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Elicitor-induced transcription factors for metabolic reprogramming of secondary metabolism in Medicago truncatula.

Naoumkina MA, He X, Dixon RA - BMC Plant Biol. (2008)

Bottom Line: Levels of soluble and wall bound phenolic compounds and lignin were increased in all cases.WRKY W109669 also induced tobacco endo-1,3-beta-glucanase (NtPR2) and enhanced the systemic defense response to tobacco mosaic virus in transgenic tobacco plants.These results confirm that Medicago WRKY TFs have broad roles in orchestrating metabolic responses to biotic stress, and that they also represent potentially valuable reagents for engineering metabolic changes that impact pathogen resistance.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA. manaoumkina@noble.org

ABSTRACT

Background: Exposure of Medicago truncatula cell suspension cultures to pathogen or wound signals leads to accumulation of various classes of flavonoid and/or triterpene defense molecules, orchestrated via a complex signalling network in which transcription factors (TFs) are essential components.

Results: In this study, we analyzed TFs responding to yeast elicitor (YE) or methyl jasmonate (MJ). From 502 differentially expressed TFs, WRKY and AP2/EREBP gene families were over-represented among YE-induced genes whereas Basic Helix-Loop-Helix (bHLH) family members were more over-represented among the MJ-induced genes. Jasmonate ZIM-domain (JAZ) transcriptional regulators were highly induced by MJ treatment. To investigate potential involvement of WRKY TFs in signalling, we expressed four Medicago WRKY genes in tobacco. Levels of soluble and wall bound phenolic compounds and lignin were increased in all cases. WRKY W109669 also induced tobacco endo-1,3-beta-glucanase (NtPR2) and enhanced the systemic defense response to tobacco mosaic virus in transgenic tobacco plants.

Conclusion: These results confirm that Medicago WRKY TFs have broad roles in orchestrating metabolic responses to biotic stress, and that they also represent potentially valuable reagents for engineering metabolic changes that impact pathogen resistance.

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Related in: MedlinePlus

Expression of WRKY transcription factors in M. truncatula cell cultures. A, induction of WRKYs by YE as revealed by oligonucleotide array analysis. The double apostrophes represent minutes and the single apostrophes represent hours. B, WRKY transcript levels in YE and MJ treated cells determined by Affymetrix array analysis. C, Detailed time course for WRKY gene transcript levels in response to YE, as determined by RT-PCR. Actin is shown as loading control.
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Figure 2: Expression of WRKY transcription factors in M. truncatula cell cultures. A, induction of WRKYs by YE as revealed by oligonucleotide array analysis. The double apostrophes represent minutes and the single apostrophes represent hours. B, WRKY transcript levels in YE and MJ treated cells determined by Affymetrix array analysis. C, Detailed time course for WRKY gene transcript levels in response to YE, as determined by RT-PCR. Actin is shown as loading control.

Mentions: Selection of WRKY TFs was based on the pattern of their transcriptional induction by YE. The heat map in Figure 2A shows detailed induction kinetics of seven WRKY genes induced by YE as revealed by oligonucleotide array analysis. This approach gives lower reproducibility than the Affymetrix arrays, but allows for analysis of more time points due to its much lower cost. Many of the WRKY genes were rapidly induced by as early as 15 min after treatment, and their transcript levels were reduced after 2 h post-elicitation. Using the more sensitive Affymetrix microarray technique, the transcript levels of the WRKY genes were quantified at 2 h and 24 h after YE or MJ treatment (Figure 2B). The most strongly expressed WRKY, corresponding to tentative consensus (TC) 109669, was up-regulated 594-fold in response to YE. The expression kinetics of several of the WRKY genes, including the one down-regulated by YE, were confirmed by non-quantitative RT-PCR (Figure 2C) and the results further validated by semi-quantitative RT-PCR (Additional file 4).


Elicitor-induced transcription factors for metabolic reprogramming of secondary metabolism in Medicago truncatula.

Naoumkina MA, He X, Dixon RA - BMC Plant Biol. (2008)

Expression of WRKY transcription factors in M. truncatula cell cultures. A, induction of WRKYs by YE as revealed by oligonucleotide array analysis. The double apostrophes represent minutes and the single apostrophes represent hours. B, WRKY transcript levels in YE and MJ treated cells determined by Affymetrix array analysis. C, Detailed time course for WRKY gene transcript levels in response to YE, as determined by RT-PCR. Actin is shown as loading control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2628384&req=5

Figure 2: Expression of WRKY transcription factors in M. truncatula cell cultures. A, induction of WRKYs by YE as revealed by oligonucleotide array analysis. The double apostrophes represent minutes and the single apostrophes represent hours. B, WRKY transcript levels in YE and MJ treated cells determined by Affymetrix array analysis. C, Detailed time course for WRKY gene transcript levels in response to YE, as determined by RT-PCR. Actin is shown as loading control.
Mentions: Selection of WRKY TFs was based on the pattern of their transcriptional induction by YE. The heat map in Figure 2A shows detailed induction kinetics of seven WRKY genes induced by YE as revealed by oligonucleotide array analysis. This approach gives lower reproducibility than the Affymetrix arrays, but allows for analysis of more time points due to its much lower cost. Many of the WRKY genes were rapidly induced by as early as 15 min after treatment, and their transcript levels were reduced after 2 h post-elicitation. Using the more sensitive Affymetrix microarray technique, the transcript levels of the WRKY genes were quantified at 2 h and 24 h after YE or MJ treatment (Figure 2B). The most strongly expressed WRKY, corresponding to tentative consensus (TC) 109669, was up-regulated 594-fold in response to YE. The expression kinetics of several of the WRKY genes, including the one down-regulated by YE, were confirmed by non-quantitative RT-PCR (Figure 2C) and the results further validated by semi-quantitative RT-PCR (Additional file 4).

Bottom Line: Levels of soluble and wall bound phenolic compounds and lignin were increased in all cases.WRKY W109669 also induced tobacco endo-1,3-beta-glucanase (NtPR2) and enhanced the systemic defense response to tobacco mosaic virus in transgenic tobacco plants.These results confirm that Medicago WRKY TFs have broad roles in orchestrating metabolic responses to biotic stress, and that they also represent potentially valuable reagents for engineering metabolic changes that impact pathogen resistance.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA. manaoumkina@noble.org

ABSTRACT

Background: Exposure of Medicago truncatula cell suspension cultures to pathogen or wound signals leads to accumulation of various classes of flavonoid and/or triterpene defense molecules, orchestrated via a complex signalling network in which transcription factors (TFs) are essential components.

Results: In this study, we analyzed TFs responding to yeast elicitor (YE) or methyl jasmonate (MJ). From 502 differentially expressed TFs, WRKY and AP2/EREBP gene families were over-represented among YE-induced genes whereas Basic Helix-Loop-Helix (bHLH) family members were more over-represented among the MJ-induced genes. Jasmonate ZIM-domain (JAZ) transcriptional regulators were highly induced by MJ treatment. To investigate potential involvement of WRKY TFs in signalling, we expressed four Medicago WRKY genes in tobacco. Levels of soluble and wall bound phenolic compounds and lignin were increased in all cases. WRKY W109669 also induced tobacco endo-1,3-beta-glucanase (NtPR2) and enhanced the systemic defense response to tobacco mosaic virus in transgenic tobacco plants.

Conclusion: These results confirm that Medicago WRKY TFs have broad roles in orchestrating metabolic responses to biotic stress, and that they also represent potentially valuable reagents for engineering metabolic changes that impact pathogen resistance.

Show MeSH
Related in: MedlinePlus