News and Stories

Guest blogger: Christina Del Greco, CREW Plant Lab Intern

Hi!  My name is Christina Del Greco. I’m a college sophomore studying biology at the University of Notre Dame. Thanks to a grant from the Association of Zoological Horticulture (AZH), I had the wonderful opportunity to be a plant lab intern with the Zoo’s Center for Conservation and Research of Endangered Wildlife (CREW) this summer.

As a CREW intern, I worked on the oak tree conservation project. Scientists store seeds in seed banks for many plants, especially endangered ones, as a precaution in case the wild population of a plant gets too low. However, you can’t do that for oak trees, as the acorns don’t stay viable if they are frozen. This means that there has to be another way to build up a bank of oak tissue. CREW has been pursuing oak stem tip culturing, in which the tips of oak seedlings are put into test tubes filled with media meant to help the plants grow. This way, we can store test tubes of seedlings instead of acorns.

The problem is there are so many different types of media with different concentrations of various nutrients the plants need, and each species grows differently than the others. My main project was to work on a Design of Experiments (DOE—a statistical method of setting up experiments) project in which 26 different types of media are used for four different oak species to compare growth on different media and gather data in order to compare them.

I took pictures of each of the plants after one month in culture, and then again after two months in culture. I also kept track of things such as whether the plants were infected by bacteria or fungus, how tall they grew, if the medium they were in turned brown, if any leaves were growing, and more.  All of these variables are able to potentially tell us something about what makes the oaks grow better or worse.

The data is sent to a collaborator at the United States Department of Agriculture (USDA) who knows far more about statistics than I do, and he can use the results to determine if any of the particular nutrients had a noticeable effect on the growth of the oaks. In the future, once all of the statistical results come back, we can use that data to create what we hope to be the optimal medium on which an oak shoot can grow.

I worked on a few smaller side projects as well. One was to try and determine at what point you should trim off the tip of an oak seedling to put it in the medium. Generally, we clip off the stem tips relatively early in the plant’s development, but there has never been any consistency, so I chose three relative stages in three different species and put them in culture to see which one grew best.

I also started a few petri dishes to try to initiate somatic embryogenesis, which is a process in which we try to force plants to make embryos by placing non-embryonic parts of the plant (somatic tissue), such as small leaves, on a special medium in the dark to try and force an embryo to form on its own.

And, when an incredibly old red oak tree fell in the middle of the Zoo, I had the opportunity to collect samples to see if there was any way we could regrow the tree in the future, allowing me the opportunity to use all of the methods I had learned about at once.

I learned so much over this internship. Besides learning all sorts of new lab techniques, I had no idea there were so many different ways to try and conserve different species of plants. I also didn’t know that there are so many different endangered oak trees. I am incredibly grateful for the opportunity I had to work at CREW for the summer and learn all about conservation efforts both here and at zoos and botanical gardens all over the world.