Ice-minus Bacteria - Historical Perspective

Historical Perspective

In 1961, Paul Hoppe of the U.S. Department of Agriculture studied a corn fungus by grinding up infected leaves each season, then applying the powder to test corn for the following season to track the disease. A surprise frost occurred that year, leaving peculiar results. Only plants infected with the diseased powder incurred frost damage, leaving healthy plants unfrozen. This phenomenon would baffle scientists until graduate student Stephen Lindow of the University of Wisconsin–Madison with D.C. Arny and C. Upper found a bacterium in the dried leaf powder in the early 1970s. Dr. Lindow, now a plant pathologist at the University of California-Berkeley, found that when this particular bacterium was introduced to plants where it is originally absent, the plants became very vulnerable to frost damage. He would go on to identify the bacterium as P. syringae, investigate P. syringae's role in ice nucleation and in 1977, discover the mutant ice-minus strain. He was later successful at developing the ice-minus strain of P. syringae through recombinant DNA technology as well.

In 1983, a biotech company, Advanced Genetic Sciences (AGS) applied for U.S. government authorization to perform field tests with the ice-minus strain of P. syringae, but environmental groups and protestors delayed the field tests for four years with legal challenges. In 1987, the ice-minus strain of P. syringae became the first genetically modified organism (GMO) to be released into the environment when a strawberry field in California was sprayed with the ice-minus strain of P. syringae. The results were promising, showing lowered frost damage to the treated plants. Dr. Lindow also conducted an experiment on a crop of potato seedlings sprayed with ice-minus P. syringae. He was successful in protecting the potato crop from frost damage with a strain of ice-minus P. syringae.