Characterization of flagella genes of Agrobacterium tumefaciens, and the effect of a bald strain on virulence

Abstract

Because the 54 promoter is associated with genes regulated by physiological changes in various bacteria, the flaC gene might be similarly regulated in response to A. tumefaciens responding to host plant stimuli. Virulence studies showed that the bald strain was consistently reduced in virulence below that of the parental wild-type strain by at least 38%. The difference is statistically significant and suggests that the flagella may play a role in facilitating virulence.

Definition of a Consensus DNA-binding Site for PecS, a Global Regulator of Virulence Gene Expression in Erwinia chrysanthemi and Identification of New Members of the PecS Regulon

“…In plant pathogens, motility seems to play a role predominantly in the early phases of infection, mediated by chemotaxis and adherence through flagella. Generally, nonflagellate mutants have a significantly reduced capacity to initiate an infection (35,36). Thus, it is tempting to speculate that PecS regulates critical genetic determinants that are required for adaptation to the plant environment as well as for the colonization of the host tissues.…”

“…The proteins encoded by fliE and fliFGHIJKLMNOPQR operons are involved in the biogenesis of the flagellar hook-basal body complex, which forms a flagellum export channel anchored within the bacterial membrane (34). Interestingly, the flagellum has been associated with a bacterial virulence factor because a perturbation of its synthesis results in a reduction of the pathogenic power of both animal and plant pathogenic bacteria (35,36).…”

The pair of bacteriophytochromes from Agrobacterium tumefaciens are histidine kinases with opposing photobiological properties

“…In a similar manner, it is also possible that A. tumefaciens uses this ratio as a way to detect its location within the soil strata. For example by adjusting its motility with the R͞FR ratio, Agrobacterium could optimize its position within the rhizosphere to promote contact with a host root (21). It is possible that other bacteria also use such an opposing pair of BphPs.…”

GABA controls the level of quorum-sensing signal in Agrobacterium tumefaciens

“…Tumors emerged around the leaf disk, and the level of virulence of A. tumefaciens was estimated according to the following symptom scale: 0, no tumors; 1, fewer than five tumors; 2, more than five tumors, but none contiguous; 3, contiguous tumors; 4, contiguous and large tumors, which modify the shape of the disk. Virulence assays were also conducted on stems of the 12-week-old tobacco plants, which were incised with a scalpel (incision of 4 cm in length) and inoculated with A. tumefaciens (10 8 colony-forming units per incision); the weights of tumors were measured 5 weeks after bacterial inoculation, as previously described (31). Unwounded and wounded stems of 6-week-old Solanum lycopersicum L. cv.…”