SBIR-STTR Award

Bacterial Spot is a major disease issue for tomato cultivation in the United States and around the world particularly in warm and humid environments. There are currently no commercial varieties of tomatoes with resistance to this disease and farmers typically rely on expensive and only partially effective chemical controls. We recently identified several immune receptor genes involved in resistance to Xanthomonas the causative bacterial pathogen of this disease. So far we demonstrated that one of these genes named Roq1 confers resistance to Xanthomonas when expressed in tomato. We believe two additional genes named Zar1 and Jim2 will also confer resistance to this pathogen. In the proposed work Zar1 and Jim2 will be expressed in tomato to determine if these genes are sufficient to confer resistance to Xanthomonas. To facilitate commercialization we will use a precise gene delivery system to generate tomato lines with only the desired resistance traits. These "cisgenic" lines won't have no antibiotic resistance makers 35S promoters T-DNAborders or other foreign DNA elements thereby reducing regulatory and market acceptance concerns. In addition to Bacterial Spot we recently showed that Roq1 can confer resistance to Bacterial Speck caused by Pseudomonas and we have preliminary data indicated that these traits will work against some strains of Ralstonia solanacearum another important pathogen of tomato. This work will demonstrate the efficacy of these traits and will result in the generation of tomato variety with durable resistance to Xanthomonas Pseudomonas and Ralstonia.

Bacterial spot is a major problem for field grown fresh market tomato cultivation in the UnitedStates. Chemical controls are only partially effective add extra expense for tomato growers andcan be harmful to the environment. Breeders have worked for many years to develop a tomatovariety with resistance to this disease but have so far been unsuccessful. We identified threenaturally occurring plant immune receptor genes from wild tomato relatives which mediateimmunity to Xanthomonas the causative agent of bacterial spot. These immune receptors detectwhen an invading bacterial pathogen is attacking the plant and activate endogenous defensepathways to prevent disease.We will use these immune receptor genes to develop a commercial tomato variety that is immune tobacterial spot. We developed a gene delivery system that allows us to make precise gene insertionsinto the tomato genome. We will use this method to generate tomato plants that contain only thedesired plant immune receptor genes and don't have any non-plant DNA thereby minimizingconsumer acceptance and regulatory concerns. In addition to strong resistance against bacterialspot the tomatoes will also be immune to bacterial speck and bacterial wilt which are caused by therelated bacterial pathogens Pseudomonas syringae and Ralstonia solanacearum. This technologywill deliver up to $100 million in annual benefit to the US tomato industry while providingconsumers with cheaper higher quality tomatoes and improving the environmental sustainability oftomato cultivation.