA AND IF THE CO-EVOLVING PARASITES ARE NOT BROUGHT TO THE NEW AREA, THEN THE PLANT OFTEN DOES MUCH BETTER IN ITS NEW AREA (BECAUSE THERE ARE NO DISEASES/INSECTS) THAN IT DID IN ITS OLD AREA.