Our objective is to create soybeans resistant to Charcoal Rot (CR), a fungal disease that is a significant problem in Kansas agriculture. CR is the primary Kansas soybean crop disease, costing $50 million annually. Management strategies include crop rotation and irrigation, however neither is ideal. CR infects over 500 plant species, including corn, cotton, alfalfa, sorghum, and sunflower and survives multiple seasons as dormant sclerotia. Irrigation suppresses CR symptoms, allowing plants to survive to harvest, but is expensive, doesn't guarantee crop yield, and encourages root-rot. No CR resistance has been identified so traditional crop-crossing from a hardier wild population is not possible. To get CR resistant soybeans, transgenes are needed.
We are developing transgenic soybeans designed to overexpress a soybean glucanase enzyme (naturally expressed at low levels) that is involved in cell wall development. This enzyme is encoded by the gene Brassinosteroid On Zurek One (BOZO). The protein has shown both antibiotic and antifungal properties in inhibiting the growth of gram negative bacteria and CR, respectively. We believe it plays a role in the development of bacterial and fungal cell walls. Some fungal and oomycete plant pathogens display resistance via specific glucanase inhibitors but no such resistance was seen to our protein from CR.
The first attempt at transforming soybeans with our construct was unsuccessful. A literature review has investigated teh ideal gene construct and promoter sequence to use for optimal BOZO expression in soybean plants. Due to the role of glucanase proteins in cell wall development, it is critical to develop a system with manageable expression to ensure that there is negligible structural or developmental mutations.
The alcAmin 35S promoter system is an ethanol-induced platform and shows the greatest potential for successful transformation of BOZO. The plant transformation facilities at Iowa State University have promising history generating transgenic soybeans using Agrobacterium-mediated transformations with the pTF102 plasmid.
The current research is a preliminary study for future work regarding protein levels and identifying any negative side-effects overexpression of BOZO has on soybean development. If this research is successful we will not have designed a soybean line resistant to charcoal. Root infection, but may identify a natural antibiotic and antifungal agent that could be used in human application.