We had an incredible time hunting pathogens in Kirstenbosch National Botanical Garden with a group of home school students (Se7en) in early November. The students were avid learners and natural citizen scientists, contributing much excitement to the afternoon's research extravaganza.
We spent the afternoon with two of the garden managers who have been battling root rot pathogens—microorganisms that attack plant roots and cause disease. The managers were kind enough to save some of the diseased plants for us to sample. Below are a few photos of us collecting plant samples. Each student collected at least one sample.
A citizen scientist using a knife to expose a lesion likely caused by Phytophthora cinnamomi. When isolating Phytophthora, we tried to collect pieces along the margin of living and dying tissue, because this was where the pathogens were still active. It was also critical to sterilize equipment/tools in between samples, to ensure we were not spreading the pathogens or contaminating our samples.
We sterilized our tools in between samples by dipping the blades in ethanol and heating them with a lighter. Bleach or rubbing alcohol would also work. It was fun, but also educational!
We collected samples of leaves, stems, and roots for many different plant species present within the Proteaceae garden. Everyone had collected at least one sample by the end of the afternoon.
After collecting samples of dying plants, the next step was to try to isolate a species of Phytophthora. Phytophthora are not the only microbes causing disease in the fynbos, but it is the group that we are focusing on for our research. Phytophthora species cause serious issues around the world (e.g. Sudden Oak Death and the late blight of potato), and there is a lot to be learned about them in the fynbos. For more information about Phytophthora, see our previous blog post:
To isolate Phytophthora from our dying plant samples, we cut small pieces along the disease margin and placed them into selective agar media. This media has all of the nutrients that Phytophthora need, as well as some antibiotics to prevent growth of other fungi we are not interested in.
After we place the plant tissue pieces in the selective agar media, we watch carefully and replate the organisms that look like Phytophthora until we have a pure culture. Sometimes it takes many isolations before we have a pure Phytophthora culture.
We hope you enjoyed this blog post. Please contact us if you would like to organize a similar activity! Special thanks to Se7en and the managers at Kirstenbosch for a epic afternoon!
If you would like to see the activity from Se7en's perspective, you can see their incredible blog post about the afternoon here!