UF Researchers Attempt To Conserve Endangered Plant

Eric Benjamin Lowe

Gayle van de Kerckhove (352) 846-6064

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GAINESVILLE—A rare species of St. John’s Wort found only in four counties of Central Florida is disappearing, and University of Florida researchers are studying the plant’s genetics and local environmental conditions in hopes of conserving it and other endangered plants.

Little was known about what could be causing the dieback of the Edison’s St. John’s Wort, a close relative to the popular herbal supplement for depression.

“What we know about disease in plants in large part comes from agricultural research on crops like corn, soybeans and tomatoes,” said Gayle van de Kerckhove, a doctoral candidate in the department of plant pathology at UF’s Institute of Food and Agricultural Sciences and one of the key researchers of Edison’s St. John’s Wort. “So studying disease dynamics in wild plant populations is a relatively new frontier.”

Van de Kerckhove works in what could be considered the last of the “real Florida” habitats — the Lake Wales Ridge, which consists of the ancient sand dunes and shorelines of prehistoric Florida that run down the center of the state. The region harbors an extraordinarily high number of plant species that are found only in Florida and nowhere else in the world. This high number of rare and endangered plants rivals that found in Hawaii and California.

The Edison’s St. John’s Wort is found in DeSoto, Glades, Highlands and Polk counties in shallow, seasonal ponds that hold few nutrients. The plant endures standing water in the rainy spring and summer months, then survives the drying of the ponds and bakes in the dry season. The region also is the lightning capitol of the United States and for centuries has had fire influence the make-up of the vegetation.

Van de Kerckhove said the Edison’s St. John’s Wort is infected with two newly recorded fungal diseases, anthracnose and twig blight, which can infect a wide range of plant species. The anthracnose disease has recently attacked commercial plantings of St. John’s Wort in the Carolinas.

How the diseases were introduced into Florida’s wild plant communities is not yet fully understood. Researchers are unsure whether the pathogens play a major role or if they are merely symptoms of other environmental stresses harming the plant, said Tim Schubert, the chief plant pathologist with the Florida Division of Plant Industry in Gainesville.

“Plant extinctions do happen naturally apart from human intervention, but with all of us involved in a global environment, it’s hard not to be willing to take some blame for this,” said Schubert.

He said the benefits of the research may not be immediately apparent, but what is learned in the process may assist with the treatment of agricultural and pharmaceutical crops or with other endangered plants.

Schubert added that the potential effect on the area ecology from the loss of the plant is unknown, as is the possible pharmaceutical benefit the plant may have to humans.

So far the research has unearthed some interesting traits about the St. John’s Wort. Van de Kerckhove began studying the endangered plant believing that its isolated pond populations reproducing over thousands of years would likely result in low genetic variability, making the plant more vulnerable to devastating diseases. Surprisingly, she said, the plant appears to be genetically diverse, both within individual ponds and across many ponds.

“This is the good news about this species, but these ponds continue to be wiped out throughout the Lake Wales Ridge,” van de Kerckhove said. “There are dozens of different species of St. John’s Wort throughout the world, and numerous studies have shown these plants to be active against bacteria, fungi and even viruses. The pity is that we may lose plants like Edison’s St. John’s Wort right here in Florida before we even get a shot at learning what they can do as wild organisms or to benefit us.”