"Glass" Opens a New Window for Seed Banks

Seeds contain little-known glass compounds that hold a valuable key to keeping them viable--information vital to seed banks.

When seeds freeze, their water and other cellular constituents have properties similar to the silica-based glass used to make windows. Glasses make seed cells very viscous, so molecules move slowly. The slower they move, the slower their chemical reactions--and the slower a seed's aging rate.

Seed aging is a critical issue at the National Seed Storage Laboratory in Fort Collins, Colo. Part of the Agricultural Research Service, the lab maintains the world's largest plant gene bank—some 300,000 accessions representing about 8,000 species.

Seeds stored at optimum conditions can last hundreds or thousands of years. That reduces the need to regrow seeds—the most expensive part of preserving germplasm.

The scientists' task is to determine how to keep stored seed alive and capable of germinating and producing fruiting parts years later. They continuously look for better ways to predict how seeds will respond to storage. They turned to seed glasses after getting the idea from food technologists, who use the glassy concept to study deterioration of frozen foods.

According to Christina Walters at the Fort Collins lab, the glassy concept explains how frozen seed cells respond to changing water contents and temperature. She has studied glasses in dried and frozen seed of at least 30 plant species including bean, pea, soybean and corn. She is looking for clues on the optimum combinations of water content and temperature for storing seed.

For more details, see the September issue of Agricultural Research magazine. The story about the seed glasses is also on the World Wide Web at:

http://www.ars.usda.gov/is/AR/archive/sep98/seed0998.htm

ARS is the principal scientific agency of the U.S. Department of Agriculture.

Scientific contact: Christina Walters, ARS National Seed Storage Laboratory, Fort Collins, Colo., phone (970) 495-3202, fax (970) 221-1427, chrisv@lamar.colostate.edu.