Project description:Differentiation of Arabidopsis guard cells: analysis of the networks incorporating the basic helix-loop helix transcription factor, FAMA
Project description:A cascade of basic helix-loop-helix transcription factors guide tapetal cell development in maize anthers, using proteins conserved in Arabidopsis and rice but deployed with a distinctive timing. Anthers were dissected and staged to be 1500 μm in length (+/- 100 μm) and samples were compared between mutants and fertile siblings on an Agilent 4x44 custom microarray. Analysis included MS32 which is another basic helix-loop-helix factor that acts later during tapetal differentiation.
Project description:The trade-off between growth and immunity is crucial for survival in plants. An antagonistic interaction has been observed between the growth-promoting hormone brassinosteroid and pathogen associated molecular pattern (PAMP) signals, which induce immunity but inhibit growth, however the underlying molecular mechanism has remained unclear. The PRE-IBH1-HBI1 triple helix-loop-helix/basic helix-loop-helix (HLH/bHLH) cascade has been shown to mediate growth responses to several hormonal and environmental signals, but its downstream targets and role in immunity remain unknown. Here, we performed genome-wide analyses of HBI1 target genes in Arabidopsis. The results show that HBI1 regulates a set of genes that largely overlaps with targets of PIFs, but displays both similar and unique transcriptional activities compared to PIFs, supporting a role in fine-tuning the network through cooperation and antagonism with other DNA-binding factors of the network. Furthermore, HBI1 also negatively regulates a subset of defense response genes. Two PAMPs, flagellin and elongation factor, repressed HBI1 expression, whereas overexpression of HBI1 reduced the PAMP-induced growth inhibition, defense gene expression, reactive oxygen species (ROS) production, and flg22-induced resistance to Pseudomonas syringae pathovar tomato DC3000. These data indicate that HBI1 is a node for crosstalk between hormone and immune pathways. This study demonstrates that the PRE-IBH1-HBI1 module integrates hormone and pathogen signals, and thus plays a central role in the balance between growth and immunity in plants. Genome wide analysis the HBI1 binding target
Project description:The trade-off between growth and immunity is crucial for survival in plants. An antagonistic interaction has been observed between the growth-promoting hormone brassinosteroid and pathogen associated molecular pattern (PAMP) signals, which induce immunity but inhibit growth, however the underlying molecular mechanism has remained unclear. The PRE-IBH1-HBI1 triple helix-loop-helix/basic helix-loop-helix (HLH/bHLH) cascade has been shown to mediate growth responses to several hormonal and environmental signals, but its downstream targets and role in immunity remain unknown. Here, we performed genome-wide analyses of HBI1 target genes in Arabidopsis. The results show that HBI1 regulates a set of genes that largely overlaps with targets of PIFs, but displays both similar and unique transcriptional activities compared to PIFs, supporting a role in fine-tuning the network through cooperation and antagonism with other DNA-binding factors of the network. Furthermore, HBI1 also negatively regulates a subset of defense response genes. Two PAMPs, flagellin and elongation factor, repressed HBI1 expression, whereas overexpression of HBI1 reduced the PAMP-induced growth inhibition, defense gene expression, reactive oxygen species (ROS) production, and flg22-induced resistance to Pseudomonas syringae pathovar tomato DC3000. These data indicate that HBI1 is a node for crosstalk between hormone and immune pathways. This study demonstrates that the PRE-IBH1-HBI1 module integrates hormone and pathogen signals, and thus plays a central role in the balance between growth and immunity in plants. Compare the transcriptome of HBI1-Ox and wild type.
Project description:In plants, basic helix-loop-helix (bHLH) transcription factors play important roles in the control of cell elongation. Two bHLH proteins, PACLOBTRAZOL RESISTANCE1 (PRE1) and Arabidopsis ILI1 binding bHLH1 (IBH1), antagonistically regulate cell elongation in response to brassinosteroid and gibberellin signaling, but the detailed molecular mechanisms by which these factors regulate cell elongation remain unclear. Here, we identify the bHLH transcriptional activators for cell elongation (ACEs) and demonstrate that PRE1, IBH1, and the ACEs constitute a triantagonistic bHLH system that competitively regulates cell elongation. In this system, the ACE bHLH transcription factors directly activate the expression of enzyme genes for cell elongation by interacting with their promoter regions. IBH1 negatively regulates cell elongation by interacting with the ACEs and thus interfering with their DNA binding. PRE1 interacts with IBH1 and counteracts the ability of IBH1 to affect ACEs. Therefore, PRE1 restores the transcriptional activity of ACEs, resulting in induction of cell elongation. The balance of triantagonistic bHLH proteins, ACEs, IBH1, and PRE1, might be important for determination of the size of plant cells. The expression of IBH1 and PRE1 is regulated by brassinosteroid, gibberellins, and developmental phase dependent factors, indicating that two phytohormones and phase-dependent signals are integrated by this triantagonistic bHLH system.