In the event of a catastrophic occurrence that would threaten a plant species with extinction, special facilities have been developed in countries around the world to store seeds in very cold, very dry conditions – and with thorough documentation – so that the plant might be reproduced.
There are some “exceptional” plants that cannot be included in such seed banks, however, and for those plants, the data and the record keeping are less clear.
To fill the gap, University of Delaware graduate student Sara Helm Wallace has stepped in to create a resource that catalogs all of those plants found in the United States and Canada that cannot be seed banked.
Helm Wallace, who is a master’s degree student in the Longwood Graduate Program, said she is carrying on work that was started by the Botanic Gardens Conservation International (BGCI) organization.
The plants she is interested in are those known as “exceptional” because they produce seeds that cannot be preserved in seed banks for a variety of reasons – they produce few or no seeds, they cannot be easily propagated by seed, or they produce seeds infrequently.
“There are a lot of plants that do produce seeds but for whatever reason, their seeds are not viable and they don’t germinate into new plants,” she said. “And there are a lot of plants that produce seeds but they’re in a location in the seed production season such that humans can’t get to them.”
Although these exceptional plants cannot have their seeds stored in a bank, that does not mean that they cannot be preserved, Helm Wallace said.
“A lot of brilliant work is being done on exceptional plants – finding ways to store them and then to propagate them later on – but we don’t have a single source where we can go to find information on these plants,” Helm Wallace said. “That’s where I’m coming in – I’m developing that single source.”
Seed bank storage techniques
Some of the seed bank storage techniques include taking a tissue culture, a horticultural practice in which an embryo or a piece of leaf, stem, root or bud of a growing plant is taken and given nutrients. Those pieces are then bombarded with different kinds of plant hormones and grow into new plants.
“You can take a small leaf of a plant, depending on the plant, and get hundreds and thousands of new plants out of that leaf over time,” said Helm Wallace. “You might grow a new plant with these hormones and then you can cut that piece up and grow 100 plants from those cuttings, and it just goes on from there.”
Another way of storing these exceptional plants is known as cryopreservation, a popular example of which Helm Wallace said can be found in Star Wars.
“I was just looking at the clip where Han Solo is put in the carbonite and then he’s brought to life again and this is just like that. That’s what cryopreservation is. The plant part – perhaps a leaf bud – is put into liquid nitrogen and stored there for a number of years and then they are pulled out of liquid nitrogen. The cells are basically frozen in time and then pulled out of the liquid nitrogen and, given the proper nurturing, maybe a kiss from Princess Leia, can actually grow,” Helm Wallace said.
Creating the catalog
For her work creating the catalog, Helm Wallace said she is currently working on U.S. and Canadian plants but hopes to expand that to a global list and carry on her research once her master’s degree work is completed.
So far, she has compiled a list of 290 exceptional plants that are threatened and whose conservation needs are crucial.
Helm Wallace said there are 290 threatened exceptional species identified in the U.S. and Canada, but that she has asked 114 conservation professionals in North America to help advise her on a list of almost 6,000 other species because their exceptional status is unknown.
“In other words, we don’t know if they can be seed banked or not and we don’t know who is working on them and where,” said Helm Wallace.
Some examples of exceptional plants that Helm Wallace has cataloged include Lobelia boykinii, which Helm Wallace said is “a globally as well as locally imperiled species that is native to the coastal plain from New Jersey and scattered all the way down to Florida, Alabama and Mississippi. Lobelia boykinii used to be here in Delaware, specifically Sussex County, but is no longer found here.”
Helm Wallace said there are people working on preserving the plant through cryopreservation or tissue culture. “The implications are that, if there was a need to reintroduce the plant to Delaware, the data I am compiling would be housed in a well-curated database that would be an easy resource for anyone to go to so that they could find out who is working on the preservation of this species.”
Helm Wallace also said that there are at least 25 species of oak on the list that are not currently seed bankable.
“Can you imagine if our forests lost oaks to some sort of pest or disease? It should be easy to go to a database to find out who the experts are in oak tree preservation and propagation, so that we could repopulate our forests – assuming the pest or disease was controlled,” said Helm Wallace.
Now that Helm Wallace has worked on a list of exceptional plants for the U.S. and Canada, she is vetting databases and comparing them to find out what would be a suitable, well-curated, constantly updated online site for people to go to find the list of exceptional plants.
Helm Wallace plans to finish her thesis by July but she is hoping to write grants to get more funding to carry this project to the global level. “Wherever I end up in life, I am hoping to continue this project,” she said.
Article by Adam Thomas
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