Table 1.
Bacterial strains, plasmids, and DNA primers used in this study.
Table 2.
Inhibition effects of Rahnella aquatilis HX2 and its derivative strains on growth of Agrobacterium vitis strain K308 and tumor formation on sunflower (Helianthus annuus L. cv. Frankasol) seedlings.
Fig 1.
Characteristics of CsrB of Rahnella aquatilis HX2.
(A) The region of R. aquatilis HX2 with csrB, yjhB and an unknown gene. T1, T2 and T3 are ρ-independent terminators. The mini-Tn5 inserted site in R. aquatilis TR57 was pointed by the triangle. (B) Predicted secondary structure of CsrB at 28°C using the MFOLD program (Zuker et al., 1999; http://www.bioinfo.rpi.edu/applications/mfold/old/rna/form1-2.3.cgi). AGGA and AGGGA motifs are in bold.
Fig 2.
Inhibition zone by Rahnella aquatilis HX2, and its derivatives (R. aquatilis TR61 and R. aquatilis MR61) against Agrobacterium vitis K308.
Fig 3.
Biological control phenotypes of wild-type Rahnella aquatilis HX2 and its derivative strains on sunflower (Helianthus annuus) shoots.
Shoots were inoculated by placing 10-μl drops of bacterial strains (108 CFU ml-1), alone or in equal-number mixtures, at sites in which wounds of 1.0-cm longitudinal incisions were made with a sterile scalpel. Tumor were readily apparent 7 weeks after inoculation. The treatments were SDW alone (Control), Agrobacterium vitis K308 alone (K308), R. aquatilis HX2 plus A. vitis K308 (HX2+K308), and R. aquatilis MR61 plus A. vitis K308 (MR61+K308).
Fig 4.
The ncRNA CsrB is controlled by BarA at the posttranscriptional level in Rahnella aquatilis HX2.
(A) Activation of csrB transcription by BarA. β-galactosidase activities of a transcriptional rsmB-lacZ fusion carried by pMLcsrBlac were determined in the wild type (HX2; circles) and a barA mutant (MR57; squares). (B) The relative level of ncRNA CsrB in Rahnella aquatilis MR57 with or without pRKbarA grown for 12 h in PDB medium. The amount of mRNA was determined by qPCR. Three replicates were used in this experiment. Data with the different letters are significantly different (P<0.05).
Fig 5.
Model of regulation of csrB, BarA/UvrY and PQQ in the pathway of biocontrol activity and in ABS production of R. aquatilis HX2.
The BarA/UvrY and PQQ regulatory cascades of R. aquatilis HX2 were adopted as described [23–25].