Ripening in fleshy fruits is a tightly regulated process aimed at making the fruit appealing to seed-dispersing organisms. The accumulation of key nutrients during ripening also makes fleshy fruits important for a balanced diet. However, unlike staple crops (e.g., maize and rice) fleshy fruits have a limited shelf life before they begin to rot. One way to address this problem is to control when the ripening process is initiated. In this study we utilized tomato, the primary model for fleshy fruit ripening. While a general model of ripening regulation in tomato has been established, the initiation of ripening is not well understood. One clue however, is that ripening begins in the locule (i.e., gel-like tissue that surrounds the seeds) and moves outward, raising the logical question of whether or not seeds initiate or influence ripening. To test this question, we employed a system for hormonal induction of parthenocarpy (i.e., fruit development in the absence of fertilization) to produce developmentally synchronized seeded/seedless fruits. We then determined if/how key ripening parameters were altered in the absence of seeds. First, we observed liquefaction of the locular gel was significantly delayed in seedless fruits, suggesting seeds may play a role in changes prior to the start of ripening. In addition, we found a significant reduction in the levels of several carotenoids in the flesh of parthenocarpic fruit, but failed to detect a difference in the production of ethylene (a key ripening hormone) during ripening. Future work will aim to better characterize the alterations in ripening observed here through transcriptomic and epigenetic approaches.
Working at the Boyce Thompson Institute this summer has been a life changing experience. I performed many new techniques as well as learned new ways to perform techniques I had done in the past. It was also fun doing hands on work in the greenhouse while also doing molecular work in the lab. I thoroughly enjoyed working with my mentor. He not only taught me proper lab etiquette but also showed me what it is truly like to be a graduate student. It was also a pleasure working with everyone else in the Giovannoni lab. Working forty hours a week had prepared me for graduate school as well as a career in plant science. This internship has furthered my love and admiration for plant research.