Allyson Weir
Faculty Advisor: Carmen Catala
Year: 2018

“Functional Characterization of the Tomato Sugar Transporter SWEET10”

Project Summary:

Carbohydrates produced from photosynthesis are crucial to development, growth, and signaling in plants. To maintain optimal plant function, sugars must be moved from the leaf to other areas of the plant by transporters. A novel class of sugar transporters, named Sugar Will Eventually be Exported Transporters or SWEETs has been shown to play a key role in sugar efflux during several physiological processes, however little is known about their role in fruit development. It has been hypothesized that the action of SWEET transporters is needed in specific fruit tissues and stages, allowing efficient utilization of sucrose during fruit and seed development. However, direct molecular genetic evidence of this hypothesis is still lacking. My project aims to elucidate the role of the tomato SWEET transporter, SlSWEET10, in regulating sugar transport during early fruit development. SlSWEET10 is specifically expressed during early fruit development, and mostly in vascular rich tissues such as the columella and the placenta. The SWEETs gene family is split into four clades, with SlSWEET10 belonging to Clade III. In Arabidopsis, several Clade III SWEETs are known to transport sucrose, therefore we hypothesize that SlSWEET10 is involved in the transport of sucrose from the sieve elements into the fruit parenchyma apoplast. In this work, we have analyzed the effect of variable SWEET10 expression on sugar accumulation and fruit weight using transgenic tomato plants. We have identified the subcellular localization of the SWEET10 protein in fruit, and have compared the expression of SWEET10 and its closest homologs in domesticated tomatoes to their wild relatives. Our results suggest that SlSWEET10 plays an important role in sugar transport during early fruit development, a novel, so far unreported function for SWEET transporters. This research will generate insights into the regulation of fruit development and help identify important genes contributing to crop quality.

My Experience:

Through my time at BTI I have become a more confident researcher. Working independently improved my problem-solving skills and critical thinking, while working together with my lab towards one common project has helped to refine my skills in communication and time management. I felt like I was a member of a wider community of plant biologists whose enthusiasm for their work is infectious and inspiring. Through these experiences I have been able to better define my own research interests and have also been able to speak with Cornell professors about the research being conducted in these areas. I have learned more about life as a graduate student, and the process of applying to Cornell PhD programs. Overall, I believe that this summer has been one of the most transformative and educational in my academic career, and I now look even more forward to pursuing a career in plant biology.