Full Bloom

If the biological clock ticks relentlessly for humans, it can be even harsher for plants, specifically annuals, which have a lifecycle of a single year. In order to bear seeds and reproduce, annuals must switch from a growing phase to a flowering phase when the temperature, light, and soil nutrients are ideal. If plants flower too soon, their seed yield is sparse. And if they flower too late, they will not be able to produce seeds before the harsh winter. 

This transition into flowering is the subject of a recent Science article co-authored by Professor of Biology Doris Wagner, a developmental biologist who studies how structures form in plants.

“Plants change from a vegetative to a flowering state by responding to intrinsic and environmental cues, and it is an incredibly complex process,” Wagner explains. “They are even able to sense their competition—how many other plants surround them. My lab is investigating transcription: Which genes encoded in the DNA are being activated to trigger flowering and how the plant knows when to do this.”

Wagner’s research has significance not only for the survival of a plant species but also for the planet’s food supply, as well as biofuel production. Most crops are grown as annuals, so their successful reproduction is crucial for human sustenance.

“The food supply is also threatened by increased population growth and the decrease in available arable land due to climate change,” Wagner says. “We must learn how to generate a higher yield of crops with less land and also gain understanding of how to make plants drought-tolerant.”

Professor Wagner also studies epigenetics—the study of chemical reactions that activate and de-activate the genome.

“How can it be that all cells in an organism have the same DNA but give rise to different cell types and structures?” Wagner asks. 

The answer to that question is that not all of the genome information is visible in each cell type—only what is needed to make it a heart cell or a leaf cell. Defects in epigenetics underlie many diseases, such as cancer, and epigenetics also controls memory and aging. In plants it helps them cope with changing environments.

When studying the regulatory mechanisms of plant epigenetics, Wagner sees an overlap between plants and humans—and this informs knowledge about human health. “This is why the National Institutes of Health funds a significant part of plant epigenetic investigations,” she says.

Wagner plans to take a sabbatical in Germany to learn new research techniques at the Max Planck Institute for Plant Breeding Research in Cologne. There she will hone her knowledge about molecular biological research on plants. When she returns to Penn, she will be teaching a class in epigenetics and she will also lecture on transcription in an introductory biology course.

“If one could isolate a moment in history when it is imperative to understand how plants monitor and adapt to different environments, for example in the switch to making flowers, we have arrived there,” Wagner says. “The survival of animals is dependent on the survival of plants.”