2015 Meeting | Differential host specificity of the two related pathovars Pantoea agglomerans pvs. gypsophilae and betae as expressed by type III effectors

Poster Session: Molecular and Cellular Plant-Microbe Interactions - Molecular Aspects of Effectors and their Host Targets

682-P

Differential host specificity of the two related pathovars Pantoea agglomerans pvs. gypsophilae and betae as expressed by type III effectors.
M. Gershovitz (1), G. Nissan (2), L. Chalupowicz (3), M. Morozov (4), S. Manulis-Sasson (5), G. Sessa (2), T. Pupko (2), I. BARASH (6)
(1) Tel Aviv University, Trl Aviv, Israel; (2) Tel Aviv University, Tel Aviv, Israel; (3) ARO, The Volcani Center, Bet Dagan, Israel; (4) Tel Aviv university, Tel Aviv, Israel; (5) ARO, The Volcani, Center, Bet Dagan, Israel; (6) Tel Aviv Univ, Tel Aviv,

Pantoea agglomerans (Pa), a widespread epiphyte and commensal bacterium, has evolved into a host-specific tumorigenic pathogen by acquiring a plasmid containing a pathogenicity island. Two related pathovars have been investigated: Pa pv. gypsophilae (Pag), which elicits galls on gypsophila and hypersensitive response (HR) on beet and Pa pv. betae (Pab), which elicits galls on both beet and gypsophila. Pathogenicity of Pag and Pab depends on a type III secretion system (T3SS), which resides on the pathogenicity plasmids pPATH_Pag and pPATH_Pab. Three T3SS effectors (T3Es), HsvG, HsvB and PthG, had been previously implicated in the differential host specificity of Pag and Pab. Here we aimed to identify all the T3Es encoded by the two pathovars and to investigate their potential role in host specificity. To this end, we first obtained draft genome sequences of both Pag (824-1) and Pab (4188). Then a machine-learning approach was applied for predicting encoded T3Es. A tanslocation assay into beet roots, based on features of pthG, was constructed and applied for validation of predicted T3Es. It was found that Pag and Pab have a genome size of 5.01and 5.02 Mb, 4598 and 4599 ORFs and a GC content of 54.8% and 54.9%, respectively. Eleven plasmid-borne T3Es are common to both pathovars, whereas 2 and 3 effectors are specific to Pag and Pab, respectively. The possible contribution of specific T3Es to host specificity will be presented