Freja Gudmundsson
Faculty Advisor: Jocelyn Rose
Year: 2015

Change in the cell wall polysaccharide landscape throughout tomato fruit development and ripening

Project Summary

The textural changes exhibited by tomato fruit during ripening involve the action of enzymes that catalyze partial or complete depolymerization and solubilization of cell wall polysaccharides. Cell walls also undergo major remodeling during organ growth. This study was conducted as part of a study to investigate the cell wall polysaccharide structural dynamics of the tomato fruit during development, targeting early fruit growth as an initial stage of the longer term project. Cryosectioning was performed on OCT (optimal cutting temperature) embedded tomato fruit tissue collected from fruits at the anthesis stage. These sections were subsequently labeled with primary antibodies that recognize pectic homogalacturonan and/or hemicellulosic xyloglucan epitopes, as well as a secondary antibody, which was TRITC (tetramethylrhodamine)-conjugated. The immunolabeling was then visualized using a fluorescence microscope. No major differences were observed between the sections labeled with the different antibodies, though there were a slight difference in signal intensity between the ovaries and other tissues.  It was concluded that both homogalacturonan and xyloglucan are present at anthesis. The techniques developed here will be used to perform a more extensive study, using a larger range of antibodies, to characterize a developmental series of tomato fruit tissue, from anthesis to the red ripe stage. This research is important as it will reveal new aspects of the wall architectural changes that accompany fleshy fruit ripening, thereby improving our understanding of the softening process. Ultimately this may suggest strategies to extend fruit shelf-life, reduce spoilage and facilitate the transport and storage of fleshy fruit crops.

My Experience

During my summer internship in the Rose lab as part of the REU program I have learned a lot. I have gained essential laboratory technique and research skills that will be useful in my future studies. I have for the first time worked independently on a daily basis on a laboratory project, under the supervision of a mentor. It was a great experience to work with Iben Sorensen, and I greatly appreciate how patient she has been with me. In this past month my own patience has been tested every day and I have learned that instead of giving up when something does not work the first time, I just need to keep trying until it works. It has been such a pleasure to spend my summer here at Cornell, and I’m very grateful to everyone who has helped me, especially Jocelyn Rose, Iben Sorensen, Nicole Waters Fisher and Tiffany Fleming.