Preliminary Seedling Competition Project
This past Spring semester, I was able to work as an undergraduate researcher in Dr. Emily Bruns’ Lab at the University of Maryland. I’m very grateful for this opportunity, and very excited to have the ability to organize, plan, and perform real science.
Originally, I joined the lab interested in work on sex differentiation in Silene, however that project proved to move slower than anticipated, so we decided to start this one to see some actual results this semester.
Dr. Bruns and I were interested in if the host-pathogen relationship between white campion (Silene latifolia) and anther-smut (Microbotryum lychnis-dioica) influences juvenile success. I conducted a density experiment where I created pots with 5 different seed densities, then inoculated half.
With this, we hoped to see some kind of trend between the proportion of disease and density. We initially thought that with increasing density, we would see less disease.
From the few data points that I did collect [another issue was timing and summer temperature rise], I did make some preliminary conclusions that our hypothesis was incorrect. We saw a lot of disease in the high density treatments, and none in our lowest density.
However, we couldn’t conclude this for sure, because it is possible the infection rate is too low for the low density treatment we did.
Overall, I had a lot of fun doing this project, but it did not succeed in the way we hoped. I plan to redo it in the Fall with a better set up when I return to the Bruns Lab.
Below, are updates from myself as the semester went along with my thoughts, progress, and general information on this project.
Chronology of Methods (What I actually did!!)
Feb 28 Determined desired pot size and density treatments
Mar 3 Seed counting to prepare for planting
Mar 4 Started strain cultures for inoculation
Mar 7 Planted seeds for control and experimental trials
Mar 10 Spore count and other inoculation prep
Mar 15 First inoculation treatment
Mar 22 Second inoculation treatment
Mar 24 Third inoculation treatment
Mar 30 Rescue and transplant a subset of seedlings
Apr 8 Moved from mist room to normal greenhouse
Apr 21 Data collection
Apr 26 Data collection
May 4 Data collection
May 12 Data collection
May 14 Analyze preliminary data
May 18 Submit write up of research project to Dr. Bruns
Study System
Healthy female Silene latifolia flower in the UMD Research Greenhouses.
White Campion | Silene latifolia
A flowering herbaceous plant of the “Caryophyllaceae” family (the carnation flower family!).
We refer to Silene latifolia as dioecious. This means it typically has separate male and female plants, with males producing pollen and females receiving it through vectors (pollinators) or wind to eventually fruit and create seeds.
Morphology of healthy Silene latifolia flowers and one infected with Microbotryum violaceum. (A) A healthy male flower lacking styles. (B) A healthy female flower lacking stamens. (C) An infected female flower with styles, stamens, and smut-induced anthers. Bar = 1 cm. (Kazama et al., 2005)
Anther-smut | Microbotryum lychnis-dioica
A fungal pathogen that infects the herbaceous plant Silene latifolia. Sterilizes its’ host by ‘hijacking’ the plant to stop making pollen and instead make spores (Baker, 1947). This is what we see as the “purple powder” in the photo to the left! You may also see me refer to the spores as sporidia.
It can be transmitted by pollinators from flower to flower or from flower to seedling. Additionally can be spread by wind or physical contact. It can only transmit when the plant is flowering!
My Experiment!
My experimental set up for the density treatments. “Densities” refers to the number of seeds I planted). “Replicates” means I made ‘3 copies’ to make sure no mistakes or errors ruined my experiment!
Density experiment! In addition to the above 30 pots, I also had a tray with one seedling per unit to get a germination rate independent of density.
This is where my biggest mistake came! I only did this one tray for germination rates, when I should have done two, and inoculated one. It would have been helpful to have a density controlled disease rate so that I could make actual conclusions on my density trend data.
The last thing other potting related thing I did was transplant some seedlings (after inoculation) from each density so that they could keep growing without competition pressure. This would have hopefully given me information on if competition was influencing the survival to adulthood whether they were infected or not.
Unfortunately…. those guys died. My transplanted seedlings got drowned by a watering error :(
Day 1 pots
Day 8 pots
Day 16 pots
Day 32 pots
Photo updates!
Some photos from the creation of the inoculation mix.
From left to right, top to bottom: green falcon tubes with water next to potato agar plates growing anther-smut fungus; hemocytometer under the microscope for counting sporidia; potato agar plate growing the fungus; blue falcon tube after adding stock sporidia mix in order to dilute.
Field site in Beltsville MD. Didn’t do any experiments out here personally, but I went out to help with weeding and data collection when needed!
Rescued transplants!
One of my experimental pots.
Control and experimental pots on March 15th in the greenhouse, after the first inoculation treatments.
Seedling transplants. Tag is about 2-3 in long.
Seedlings close-up.
Pots at the end of the semester!
Smutty flower!
More smut below.
