Crop yield in rice (Joon Seob Eom)
With a world production of ≈480 million tons per year, rice is among the three most important crop plants. Our work focuses on two topics: allocation of soluble sugars as key determinants of yield potential, and pathogen resistance as a key aspect of actual yield as well as food security.
What is the path of sucrose from leaf mesophyll to the seed storage cells
Since sucrose is quantitatively the most prominent osmolyte in the phloem sap (the conduits that transport nutrients from leaves to roots and seeds) of many plants, the transporters responsible for phloem loading and unloading of sucrose play critical roles for crop yield potential. We identified SWEET sucrose efflux systems and SUT sucrose proton symporters as essential transporters for both loading and unloading in a variety of plant species. We are currently systematically mapping out the pathways for phloem loading and seed filling in Arabidopsis, rice, maize and other crops. Plants have unique cell-cell connections, plasmodesmata, which are supposed to be able to mediate diffusion of sucrose. We surmise that a detailed understanding of the translocation pathways will lay the basis for engineering crop yield.
What is the role of sugar transporters in pathogen susceptibility?
Pathogens infect plants in order to gain access to host nutrients needed for effective reproduction. We found that SWEETs a targeted by many pathogens, and that we can engineer resistance by blocking activation of the transporters by the pathogen. In a large collaboration, funded in part by the Bill and Melinda Gates Foundation, we develop plants that are resistant against pathogens. Beside the biotechnological aspects, we also study the mechanisms that cause to susceptibility.