Cotton Bacterial Blight: The case of a (re)emergent disease
A. PHILLIPS (1), M. Wilson (2), A. Vijayaraghavan (2), J. Burke (2), I. Bunn (3), K. Veley (2), R. Bart (2) (1) Donald Danforth Plant Science Center and Washington University in Saint Louis, U.S.A.; (2) Donald Danforth Plant Science Center, U.S.A.; (3) Harvard University, U.S.A.

Cotton Bacterial Blight (CBB) is a disease that negatively affects cotton yield worldwide. Since 2011, the disease has re-emerged as an agronomic problem in the southern United States, the cause of which is unknown. Xanthomonas citri pv. malvacearum (Xcm), a gram negative proteobacterium, promotes the disease by injecting type three effector (T3E) proteins into plant cells. Historically, isolates were classified into races according to their ability to elicit disease symptoms on a panel of cotton varieties. However, many varieties in this panel are no longer easily obtainable and some interactions are environmentally influenced, further complicating race designations. Comparative genomics among isolates collected from the southern US as well as historical isolates identifies conserved and variable T3E protein repertoires present in each strain. Further, PacBio sequencing and western blot analysis of two Xcm strains reveals a difference in the profiles of Transcription Activator-Like (TAL) effectors. RNAseq analysis demonstrates that these strains up-regulate different susceptibility genes in host plants, which could collectively be targeted with genome editing technologies to achieve tolerance to diverse strains of Xcm. Collectively, these data allow hypothesis building regarding the emergence of this disease, provide molecular explanations for the observed host-pathogen specificity, and point towards potential strategies to develop durable resistance against CBB.

Abstract Number: P11-373
Session Type: Poster