Plant scientist’s research reveals secrets of plants’ cellular communication

Gerry Berkowitz and graduate student Alice Zelman.

Professor of Plant Science Gerry Berkowitz may have cut his teeth on the music of the Grateful Dead, but through years of research he has unlocked a new, far subtler form of communication. He has identified how plants communicate on a cellular level.

Berkowitz, who holds degrees from Cornell (BS), Texas Tech (MS) and Brandeis (PhD), joined the University of Connecticut College of Agriculture and Natural Resources in 1996. He focuses his research, which has been supported by the National Science Foundation and other federal agencies since his arrival at UConn, on plant physiology and molecular biology. He has found that plants have internal signals that cells send to each other as warnings when parts of the plant are under attack by insects or disease.  Deep within the plant cells, a message goes out to produce material to repel the invading insect or fight back against the onset of disease. Berkowitz and his team of graduate students and postdoctoral fellows have characterized the system through which the word is passed along within a plant and to neighboring plants as well.

Typically growers and gardeners spray commercial pesticides on plants to kill insects or diseases. Berkowitz’ research suggests a new approach. When a greenhouse grower, for instance, observes that conditions are conducive to certain diseases, he can simply apply to the plant a peptide (corresponding to the plants’ own messages) that sends a message to its cells to produce specific chemical responses to prevent diseases or repel or kill insects. Rather than toxic chemicals, the plants essentially implement their version of an immune system to kick in and fight back. This protective strategy uses peptides that are naturally occurring within the plant’s own cells; they are not toxic to any organism in the environment and, as natural substances, they do not persist in the environment in a manner similar to some synthetic pesticides.

Unlike us humans, whose white blood cells fight infection by circulating throughout the body, plants don’t react as a whole. Every cell has to mount its own immune response. This complex reaction fascinates Berkowitz, who looks at the subtle way plants get signals and how they translate perception of these cues and signals into the activation of their ‘early warning’ defense systems.

As poetry is often more subtle than daily conversation, so too is the communication of plant cells. Berkowitz notes that when cells within a leaf, for example, sense a bacterial attack, they surround the invader within a bubble and encapsulate it to stop it from spreading to healthy cells. They may also signal neighboring plants to send out chemicals to attract predators or alert them that they are under attack and should start producing compounds to resist the threat.

Spraying bacterial proteins on plants can stimulate the plants to activate their own defenses rather than using pesticides to do the job. Some of these bacterial protein sprays are currently being used on a commercial basis. Berkowitz suggests that even these “next generation” environmentally benign pesticides could be replaced by using the plant’s own peptide messages to activate defenses.

Berkowitz’ previous research discovered how cells receive signals. New information unlocks what is sending the signals and how to match what happens inside a plant cell and what systems the plant cells use to communicate with other cells and to interpret the perceived messages.

Each plant species has its own, unique language, and each one is different. Just now Berkowitz and other scientists are identifying these signals in corn, wheat and tomatoes.  The complexity increases as the bacteria and fungi that attack plants have ways to alter themselves to essentially outwit the early warning defense systems of the plant cells upon which prey.

Berkowitz’ wry sense of humor can be found in the titles of some of his recent research articles, which include references to songs of Neil Young and the Grateful Dead: “Danger at Your Door: Pathogen Signals and Programmed Cell Death in Plants,” “The Grateful Dead: Calcium and Cell Death in Plant Innate Immunity,” “There’s More to the Picture Than Meets the Eye: Nitric Oxide Cross-Talk with Ca2+ Signaling ” and “Death Don’t Have No Mercy and Neither Does Calcium” are some examples of his subtle tributes to the rock and roll bands he enjoys.

Despite decades of research, Berkowitz retains a sense of wonder at the natural world.  While probing the intricacies of plant communication, he notes, “What’s really amazing is the power of the individual cell. To know nature is to see that it has amazing facets.”

By Nancy Weiss