Carla Dizon
Year: 2017
Faculty Advisor: Wojciech Pawlowski

“Investigating the Impact of Polyploidization on Meiotic Recombination”

Project Summary:

Estimates suggest 30-70% of today’s angiosperms are polyploid (containing multiple chromosome sets), including many important agricultural crops, such as cotton, wheat, strawberries, and potatoes. Additionally, throughout evolutionary history, all plants have undergone polyploidization events, followed by chromosomal rearrangements and genome downsizing to become ‘diploids.’ The creation of viable progeny is dependent upon the ability to undergo meiosis successfully. Studies have been conducted to analyze meiosis in diploid plants, but much research has yet to be done on the meiotic events in polyploids. Although previous studies have shown that there are disruptions and errors in the early recombination stages in polyploids, we have little understanding of polyploidization’s effect on the later stages of meiotic recombination. In order to gain a better understanding of the evolution and adaptations of polyploid plants, the meiotic mechanisms and pollen viability of polyploid maize are studied.

Prophase 1, the longest stage of meiosis, involves two interrelated processes that are crucial in generating genetic variation: synapsis and crossing over. ZYP1 is a protein that is found in the central element of the synaptonemal complex and is used a marker for synapsis of synthetic maize polyploids. Super Resolution Structured Illumination Microscope (SRSIM) was utilized to observe the synapsis in synthetic polyploids. HEI10 is a protein which marks the sites of crossovers (COs). Immunolocalization slides for three-dimensional microscopy aid in the quantification of the number of crossovers in synthetic polyploid versus diploid maize. Pollen viability counts have shown that synthetic polyploid maize did not have a significantly lower percentage of viable male gametes compared to the diploids, suggesting that early errors observed in polyploids may be resolved before the completion of meiosis.

My Experience:

My internship here at BTI was wonderful. Through the multiple BTI seminars, I have broadened my view of what potential careers are available in plant science. It has also given me a better understanding and appreciation for all of the research efforts invested in plant science. Although I do not have a specific field of study in plant science chosen, I intend to pursue a career in research.

I had the opportunity to work in the Pawlowski Lab. Mischa, my mentor, has taught me different laboratory and microscopy techniques. She was an excellent mentor, who was very patient and understanding. She has also provided me with enough training and independence to be able to complete experiments and take care of the plants on my own. Wojtek, my PI, was present for most of the summer and was very helpful with my project and in answering my questions. Overall, my experience in the Pawlowski Lab has provided a working environment that was very supportive.  The most valuable lesson I learned from my mentor and PI was accepting that (sometimes) experimental results do not conform to expectations (or do not appear at all), but that is what science is about and one can still gain knowledge from the experience.