The Translation Elongation Factor eEF-1Bβ1 Is Involved in Cell Wall Biosynthesis and Plant Development in <em>Arabidopsis thaliana</em>

<div><p>The eukaryotic translation elongation factor eEF-1Bβ1 (EF1Bβ) is a guanine nucleotide exchange factor that plays an important role in translation elongation. In this study, we show that the EF1Bβ protein is localized in the plasma membrane and cytoplasm, and that the transcripts should be expressed in most tissue types in seedlings. Sectioning of the inflorescence stem revealed that EF1Bβ predominantly localizes to the xylem vessels and in the interfascicular cambium. <em>EF1Bβ</em> gene silencing in <em>efβ</em> caused a dwarf phenotype with 38% and 20% reduction in total lignin and crystalline cellulose, respectively. This loss-of-function mutant also had a lower S/G lignin monomer ratio relative to wild type plants, but no changes were detected in a gain-of-function mutant transformed with the <em>EF1Bβ</em> gene. Histochemical analysis showed a reduced vascular apparatus, including smaller xylem vessels in the inflorescence stem of the loss-of-function mutant. Over-expression of <em>EF1Bβ</em> in an <em>eli1</em> mutant background restored a WT phenotype and abolished ectopic lignin deposition as well as cell expansion defects in the mutant. Taken together, these data strongly suggest a role for EF1Bβ in plant development and cell wall formation in Arabidopsis.</p> </div

Total lignin and crystalline cellulose in inflorescence stems of EFβOX and <i>efβ</i> plants.

<p>Lignin is shown relative to that of the WT (A). Cellulose is expressed as µg cellulose mg⁻¹ dry CWM (B). Data presented are means ± SD for three independent experiments, each replicated three times. * and ** indicate significant differences at <i>P</i>≤0.05 and 0.01, respectively.</p

Additional file 17: of Transcriptome profiling of Brassica napus stem sections in relation to differences in lignin content

Table S11. Selected non-TF genes for lignin validation using Arabidopsis mutants. (DOCX 17 kb

Additional file 3: of Transcriptome profiling of Brassica napus stem sections in relation to differences in lignin content

Table S2A. Differential expression of DH1 vs YN1 less than point 5 (microarray). (XLSX 496 kb

Confocal images showing localization of EF1Bβ-YFP (A and E) in Arabidopsis root tip cells plasmolyzed with 0.75 M sorbitol.

<p>SynaptoRed (SR) was used as a plasma membrane marker (B and F). Panels C and G are the merged images of the YFP and SR channels and D and H show the DIC images. Lower panels (E-H) show a close-up of root tip cells. Bars  =  10 µm. Arrowheads (A and E) highlight the YFP localization in the cell periphery.</p

Additional file 1: of Transcriptome profiling of Brassica napus stem sections in relation to differences in lignin content

Table S1A. Differential expression of DH1 vs DH4 less than point 5 (microarray). (XLSX 360 kb

Additional file 2: of Transcriptome profiling of Brassica napus stem sections in relation to differences in lignin content

Table S1B. Differential expression of DH1 vs DH4 greater than 2 (microarray). (XLSX 442 kb

Additional file 16: of Transcriptome profiling of Brassica napus stem sections in relation to differences in lignin content

Table S10. Targeted transcription factors selected for lignin validation using Arabidopsis mutants. (DOCX 25 kb

<i>EF1Bβ</i> expression in inflorescence stem of WT and <i>efβ</i> (A), and of WT and EFβOX (B).

<p>Data represent mean transcript abundance ± SD relative to <i>EF1α</i> and <i>elF4A1</i> from three independent experiments each replicated three times. ** indicates significant difference at <i>P</i> ≤ 0.01.</p

Phenotypes of Arabidopsis wild type, <i>efβ and</i> EFβOX-complemented plants.

<p>Complemented mutant plant was transformed with a <i>35S::EF1Bβ cDNA.</i></p