qRT-PCR primer sets used in this study.

<p>qRT-PCR primer sets used in this study.</p

Strains and plasmids used in this study.

<p>Amp^r, Km^r, Tet^r indicate resistance to ampicillin, kanamycin, and tetracycline, respectively; CR, Congo red binding; Floc, flocculation.</p><p>Strains and plasmids used in this study.</p

Plant-root binding abilities of <i>A. brasilense</i> strain.

<p>Colonization of wheat root by Sp7 (1 and 4), Sp7-flcAΔ (2 and 5) and Sp72001 (3 and 6). <i>A</i>. <i>brasilense</i> strains harbor the reporter plasmid pLA-lacZ, containing a constitutively expressed <i>lacZ</i> gene and were stained with X-gal. Sp7 (1, 4) has strong binding ability to wheat roots and can be found all over the root surface; Sp7-flcAΔ (2, 5) and Sp72001 (3, 6) lost the ability to bind to wheat roots and could only be found in lateral root emergence areas. Scale bars indicate 50 µm (group A) and 5 µm (group B) (Magnification ×100 in group A and ×1000 in group B).</p

Differential protein expression in Sp7 and Sp7-flcAΔ analyzed by 2-DE.

<p>The left section shows the normalized expression volume of the spot in wild type (Sp7) and <i>flcA</i> knock out strain (Sp7-flcAΔ) under flocculation conditions; the relative fold change is shown above each column (Nx indicates that relative fold change could not be calculated as the protein was only detected in either Sp7 or Sp7-flcAΔ). The right section is a 3D representation of the area of interest as provided by PDquest software. Arrows indicate spots with relatively higher expression.</p

Differential gene expression in Sp7 and Sp7-flcAΔ under both nutrient and flocculation conditions, analyzed by qRT-PCR.

<p>Transcription levels of <i>atpD, clpP, glnA, livK, nark, narL1, nos</i> and <i>phaA</i> were significantly higher in Sp7-flcAΔ than in Sp7 under flocculation conditions. Transcription levels of <i>cheW, galU</i> and <i>gltA</i> were significantly lower in Sp7-flcAΔ than in Sp7 under flocculation conditions. Transcription levels of <i>ahpC, gloA</i>, <i>lpxC</i> and <i>sodA</i> did not differ significantly in Sp7 and Sp7-flcAΔ under either culture condition. * indicates a significant difference between group means (P<0.05). Data is presented as mean ±SEM, relative to expression of two reference genes, n = 4 biological replicates.</p

Congo-red binding and flocculation of <i>A. brasilense</i> strains.

<p>A. Wild type strain Sp7 (1) and <i>flcA</i> complemented strain Sp7-flcAΔ[pAB2053] (4) form dark red, rough surfaced colonies on NFM agar containing Congo-Red, whereas, Sp7-flcAΔ (2) and Sp72001 (3) form light-red, mucoid, smooth-surfaced colonies on the same medium. B. Flocculation of Sp7 (5) and Sp7-flcAΔ[pAB2053] (8) in flocculation liquid medium; Sp7-flcAΔ (6) and Sp72001 (7) do not flocculate under the same conditions.</p