Ch. 7— Maintaining Plant Diversity Offsite • 179 



Table 7-2.— Technologies and Practices To Detect Pests and Diseases of Quarantine Significance 

 and the Pathogens To Which They Are IMost Frequently Applied 



Technology/practice: 



Description Range^ 



Physical examination: 



Physical manifestations of disease-producing agents A 



Seed tiealth testing: 



Germinating seed in culture conditions that allow growth of fungi or bacteria. Microscopic 



examination of seed for pathogens B,F 



Grow-out testing: 



Growing plants under controlled conditions until diseases are no longer detected B,F,V,0 



Indexing: 



Attempted transfer of pathogens from a plant under examination to another species that is highly 

 sensitive to infection by them. Can involve transfer by mechanical abrasion with extracts 



or by grafting B,F,V 



Electron microscopy: 



Examination of extracts or tissues for the presence of pathogens or their spores B,V 



Inclusion bodies: 



Light microscopic examination of tissues for structures characteristic of pathogen infection B,F,V 



Serologic testing: 



An array of procedures utilizing the ability of test animals to produce antibodies that are highly 

 specific for a particular pathogen. Important variations include enzyme-linl<ed immunosorbent assay, 



radioimmunosorbent assay, and immunosorbent electron microscopy B,V,0 



Polyacrylamide gel electrophoresis: 



Detects ribonucleic acid (RNA) of pathogens in small amounts of tissue B,V,0 



Nucleic acid hybridization: 



New technology that uses recombinant DNA procedures to locate the genetic material of a pathogen 

 in DNA extracted from tissue samples B,V,0 



^A = Most pests and pathogens. B = bacteria; F = fungi; V = viruses; = ottiers (e.g., mycoplasmas, viroids). 



SOURCE: Based on data from R.P. Katin, "Technologies To f^aintain Biological Diversity; Assessment of Plant Quarantine Practices," OTA commissioned paper. 1985. 



Table 7-3.— Storage Technologies for Germplasm of Different Plants 



Storage technology^ 



Plant group 



Cereals and grain legumes 



(wheat, corn, barley, rice, soybean) 

 Forage legumes and grasses 



(alfalfa, orchardgrass, bromegrass, clover) 

 Vegetables 



(tomato, bean, onion, carrot, lettuce) 

 Forest trees 



(pines, firs, hardwoods) 

 Roots and tubers 



(potato, sweet potato, tropical yam, aroids) 

 Temperate fruit and nuts 



(apple, grape, peach, strawberry, raspberry) 

 Tropical fruit and nuts 



(avocado, banana, date, citrus, papaya, cashew) 

 Ornamentals 



(carnation, zinnia, lilac, rhododendron) 

 Oilseeds 



(soybean, sunflower, peanut, oilpalm, rape) 

 Nevi/ crops 



(jojoba, amaranth, guayule) 



^X = currently in use; R = under research and development. 



"Refers to source of materials for storage (e.g.. plants are the source ( 



^B = base collections available; A = active collections available 



} of materials for initiating tissue cultures. 

 SOURCE: Adapted from L. Towill, E. Roos, and P.O. Stanwood, "Plant Germplasm Storage Technologies," OTA commissioned paper, 1985. 



