Quorum-sensing regulation of a hypersensitive response induced by Agrobactrium vitis

• Author(s): Burr, Thomas; Hao, G.; Zhang, Hongsheng;
• Abstract: A luxR homolog in A. vitis strain F2/5 was recently shown to be associated with a hypersensitive response on tobacco and necrogenesis on grape. A second luxR-like gene (R1320) has now been identified by Tn5 mutagenesis. The insertion in this ORF results in loss of the HR and a reduction in grape necrosis. R1320 was compared with other LuxR transcriptional regulators from related species within Rhizobiaceae. TLC-biosensor generated profiles of N-acyl-homoserine lactone autoinducers suggest that there are no differences between the R1320 mutant and F2/5. Eleven ORFs within a region of about 14kb flanking the Tn5 insertion were identified and aligned with homologous genes from A. tumefaciens strain C58 showing high identity to corresponding genes in A. tumefaciens strain C58. The R1320 mutant was fully complemented mutant with a corresponding cosmid clone (approximately 35kb). When the luxR-like gene alone was cloned and used in complementation experiments, the corresponding phenotypes were not restored. Site-directed mutagenesis was performed to check whether other candidate genes that may be related to hypersensitive response and necrosis.
• Publication Date: Jun 2003
• Journal: Phytopathology