Document Type



Molecular & Cell Biology; Spanish


Prof. Yi Li, Dept. of Plant Science & Landscape Agriculture


Genetics and Genomics | Plant Breeding and Genetics | Plant Sciences


Commercially produced tomatoes are typically harvested well before maturation in order to withstand domestic and international distribution. While this process ensures unspoiled goods, the nutritional value of the fruits have been curtailed as a result of premature harvesting. Previous research has found that the polygalacturonase gene (PG gene) is responsible for cell wall degradation of the tomato. In this study, CRISPR/dCas9 technology was employed to increase methylation levels in the promoter regions of the PG gene. This method is significant in that it epigenetically modifies the tomato genome using a technique that has the potential to develop non-genetically modified progeny with enhanced nutrient accumulation. This alteration could lead to decreased PG expression, thus delaying the weakening of the cell wall of the tomato. By delaying this softening, farmers can harvest tomatoes at a later growth stage, thus improving the nutritional value of the product. Although my time to work on the project has been limited, Agrobacterium-mediated genetic transformation of tomato plants and various laboratory and greenhouse techniques were learned. More importantly, tomato plants that express GFP and dCas9-PG-gRNA have been produced, a significant step for the project. Characterization of the plants that express dCass9 and PG-gRNA will allow us to verify whether dCas9 can be used to enhance DNA methylation levels of the promoter region of the PG gene, consequently extend the ripening period of tomatoes on the plant, and boost their nutritional value.