Quantitative measurement of biofilm formation as indicated by absorbance at OD₅₉₀ in <i>Xv</i>.

<p>Quantitative measurement of biofilm formation as indicated by absorbance at OD₅₉₀ in <i>Xv</i>.</p

Quantitative comparison of siderophore production in <i>Xv</i> strains.

<p>Black diamond: wild-type strain <i>Xv</i>17; black square: <i>fur</i> mutation strain fur-m; and black triangle: <i>fur</i> complementation strain fur-c. </p

Effect of <i>fur</i> in <i>Xv</i> virulence on tomato leaves.

<p>Fifty-day-old tomato plants (cv No.4 Zhongshu) were spray inoculated with A) <i>Xv</i>17; B) fur-m; C) fur-c; and D) LB medium (negative control).</p

PCR primers used in this study.

<p>PCR primers used in this study.</p

Bacterial strains and plasmids used in this study.

<p>Bacterial strains and plasmids used in this study.</p

Comparison of siderophore production in <i>Xv</i> strains using the Chrome azurol S assay.

<p>Yellow halos around bacterial colonies indicate siderophore production. <i>Xv</i>17: wild-type <i>Xv</i> strain; fur-m: <i>fur</i> mutation strain of <i>Xv</i> 17; and fur-c: <i>fur</i> complementation strain of fur-m.</p

Effect of <i>fur</i> on biofilm formation (A) and quorum sensing (QS) signals in <i>Xv</i> (B).

<p>Biofilm formation is indicated by the ring formed on the surface of glass test tubes. QS signal expression was indicated by blue halos 12–18 h after each strain was spotted and after incubation on ABM plates at 28°C. A QS assay was used to detect signaling molecules as a blue halo. <i>Xv</i>17: wild-type <i>Xv</i> strain; fur-m: <i>fur</i> mutation strain of <i>Xv</i>17; and fur-c: <i>fur</i> complementation strain of fur-m. Ecc3: <i>E</i>. <i>carotovora</i> subsp. <i>carotovora</i> strain 3 as a positive control for expression of QS signals.</p

Comparison of swimming motility in <i>Xv</i> strains.

<p>Bar heights are the mean diameter of the swimming halos from three replicates ± standard deviation (SD). Different letters above the bars indicate significantly different diameters (<i>P</i> < 0.05) based on Duncan’s multiple range test.</p

Virulence of <i>Xv</i> strains on tomato leaves.

<p>Virulence of <i>Xv</i> strains on tomato leaves.</p