Investigating the Impact of 1-Methylcyclopropene and Gene Editing on Physalis grisea Abscission

Fruit abscission is a necessary process for many plants, and describes the shedding of fruit from the stem. This process spreads seeds, which is important for advancing the next generation of that species. Sometimes, fruit will abscise before they are ready to be harvested, which can be a detriment to crop harvest, especially in large-scale agricultural settings. This premature fruit abscission is especially prevalent in Physalis grisea, also known as groundcherry, which hinders its adoption as a widely-grown agricultural crop. Two separate strategies were explored to investigate solutions to groundcherry fruit abscission: applying 1-Methylcyclopropene (1-MCP), a synthetic growth inhibitor, and editing the plant genome for genes that cause fruit abscission. Applying 1-MCP to fruit is known to delay ripening, and studies have shown that there is an association between abscission and fruit ripening in plants like tomatoes. We hypothesized that 1-MCP application would result in slowed groundcherry ripening and thus decrease rates of abscission. Our experiment consisted of three treatments: an untreated control, a treated control, and a 1-MCP treatment group. The 1-MCP treatment consisted of 1-MCP powder dissolved in distilled water and surfactant solvent, while our treated control group received the solvent without 1-MCP. After treating the fruit, we recorded the total number of fruit that dropped approximately every other day for 21 days. The second experiment observed the effects of editing the groundcherry genome. INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) and JOINTLESS are two groundcherry genes that are known to be involved in abscission zone (AZ) development and cell separation, which play an important role in the detachment of groundcherry fruit. When these genes were edited in groundcherry via CRISPR/Cas9 , we expected reduced AZ development and a drop in fruit abscission rates. To test this hypothesis, wild type groundcherry, ida mutants, and jointless mutants were randomly assorted in the greenhouse and flowers were tagged weekly. After four weeks of tagging, a force meter was used to measure the force required to remove the fruit of varying developmental stages from the plants. A necessary step in improving the quality of groundcherry fruit harvest is determining the best method to reduce abscission. These experiments serve as an early assessment of the effectiveness of current methods of groundcherry abscission reduction, and similar experiments at a larger scale can be derived to optimize groundcherry cultivation.

When I first heard about CRISPR technology, I was confused but very excited by the potential to make something new. I saw myself developing a grass that my mom could plant on our lawn to outgrow the ever-persistent weeds. Before making this plant, though, I had to learn about the technology, so I reached out to Joyce Van Eck and asked to join her research. She graciously welcomed me to the lab, despite my lack of experience, and I worked with Elise Tomaszewski throughout the beginning of 2023. Elise taught me every step of transformation, and in return, I provided some very gnarly-looking contaminated plates. I am so grateful for the members of the Van Eck lab, who all showed me patience and kindness and made the experience a ton of fun. During the REU program, I got to meet students from around the country who were even more excited than I was about plant science. I’ve made some very good friends who I know are going to change the world.