Polyspermy is an event in which a female gamete is fertilized by multiple sperm cells resulting in an inviable zygote or dramatic changes in a species genome content. It is important to understand the mechanism driving the prevention of polyspermy events across all species as it increases viability by ensuring the next generation will inherit the correct amount of DNA. In flowering plants, reproduction occurs when a pollen grain containing two sperm cells lands on the stigma of a flower. The sperm cells travel inside a pollen tube, a cellular extension of the pollen grain, from the stigma to the female ovules where they burst into an area between the two female gametes: the egg and the central cell. Each sperm cell pairs with either the egg or central cell; two sperm cells almost never fuse with one female gamete. This mechanism of gamete pairing is essential for the success of a plant species and is key to understanding how plant species bypass fatal polyspermy events each time sperm are delivered. Some animal species possess a rapid block to polyspermy in which the egg plasma membrane depolarizes after fusion with one sperm preventing all other sperm from fertilizing the egg. We hypothesize that in flowering plants, there is a rapid block to polyspermy on the egg cell preventing multiple sperm from fusing with it. To address this hypothesis we are taking two approaches. The first approach involves utilizing genetically encoded fluorescent voltage sensors to test the plasma membrane of the egg and central cells for voltage potential changes at the moment of gamete fusion. The second approach is to analyze TMEM16A, a conserved chloride ion channel implicated in the block to polyspermy in animals, and to determine the role it plays during gamete pairing in Arabidopsis thaliana. The importance of determining the highly effective mechanism that drives the block to polyspermy is crucial in understanding how every sexually reproducing species is able to pass on a viable amount of genetic information to successive generations.
Perkins, Calvin J., and Nathaniel Ponvert, Mark A. Johnson, Laurinda Jaffe,
"Do Plants Have a Rapid Block to Polyspermy?"
(2021).
Summer Research Symposium.
Brown Digital Repository. Brown University Library.
https://doi.org/10.26300/jza0-sm56
Each year, Brown University showcases the research of its undergraduates at the Summer Research Symposium. More than half of the student-researchers are UTRA recipients, while others receive funding from a variety of Brown-administered and national programs and fellowships and go …
