Every spring, California farmers have to be on the lookout for signs of frost. Faced with the prospect of losing an entire season’s harvest, growers spend millions of dollars a year on heaters, wind machines, sprinklers and even helicopters to keep cold air at bay. Now, a scientist has done some groundbreaking research, linking frost damage to plant-dwelling bacteria. This might result in better ways to fight frost.
Steven Lindow is a plant pathologist at the University of California, Berkeley. More than 40 years ago, he proved that frost-sensitive agricultural crops harbor a bacteria called Pseudomonas syringae that cause ice to form at above-normal freezing temperatures. The bacteria are so adept at making ice that they have been added to snow machines at ski resorts for years now.
Despite battles with anti-GMO activists who derailed his early work, Lindow has continued to refine his approach ever since. A central focus involves exploiting the science of microbial ecology to enlist beneficial bacteria and other tools to displace ice-promoting strains. Creating conditions unfavorable to harmful strains could reduce dependence on fuel-hungry equipment and conserve water during dry years, which will become more common as the world warms.
Plants are about 90 percent water, and sustain frost damage when ice crystals form between cells and pierce their membranes. In the absence of substances that make ice, they can “super cool,” or remain liquid at sub-freezing temperatures, Lindow said, contrary to the conventional wisdom that water always freezes at 32oFahrenheit.
Lindow’s “ice minus” mutant bacteria—viewed by scientists as a landmark scientific achievement—triggered protests from consumers wary of genetically modified organisms and legal challenges that delayed testing for four years. He finally won approval to test his engineered bacteria in strawberries and potatoes in the late 1980s, after spending about $100,000 to meet the Environmental Protection Agency’s regulatory requirements.
