Chapter 7 



Maintaining Plant Diversity Offsite 



HIOHLIOHTS 



• Seed storage techniques are being used to conserve the genetic diversity of 

 cereals, legumes, and many other important crop species. Some plants, how- 

 ever, do not produce seeds that can be stored. Eventually, this problem may 

 be resolved with techniques for in vitro storage of plant tissue, from which 

 whole plants can be regenerated. At present, the main alternative to seed stor- 

 age is to grow entire specimens in the field. 



• New technologies, including cryogenic storage of seeds and clones, use of bio- 

 chemical methods to characterize accessions, and improved methods to detect 

 pathogens in plant materials transferred internationally, have the potential to 

 increase the cost-effectiveness of maintaining plant diversity offsite. Progress, 

 however, is constrained by a lack of fundamental research on plant physiol- 

 ogy, reproductive processes, and the mechanisms of genetic and cellular change. 



• Priorities and protocols for collecting and maintaining germplasm of major 

 crop plants are internationally coordinated. However, they are not well- 

 organized for minor crops or for wild plants that are endangered or have eco- 

 nomic potential. 



• Long-term public and private support for germplasm storage facilities depends 

 on whether the stored materials prove to be valuable. The use of offsite collec- 

 tions can be improved by characterizing the genetic diversity contained in the 

 collections and evaluating collections for important traits. 



• Major breakthroughs in biotechnologies might eventually lead to fundamental 

 changes in how biological diversity is maintained. Even so, a large portion 

 of public resources for technology development should be used in improving 

 the application of existing technologies, such as cryogenic storage of germ- 

 plasm, that are important to society but are not attractive to the private sector 

 to support. 



OVERVIEW 



One approach to maintaining plant diversity 

 involves collecting samples of agricultural and 

 wild species and storing them in offsite collec- 

 tions. Such collections can assemble agricul- 

 turally, geographically, and ecologically diverse 

 plants for use in crop improvement, genetic re- 

 search, or plant conservation. This chapter as- 

 sesses technologies of collecting, storing, and 

 using plants offsite. 



Obiectives of Offsite Cellectient 



Offsite collections of agricultural crops bring 

 together varieties and related species from 

 widely dispersed areas (box 7-A). These collec- 

 tions conserve plant genetic resources threat- 

 ened with loss or extinction. They also serve 

 as a convenient source of new genes for public 

 and private plant improvement. The highly suc- 



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