Project description:MYB46 functions as a transcriptional switch that turns on the genes necessary for secondary wall biosynthesis. Elucidating the transcriptional regulatory network immediately downstream of MYB46 is crucial to our understanding of the molecular and biochemical processes involved in the biosynthesis and deposition of secondary walls in plants. The transcription factors identified here may include direct activators of secondary wall biosynthesis genes. The current study discovered novel hierarchical relationships among the transcription factors involved in the transcriptional regulation of secondary wall biosynthesis and generated several testable hypotheses. To gain insights into the MYB46-mediated transcriptional regulation, we first established an inducible secondary wall thickening system in Arabidopsis by expressing MYB46 under the control of dexamethasone inducible promoter. Then, we used ATH1 GeneChip microarray to obtain a series of time-course transcriptome profiles with regard to the induction of secondary wall development.
Project description:MYB46 functions as a transcriptional switch that turns on the genes necessary for secondary wall biosynthesis. Elucidating the transcriptional regulatory network immediately downstream of MYB46 is crucial to our understanding of the molecular and biochemical processes involved in the biosynthesis and deposition of secondary walls in plants. The transcription factors identified here may include direct activators of secondary wall biosynthesis genes. The current study discovered novel hierarchical relationships among the transcription factors involved in the transcriptional regulation of secondary wall biosynthesis and generated several testable hypotheses.
Project description:In this study we show that the Arabidopsis transcription factor MYB46, previously described to regulate secondary cell wall biosynthesis in the vascular tissue of the stem, is pivotal for mediating disease susceptibility to the fungal pathogen Botrytis cinerea. We identified MYB46 by its ability to bind to a new cis element located in the 5´ promoter region of the pathogen-induced Ep5C gene which encodes a type III cell wall-bound peroxidase. We present genetic and molecular evidence indicating that MYB46 modulates the magnitude of Ep5C gene induction following pathogenic insults. Moreover, we demonstrate that different myb46 knock-down mutant plants exhibit increased disease resistance to B. cinerea, a phenotype that is accompanied by selective transcriptional reprogramming of a set of genes encoding cell wall proteins and enzymes, of which extracellular type III peroxidases are conspicuous. In essence our results substantiates that defense-related signaling pathways and cell wall integrity are interconnected, and MYB46 likely functions as a disease susceptibility modulator to B. cinerea through the integration of cell wall remodeling and downstream activation of secondary lines of defense.
Project description:In this study we show that the Arabidopsis transcription factor MYB46, previously described to regulate secondary cell wall biosynthesis in the vascular tissue of the stem, is pivotal for mediating disease susceptibility to the fungal pathogen Botrytis cinerea. We identified MYB46 by its ability to bind to a new cis element located in the 5´ promoter region of the pathogen-induced Ep5C gene which encodes a type III cell wall-bound peroxidase. We present genetic and molecular evidence indicating that MYB46 modulates the magnitude of Ep5C gene induction following pathogenic insults. Moreover, we demonstrate that different myb46 knock-down mutant plants exhibit increased disease resistance to B. cinerea, a phenotype that is accompanied by selective transcriptional reprogramming of a set of genes encoding cell wall proteins and enzymes, of which extracellular type III peroxidases are conspicuous. In essence our results substantiates that defense-related signaling pathways and cell wall integrity are interconnected, and MYB46 likely functions as a disease susceptibility modulator to B. cinerea through the integration of cell wall remodeling and downstream activation of secondary lines of defense. 10-15 days-old plants were collected, frozen in liquid nitrogen and stored at -80ºC. Independent replicates from 3 different experiments (separated in time) were used in the analysis. Samples from Col-0 and myb46-2 were compared.
Project description:Using whole genome microarray (Affymetrix ATH1) we studied the transcriptional response of Arabidopsis thaliana to triazolopyrimidine (FirstRate) herbicde that inhibits acetolactate synthase (ALS) enzyme and thus disrupts branched chain amino acid biosynthesis. A number of genes related to amino acid, protein metabolism, growth, regulatory networks, respiratory pathways, stress, defense and secondary metabolism were altered. Keywords: Acetolactate synthase (ALS) inhibiting herbicide stress response
Project description:Using whole genome microarray (Affymetrix ATH1) we studied the transcriptional response of Arabidopsis thaliana to imidazolinone (Arsenal) herbicde that inhibits acetolactate synthase (ALS) enzyme and thus disrupts branched chain amino acid biosynthesis. A number of genes related to amino acid, protein metabolism, growth, regulatory networks, respiratory pathways, stress, defense and secondary metabolism were altered. Keywords: Acetolactate synthase (ALS) inhibiting herbicide stress response
Project description:Using whole genome microarray (Affymetrix ATH1) we studied the transcriptional response of Arabidopsis thaliana to primisulfuron (Beacon) herbicde that inhibits acetolactate synthase (ALS) enzyme and thus disrupts branmched chain amino acid biosynthesis. A number of genes related to amino acid, protein metabolism, growth, regulatory networks, respiratory pathways, stress, defense and secondary metabolism were altered. Keywords: Acetolactate synthase (ALS) inhibiting herbicide stress response
Project description:Secondary wall thickening in the sclerenchyma cells is strictly controlled by a complex network of transcription factors in vascular plant. However, little is known about the epigenetic mechanism regulating secondary cell wall biosynthesis. Genome-wide analysis revealed that the up-regulation of genes involved in secondary wall formation during stem development is largely coordinated by increasing level of H3K4 tri-methylation. In this study, we identified that ARABIDOPSIS HOMOLOG of TRITHORAX1 (ATX1), a H3K4-histone methyltransferase, positively regulates secondary wall deposition mainly through activating the expression of secondary wall NAC master switch genes, SECONDARY WALL-ASSOCIATED NAC DOMAIN PROTEIN1 (SND1) and NAC SECONDARY WALL THICKENING PROMOTING FACTOR1 (NST1).
Project description:Using whole genome microarray (Affymetrix ATH1) we studied the transcriptional response of Arabidopsis thaliana to sulfometuron methyl (oust XP) herbicde that inhibits acetolactate synthase (ALS) enzyme and thus disrupts branmched chain amino acid biosynthesis. A number of genes related to amino acid, protein metabolism, growth, regulatory networks, respiratory pathways, stress, defense and secondary metabolism were altered. Keywords: Acetolactate synthase (ALS) inhibiting herbicide stress response
Project description:Recently, AtC3H14, a CCCH-type zinc finger protein, was identified as one of the direct targets of MYB46, which is known as a master regulator of secondary wall biosynthesis. AtC3H14 and their homologs (i.e., AtC3H15 and PtrC3H14-1 from Arabidopsis and poplar, respectively) are predominantly expressed in the secondary wall forming tissues. Transgenic Arabidopsis plants overexpressing AtC3H14 (i.e., 35S::AtC3H14 plants) produced dwarfing phenotypes. 35S::AtC3H14 plants developed phloem fibers earlier than wild-type and this phenotype was more pronounced in the roots. Interestingly, ectopic secondary wall thickenings were found in both stems and roots. These phenotypic consequences are successively reproduced from the 35S::AtC3H15 and 35S::PtrC3H14-1 plants. Whole transcriptome GeneChip analysis identified that the ‘cell wall’ and ‘extracellular’-related genes are extremely over-represented in the stem tissues of 35S::AtC3H14 plants. These results suggest that AtC3H14 may act as a negative regulator of cell elongation with modification of cell wall reassembly and be involved in the secondary wall formation in Arabidopsis.