Where Do New Plants Come From? 



Dr. Owen M. Rogers 



TT/^r hat do New Guinea impatiens, dawn red- 

 \/\/ wood (metasequoia) and grain amaranth have 

 Y Y in common? They were all plant introductions 

 through the United States National Germplasm System. 

 One of the great national treasures in this county is 

 the collection of germplasm from around the world 

 that maintains and stores genetic diversity for future 

 generations. 



America's abundant and inexpensive supply of food 

 and fiber is based on intensive agriculture. Intensive ag- 

 riculture benefits from genetic uniformity in crops. But 

 genetic uniformity increases the potential for crop vul- 

 nerability to new pests and stresses. Genetic diversity 

 gives us the sustained ability to develop new plant vari- 

 eties that can resist these 



Each of the four regional stations has a technical advi- 

 sory committee of local scientists. The Northeast Re- 

 gional Station at Geneva, New York, has an ornamental 

 subcommittee that is responsible for testing promising 

 new or unproven woody ornamentals in the Northeast. 

 At the present time, the closest New Hampshire evalua- 

 tion plot is at the university in Durham. Over the years 

 it has tested a number of plants that have become stan- 

 dards in the field, such as the Rhododendron hybrid 

 'Olga Mezitt', Microbiota decusata, and Belamcanda (the 

 Blackberry Lily). The list of plants still under test in 

 Durham include two disease-resistant elms, three weige- 

 las ('Red Prince', 'Samba' and 'Minuet'), and several of 

 the "bud hardy" forsythias, as well as selections from the 



National Arboretum and 



pests, diseases, and envi- 

 ronmental stresses. 



Wild ancestors and rela- 

 tives of cultivated plants 

 are the keys to genetic di- 

 versity. But the amount of 

 land where plants grow 

 wild continues to shrink 

 and many plant species 

 and varieties are disap- 

 pearing forever. The Na- 

 tional Plant Germplasm System exists to store and cata- 

 log germplasm of plants that might otherwise be lost. In 

 the highly populated world of our future, some of these 

 plants may help make the difference between abun- 

 dance and scarcity. 



There has always been a thriving business in seed 

 and plant exchange since early colonial days with 

 people such as Catesby and the Bartrams making a good 

 living sending plants to England In reverse, Benjamin 

 Franklin and Thomas )efferson often sent home seeds 

 and cuttings to be tried in the colonies. A great many of 

 today's commonly grown plants have come into this 

 country fairly recently. For example, forsythia was not 

 known until 1850 and it wasn't until 1946 that we offi- 

 cially started a plant introduction program 



Four regional plant introduction stations maintain 

 working collections of seeds. A working collection dis- 

 tributes germplasm to meet the day-to-day needs of re- 

 search scientists — a kind of gene bank checking account. 

 The regional stations store thousands of plant species 

 and varieties; other working collections across the coun- 

 try concentrate on only one crop or type of crop, such 

 as potatoes or small grains. Finally, since many fruit, nut, 

 and landscape varieties lose their varietal identity when 

 they're stored as seed, this germplasm is preserved as 

 living plants at the ten national clonal germplasm re- 

 positories. 



vrild ancestors and relatives of 



cultivated plants are the keys to 



genetic diversity. 



But the amount of land where plants 



GROW WILD continues TO SHRINK AND 



MANY PLANT SPECIES AND VARIETIES ARE 



DISAPPEARING FOREVER. ^ 



the North Central Plant In- 

 troduction Station at 

 Ames, Iowa. 



Also part of the national 

 system is the National 

 Germplasm Resources La- 

 boratory at Beltsville, 

 Maryland It is the hub for 

 plant exploration activities 

 and a clearinghouse for 

 exchange of plant germ- 

 plasm with foreign countries. 



Depending on species, dry seeds can last anywhere 

 from a few years to centuries. Conventional storage in 

 gene banks requires drying the seeds to 6 percent mois- 

 ture or less, sealing them in moisture-proof containers, 

 then storing them at temperatures held from just above 

 freezing (5°C) to well below (-20°C). These methods 

 have been fairly reliable for most crops. But some spe- 

 cies have short-lived seeds that are difficult to store. For 

 these seeds, other methods are needed. 



Researchers at the National Seed Storage Laboratory 

 are developing new ways to store germplasm. Cryo-pres- 

 ervation (a type of freezing) in or over liquid nitrogen at 

 -I96°C is the most highly developed of these new tech- 

 niques. The lab is now storing seeds routinely in liquid 

 nitrogen. 



ARS scientists are also experimenting with biotechnol- 

 ogy to test, grow, and preserve plant germplasm Tissue 

 culture techniques are well advanced for many species, 

 and scientists are evaluating these techniques for those 

 species that can't be stored as seed. Tissue culture is a 

 cloning method — growing a whole plant from a small 

 plant part in an artificial medium in a controlled, dis- 

 ease-free environment. It's easier said than done, be- 

 cause techniques may be specific to one crop; solving 

 problems for one crop doesn't solve them for all. 



Besides doing research on seed longevity, scientists 



lune & |uly 1995 



