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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

TFs regulated by YE or MJ in M. truncatula cell suspension cultures. Venn diagrams showing the numbers of transcription factors induced by YE or MJ at 2 h (A) and 24 h (B) of treatment. Up- (C) and down-regulated (D) transcription factors are classified according to [23].
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Figure 1: TFs regulated by YE or MJ in M. truncatula cell suspension cultures. Venn diagrams showing the numbers of transcription factors induced by YE or MJ at 2 h (A) and 24 h (B) of treatment. Up- (C) and down-regulated (D) transcription factors are classified according to [23].

Mentions: More than 1,350 TFs have been identified in the M. truncatula genome to date [23], and new classes of plant TFs are still being discovered [23,24]. To provide a global analysis of TFs that are transcriptionally regulated by YE or MJ, we performed transcript profiling using Affymetrix Medicago arrays to compare 2 h and 24 h elicited samples to corresponding controls. The array contains over 61,200 probe sets: 32,167 M. truncatula EST/mRNA-based and chloroplast gene-based probe sets; 18,733 M. truncatula IMGAG and phase 2/3 BAC prediction-based probe sets; 1,896 M. sativa EST/mRNA-based probe sets; and 8,305 Sinorhizobium meliloti gene prediction-based probe sets. Genes encoding 502 TFs were differentially expressed in M. truncatula cell suspension cultures treated with YE or MJ (Additional file 1). However, the pattern of activation of TFs by YE or MJ was different (Figure 1A, B). After 2 h of treatment, 343 TFs were up-regulated by YE, 191 by MJ, and 125 by both (Figure 1A). At 24 h, the differences between the two treatments were greater; the number of TFs up-regulated by YE dropped, but MJ up-regulated TFs increased and only 19 were up-regulated by both treatments (Figure 1B).


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

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

TFs regulated by YE or MJ in M. truncatula cell suspension cultures. Venn diagrams showing the numbers of transcription factors induced by YE or MJ at 2 h (A) and 24 h (B) of treatment. Up- (C) and down-regulated (D) transcription factors are classified according to [23].
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: TFs regulated by YE or MJ in M. truncatula cell suspension cultures. Venn diagrams showing the numbers of transcription factors induced by YE or MJ at 2 h (A) and 24 h (B) of treatment. Up- (C) and down-regulated (D) transcription factors are classified according to [23].
Mentions: More than 1,350 TFs have been identified in the M. truncatula genome to date [23], and new classes of plant TFs are still being discovered [23,24]. To provide a global analysis of TFs that are transcriptionally regulated by YE or MJ, we performed transcript profiling using Affymetrix Medicago arrays to compare 2 h and 24 h elicited samples to corresponding controls. The array contains over 61,200 probe sets: 32,167 M. truncatula EST/mRNA-based and chloroplast gene-based probe sets; 18,733 M. truncatula IMGAG and phase 2/3 BAC prediction-based probe sets; 1,896 M. sativa EST/mRNA-based probe sets; and 8,305 Sinorhizobium meliloti gene prediction-based probe sets. Genes encoding 502 TFs were differentially expressed in M. truncatula cell suspension cultures treated with YE or MJ (Additional file 1). However, the pattern of activation of TFs by YE or MJ was different (Figure 1A, B). After 2 h of treatment, 343 TFs were up-regulated by YE, 191 by MJ, and 125 by both (Figure 1A). At 24 h, the differences between the two treatments were greater; the number of TFs up-regulated by YE dropped, but MJ up-regulated TFs increased and only 19 were up-regulated by both treatments (Figure 1B).

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