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1.
Plant J ; 99(6): 1080-1097, 2019 09.
Article in English | MEDLINE | ID: mdl-31059179

ABSTRACT

Arabidopsis MYC2 bHLH transcription factor plays a negative regulatory role in blue light (BL)-mediated seedling development. HY5 bZIP protein works as a positive regulator of multiple wavelengths of light and promotes photomorphogenesis. Both MYC2 and HY5, belonging to two different classes of transcription factors, are the integrators of multiple signaling pathways. However, the functional interrelations of these two transcription factors in seedling development remain unknown. Additionally, whereas HY5-mediated regulation of gene expression has been investigated in detail, the transcriptional regulation of HY5 itself is yet to be understood. Here, we show that HY5 and MYC2 work in an antagonistic manner in Arabidopsis seedling development. Our results reveal that HY5 expression is negatively regulated by MYC2 predominantly in BL, and at various stages of development. On the other hand, HY5 negatively regulates the expression of MYC2 at various wavelengths of light. In vitro and in vivo DNA-protein interaction studies suggest that MYC2 binds to the E-box cis-acting element of HY5 promoter. Collectively, this study demonstrates a coordinated regulation of MYC2 and HY5 in blue-light-mediated Arabidopsis seedling development.


Subject(s)
Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Arabidopsis/genetics , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Basic-Leucine Zipper Transcription Factors/genetics , Basic-Leucine Zipper Transcription Factors/metabolism , Seedlings/genetics , Anthocyanins/metabolism , Arabidopsis/growth & development , Arabidopsis/metabolism , Arabidopsis/radiation effects , Chlorophyll/metabolism , Gene Expression Regulation, Plant/genetics , Gene Expression Regulation, Plant/radiation effects , Gravitropism/genetics , Light , Microscopy, Fluorescence , Mutation , Phenotype , Plant Roots/genetics , Plant Roots/metabolism , Promoter Regions, Genetic , Protein Binding , Seedlings/growth & development , Seedlings/metabolism , Signal Transduction/genetics , Signal Transduction/radiation effects , Two-Hybrid System Techniques
2.
Plant Cell ; 26(8): 3343-57, 2014 Aug.
Article in English | MEDLINE | ID: mdl-25139007

ABSTRACT

Mitogen-activated protein kinase (MAPK) pathways are involved in several signal transduction processes in eukaryotes. Light signal transduction pathways have been extensively studied in plants; however, the connection between MAPK and light signaling pathways is currently unknown. Here, we show that MKK3-MPK6 is activated by blue light in a MYC2-dependent manner. MPK6 physically interacts with and phosphorylates a basic helix-loop-helix transcription factor, MYC2, and is phosphorylated by a MAPK kinase, MKK3. Furthermore, MYC2 binds to the MPK6 promoter and regulates its expression in a feedback regulatory mechanism in blue light signaling. We present mutational and physiological studies that illustrate the function of the MKK3-MPK6-MYC2 module in Arabidopsis thaliana seedling development and provide a revised mechanistic view of photomorphogenesis.


Subject(s)
Arabidopsis Proteins/physiology , Arabidopsis/growth & development , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/physiology , Light , MAP Kinase Kinase 3/physiology , MAP Kinase Signaling System/physiology , Mitogen-Activated Protein Kinases/physiology , Arabidopsis/genetics , Arabidopsis/radiation effects , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/genetics , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Gene Expression Regulation, Plant , MAP Kinase Kinase 3/genetics , MAP Kinase Kinase 3/metabolism , Mitogen-Activated Protein Kinases/genetics , Mitogen-Activated Protein Kinases/metabolism , Phosphorylation , Seedlings/genetics , Seedlings/growth & development , Seedlings/radiation effects
3.
Plant J ; 83(3): 439-50, 2015 Aug.
Article in English | MEDLINE | ID: mdl-26047210

ABSTRACT

Regulations of Arabidopsis seedling growth by two proteins, which belong to different classes of transcription factors, are poorly understood. MYC2 and GBF1 belong to bHLH and bZIP classes of transcription factors, respectively, and function in cryptochrome-mediated blue light signaling. Here, we have investigated the molecular and functional interrelation of MYC2 and GBF1 in blue light-mediated photomorphogenesis. Our study reveals that MYC2 and GBF1 colocalize and physically interact in the nucleus. This interaction requires the N-terminal domain of each protein. The atmyc2 gbf1 double mutant analyses and transgenic studies have revealed that MYC2 and GBF1 act antagonistically and inhibit the activity of each other to regulate hypocotyl growth and several other biological processes. This study further reveals that MYC2 and GBF1 bind to HYH promoter and inhibit each other through non-DNA binding bHLH-bZIP heterodimers. These results, taken together, provide insights into the mechanistic view on the concerted regulatory role of MYC2 and GBF1 in Arabidopsis seedling development.


Subject(s)
Arabidopsis Proteins/physiology , Arabidopsis/growth & development , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/physiology , Carrier Proteins/physiology , Gene Expression Regulation/physiology , Plant Development/genetics , Transcription Factors/physiology , DNA-Binding Proteins
4.
Front Plant Sci ; 13: 888201, 2022.
Article in English | MEDLINE | ID: mdl-35557737

ABSTRACT

The plant vasculature plays essential roles in the transport of water and nutrients and is composed of xylem and phloem, both of which originate from undifferentiated cells found in the cambium. Development of the different vascular tissues is coordinated by hormonal and peptide signals and culminates in extensive cell wall modifications. Pectins are key cell wall components that are modified during cell growth and differentiation, and pectin fragments function as signals in defence and cell wall integrity pathways, although their role as developmental signals remains tentative. Here, we show that the pectin lyase-like gene PLL12 is required for growth of the vascular bundles in the Arabidopsis inflorescence stem. Although PLL12 was expressed primarily in the phloem, it also affected cambium and xylem growth. Surprisingly, PLL12 overexpression induced ectopic cambium and xylem differentiation in the inflorescence apex and inhibited development of the leaf vasculature. Our results raise the possibility that a cell wall-derived signal produced by PLL12 in the phloem regulates cambium and xylem development.

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