Image of pitcher plant, S. purpurea, by Jessica Stephens (Ph.D., ’17), currently a Conservation Coordinator and Research Scientist at the Atlanta Botanical Garden.
By Alan Flurry
Researchers in the UGA department of plant biology have published the first genetic linkage map for what has long-been an object of human fascination: plants that have evolved the capacity to capture and digest insects. Lead author Russell Malmberg explains:
“We normally think of plants as being eaten by animals, but a small number of plant species have reversed this and are able to capture and digest insects. These carnivorous plants can obtain part of their mineral nutrition this way, aiding them to grow in nutrient poor environments such as wetland bogs. This carnivorous habit is estimated to have evolved at least 10 times independently, resulting in multiple different adaptations and mechanisms for insect capture and consumption. Darwin (1888) was so taken with the unique adaptations of these plants that he used the word “wonderful” fifteen times in his descriptions of them. Scientists have studied these plants to understand how they attract insects, kill them, digest them, absorb the nutrients, and then process the nutrients to help the plants grow. Carnivorous plants have interactions with microbes, insects and other animals, as well as other plants and hence are of interest for their role in unique ecological communities. Some familiar examples of carnivorous plants are: the pitcher plants (Sarracenia, Nepenthes) which capture insects in a pitcher-shaped container often containing a pond; Venus fly-traps (Dionaea) which have a trapping structure that closes in response to triggers of tiny hairs; and, sundews (Drosera) which capture insects using sticky mucilage from glands. All three of these examples are based upon different evolutionary modifications of their leaves.
The team report the first genetic linkage map for Sarracenia pitcher plants, including placing the genetic basis of 64 pitcher traits on the linkage map. A genetic linkage map differs from a genomic DNA sequence; it is complementary to a full DNA sequence. Some other carnivorous plants have had their full genome sequences determined, but there has not previously been a genetic linkage map. An important use of a genetic linkage map in current biology is helping to dissect or determine the relationship between the DNA sequence and the final shape and function of the organism – its traits and how they function, relating the genotype to the phenotype.
“This study is a beginning, a first step towards providing a final genetic map and discovering the genetic basis for traits that will help us understand the mechanisms of insect capture and digestion in these carnivores,” Malmberg said.
The full study is available here.