[Gene deletion and functional analysis of the EAL domain protein vieAxoo in Xanthomonas oryzae pv. oryzae].

Objective: To better reveal the functions of key members involved in cyclic di-GMP signal metabolism pathways in the bacterial blight pathogen of rice Xanthomonas oryzae pv. oryzae (Xoo).

Methods: vieAxoo (PXO 04753), a gene putatively encoding the EAL domain proteins was investigated by gene deletion mutation using the marker exchange, complementation and phenotypic analysis.

Result: The sequence of vieAxoo cloned from genomic DNA of the wild-type strain PXO99(A) was found to be highly conserved in plant-pathogenic Xanthomonas spp. VieAxoo was structurally featured with EAL and REC domains. No significant changes in virulence to rice, EPS production and flagellar motility were found in deltavieAxoo compared to PXO99(A), whereas remarkable changes in induction of hypersensitive responses (HR) in tobacco and biofilm formation were observed.

Conclusion: VieAxoo might function as an important reponse regulator in cyclic di-GMP signaling and regulation of bacterial induction of HR and biofilm formation of Xoo.