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Phenolic compounds and expression of 4CL genes in silver birch clones and Pt4CL1a lines.

Sutela S, Hahl T, Tiimonen H, Aronen T, Ylioja T, Laakso T, Saranpää P, Chiang V, Julkunen-Tiitto R, Häggman H - PLoS ONE (2014)

Bottom Line: However, considerable variation was found in the transcript levels of silver birch 4CLs as well as in the concentration of phenolic compounds among the transgenic lines and non-transgenic clones.The results indicate that by reducing the Bp4CL1 transcript levels lignin composition could be modified.However, the alterations found among the Pt4CL1a lines and the non-transgenic clones were within the natural variation of silver birches, as shown in the present study by the clonal differences in the transcripts levels of 4CL genes, soluble phenolic compounds and condensed tannins.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Oulu, Oulu, Finland.

ABSTRACT
A small multigene family encodes 4-coumarate:CoA ligases (4CLs) catalyzing the CoA ligation of hydroxycinnamic acids, a branch point step directing metabolites to a flavonoid or monolignol pathway. In the present study, we examined the effect of antisense Populus tremuloides 4CL (Pt4CL1) to the lignin and soluble phenolic compound composition of silver birch (Betula pendula) Pt4CL1a lines in comparison with non-transgenic silver birch clones. The endogenous expression of silver birch 4CL genes was recorded in the stems and leaves and also in leaves that were mechanically injured. In one of the transgenic Pt4CL1a lines, the ratio of syringyl (S) and guaiacyl (G) lignin units was increased. Moreover, the transcript levels of putative silver birch 4CL gene (Bp4CL1) were reduced and contents of cinnamic acid derivatives altered. In the other two Pt4CL1a lines changes were detected in the level of individual phenolic compounds. However, considerable variation was found in the transcript levels of silver birch 4CLs as well as in the concentration of phenolic compounds among the transgenic lines and non-transgenic clones. Wounding induced the expression of Bp4CL1 and Bp4CL2 in leaves in all clones and transgenic lines, whereas the transcript levels of Bp4CL3 and Bp4CL4 remained unchanged. Moreover, minor changes were detected in the concentrations of phenolic compounds caused by wounding. As an overall trend the wounding decreased the flavonoid content in silver birches and increased the content of soluble condensed tannins. The results indicate that by reducing the Bp4CL1 transcript levels lignin composition could be modified. However, the alterations found among the Pt4CL1a lines and the non-transgenic clones were within the natural variation of silver birches, as shown in the present study by the clonal differences in the transcripts levels of 4CL genes, soluble phenolic compounds and condensed tannins.

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Relative expression of Bp4CL1-4 genes in mechanically wounded silver birch (Betula pendula) leaves.The Bp4CL1 (A, B) and Bp4CL2 (C, D) expression in leaves collected immediately (w0) and 1, 3, 12, 24, 48, and 162 h after mechanical wounding of clones A and R and transgenic lines A1 and A5 (A, C) and clones E5382 and E5396 and transgenic lines E5382 and E5396 (B, D). Values represent mean ± SE calculated using the mean of control leaves as normalizer within each line/clone and PP2A as reference.
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pone-0114434-g002: Relative expression of Bp4CL1-4 genes in mechanically wounded silver birch (Betula pendula) leaves.The Bp4CL1 (A, B) and Bp4CL2 (C, D) expression in leaves collected immediately (w0) and 1, 3, 12, 24, 48, and 162 h after mechanical wounding of clones A and R and transgenic lines A1 and A5 (A, C) and clones E5382 and E5396 and transgenic lines E5382 and E5396 (B, D). Values represent mean ± SE calculated using the mean of control leaves as normalizer within each line/clone and PP2A as reference.

Mentions: The Bp4CL1 expression peaked 3 h after wounding in leaves of all studied clones and lines (Fig. 2A, B, S15 Figure in S1 File). After 24 h, the clone R showed clear induction in the Bp4CL1 transcript levels, whereas the levels were somewhat increased in other clones and lines. In clones R and A, as well as in lines A1 and A5, the expression of Bp4CL2 was highest in samples collected 24 h after the wounding (Fig. 2C, S15 Figure in S1 File). In clones E5382 and E5396 and in line E5396/4 the relative expression of Bp4CL2 peaked at 12 h after wounding and in the case of clones E5396 and E5382 it stayed at higher level also 24 h after treatment (Fig. 2D). The Bp4CL3 and Bp4CL4 transcript levels did not respond to the wounding (S16 Figure in S1 File).


Phenolic compounds and expression of 4CL genes in silver birch clones and Pt4CL1a lines.

Sutela S, Hahl T, Tiimonen H, Aronen T, Ylioja T, Laakso T, Saranpää P, Chiang V, Julkunen-Tiitto R, Häggman H - PLoS ONE (2014)

Relative expression of Bp4CL1-4 genes in mechanically wounded silver birch (Betula pendula) leaves.The Bp4CL1 (A, B) and Bp4CL2 (C, D) expression in leaves collected immediately (w0) and 1, 3, 12, 24, 48, and 162 h after mechanical wounding of clones A and R and transgenic lines A1 and A5 (A, C) and clones E5382 and E5396 and transgenic lines E5382 and E5396 (B, D). Values represent mean ± SE calculated using the mean of control leaves as normalizer within each line/clone and PP2A as reference.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263613&req=5

pone-0114434-g002: Relative expression of Bp4CL1-4 genes in mechanically wounded silver birch (Betula pendula) leaves.The Bp4CL1 (A, B) and Bp4CL2 (C, D) expression in leaves collected immediately (w0) and 1, 3, 12, 24, 48, and 162 h after mechanical wounding of clones A and R and transgenic lines A1 and A5 (A, C) and clones E5382 and E5396 and transgenic lines E5382 and E5396 (B, D). Values represent mean ± SE calculated using the mean of control leaves as normalizer within each line/clone and PP2A as reference.
Mentions: The Bp4CL1 expression peaked 3 h after wounding in leaves of all studied clones and lines (Fig. 2A, B, S15 Figure in S1 File). After 24 h, the clone R showed clear induction in the Bp4CL1 transcript levels, whereas the levels were somewhat increased in other clones and lines. In clones R and A, as well as in lines A1 and A5, the expression of Bp4CL2 was highest in samples collected 24 h after the wounding (Fig. 2C, S15 Figure in S1 File). In clones E5382 and E5396 and in line E5396/4 the relative expression of Bp4CL2 peaked at 12 h after wounding and in the case of clones E5396 and E5382 it stayed at higher level also 24 h after treatment (Fig. 2D). The Bp4CL3 and Bp4CL4 transcript levels did not respond to the wounding (S16 Figure in S1 File).

Bottom Line: However, considerable variation was found in the transcript levels of silver birch 4CLs as well as in the concentration of phenolic compounds among the transgenic lines and non-transgenic clones.The results indicate that by reducing the Bp4CL1 transcript levels lignin composition could be modified.However, the alterations found among the Pt4CL1a lines and the non-transgenic clones were within the natural variation of silver birches, as shown in the present study by the clonal differences in the transcripts levels of 4CL genes, soluble phenolic compounds and condensed tannins.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Oulu, Oulu, Finland.

ABSTRACT
A small multigene family encodes 4-coumarate:CoA ligases (4CLs) catalyzing the CoA ligation of hydroxycinnamic acids, a branch point step directing metabolites to a flavonoid or monolignol pathway. In the present study, we examined the effect of antisense Populus tremuloides 4CL (Pt4CL1) to the lignin and soluble phenolic compound composition of silver birch (Betula pendula) Pt4CL1a lines in comparison with non-transgenic silver birch clones. The endogenous expression of silver birch 4CL genes was recorded in the stems and leaves and also in leaves that were mechanically injured. In one of the transgenic Pt4CL1a lines, the ratio of syringyl (S) and guaiacyl (G) lignin units was increased. Moreover, the transcript levels of putative silver birch 4CL gene (Bp4CL1) were reduced and contents of cinnamic acid derivatives altered. In the other two Pt4CL1a lines changes were detected in the level of individual phenolic compounds. However, considerable variation was found in the transcript levels of silver birch 4CLs as well as in the concentration of phenolic compounds among the transgenic lines and non-transgenic clones. Wounding induced the expression of Bp4CL1 and Bp4CL2 in leaves in all clones and transgenic lines, whereas the transcript levels of Bp4CL3 and Bp4CL4 remained unchanged. Moreover, minor changes were detected in the concentrations of phenolic compounds caused by wounding. As an overall trend the wounding decreased the flavonoid content in silver birches and increased the content of soluble condensed tannins. The results indicate that by reducing the Bp4CL1 transcript levels lignin composition could be modified. However, the alterations found among the Pt4CL1a lines and the non-transgenic clones were within the natural variation of silver birches, as shown in the present study by the clonal differences in the transcripts levels of 4CL genes, soluble phenolic compounds and condensed tannins.

Show MeSH
Related in: MedlinePlus