Identification of a <i>cis</i>‐regulatory element for L1 layer‐specific gene expression, which is targeted by an L1‐specific homeodomain protein

Abe, Mitsutomo; Takahashi, Taku; Komeda, Yoshibumi

doi:10.1046/j.1365-313x.2001.01047.x

Cited by 193 publications

(205 citation statements)

References 38 publications

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“…In vitro HDbinding site selection experiments have revealed 5Ј-GCATTATTTTGC-3Ј as consensus sequence for four HD-ZIP IVs: HDG7, HDG9, AtML1 and PDF2 (Nakamura et al, 2006). The well-described L1 and HAHR1 boxes overlap with this consensus sequence (Abe et al, 2001;Tron et al, 2001). Although this experiment has not been performed for HDG2, it is most likely that HDG2 and AtML1, when overexpressed, bind to common in vivo target sequences for the following reasons.…”

Section: Discussionmentioning

confidence: 99%

Arabidopsishomeodomain-leucine zipper IV proteins promote stomatal development and ectopically induce stomata beyond the epidermis

et al. 2013

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SUMMARYThe shoot epidermis of land plants serves as a crucial interface between plants and the atmosphere: pavement cells protect plants from desiccation and other environmental stresses, while stomata facilitate gas exchange and transpiration. Advances have been made in our understanding of stomatal patterning and differentiation, and a set of 'master regulatory' transcription factors of stomatal development have been identified. However, they are limited to specifying stomatal differentiation within the epidermis. Here, we report the identification of an Arabidopsis homeodomain-leucine zipper IV (HD-ZIP IV) protein, HOMEODOMAIN GLABROUS2 (HDG2), as a key epidermal component promoting stomatal differentiation. HDG2 is highly enriched in meristemoids, which are transient-amplifying populations of stomatal-cell lineages. Ectopic expression of HDG2 confers differentiation of stomata in internal mesophyll tissues and occasional multiple epidermal layers. Conversely, a loss-of-function hdg2 mutation delays stomatal differentiation and, rarely but consistently, results in aberrant stomata. A closely related HD-ZIP IV gene, Arabidopsis thaliana MERISTEM LAYER1 (AtML1), shares overlapping function with HDG2: AtML1 overexpression also triggers ectopic stomatal differentiation in the mesophyll layer and atml1 mutation enhances the stomatal differentiation defects of hdg2. Consistently, HDG2 and AtML1 bind the same DNA elements, and activate transcription in yeast. Furthermore, HDG2 transactivates expression of genes that regulate stomatal development in planta. Our study highlights the similarities and uniqueness of these two HD-ZIP IV genes in the specification of protodermal identity and stomatal differentiation beyond predetermined tissue layers.

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Section: Discussionmentioning

confidence: 99%

Arabidopsishomeodomain-leucine zipper IV proteins promote stomatal development and ectopically induce stomata beyond the epidermis

et al. 2013

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“…5,6 However, not all the L1 box-containing genes tested were upregulated in ATML1-overexpressing lines. 5 For example, PDF1 was not significantly upregulated in ATML1-overexpressing plants, whereas loss of ATML1 and PDF2 activity resulted in decreased PDF1 expression.…”

Section: Atml1 Activates the Expression Of Epidermis-specific Genesmentioning

confidence: 97%

Induction of epidermal cell fate in Arabidopsis shoots

Takada

Yoshida

2013

Plant Signaling & Behavior

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Land plants have evolved a cuticle-bearing epidermis to protect themselves from environmental stress and pathogen attack. Despite its important role, little is known about the molecular mechanisms regulating shoot epidermal cell identity. In a recent study, we found that the Arabidopsis thaliana ATML1 gene is possibly a master regulator of shoot epidermal cell fate. We revealed that ATML1 has the ability to confer shoot epidermis-related traits to non-epidermal cells of the seedlings. These data are consistent with the previous loss-of-function mutant analyses, which implied a positive role of ATML1 in epidermal cell differentiation. Importantly, ectopic epidermal cells induced in ATML1-overexpressing lines provide a novel tool to assess the intrinsic properties of epidermal cells and to study epistatic interactions among genes involved in epidermal/mesophyll differentiation. Using this system, we obtained data revealing that ATML1 negatively influenced mesophyll cell fate. In addition, we provided a working model of how division planes in epidermal cells are determined.The specification of plant shoot epidermal cells during development remains unknown. It has been suggested that ATML1, an HD-ZIP class IV transcription factor, is a key regulator of epidermal cell differentiation.1 ATML1 is specifically expressed in the shoot epidermis, and loss-of-function mutations in ATML1 and its closest homolog PDF2 severely affect epidermal cell differentiation of leaves. [1][2][3][4] We recently reported ATML1 gain-of-function experiments for the first time, and revealed that ATML1 is able to confer epidermal cell fate in non-epidermal tissues of the seedlings. 5 In this addendum, we summarize and further discuss our major findings and provide a perspective for future research in this field. ATML1 Activates the Expression of Epidermis-Specific GenesOur overexpression studies revealed that ATML1 activated expression of several epidermis-specific genes, which contain ATML1-binding sites (L1 box) in their promoters, suggesting that ATML1 acts on the promoters of these genes. 5,6However, not all the L1 box-containing genes tested were upregulated in ATML1-overexpressing lines.5 For example, PDF1 was not significantly upregulated in ATML1-overexpressing plants, whereas loss of ATML1 and PDF2 activity resulted in decreased PDF1 expression.

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“…13 HD-Zip IV family transcription factors specifying epidermal cell identity during various stages in epidermal cell differentiation also regulate some cuticle related genes via the L1-box in their promoters. 1,[20][21][22] Mutants of these HD-Zip IV transcription factors showed protodermal and epidermal defects in early developmental stages, or no phenotype due to redundancy. 20,21 Cuticle development in leaves after differentiation of epidermal cells requires LCR and CER1, and other cutin and wax synthesizing enzyme and transporter genes (with or without the L1-box in their promoters).…”

Section: ′mentioning

confidence: 99%

The MIXTA-like Transcription factor MYB16 is a major regulator of cuticle formation in vegetative organs

Oshima

Mitsuda

2013

Plant Signaling & Behavior

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Identification of a cis‐regulatory element for L1 layer‐specific gene expression, which is targeted by an L1‐specific homeodomain protein

Cited by 193 publications

References 38 publications

Arabidopsishomeodomain-leucine zipper IV proteins promote stomatal development and ectopically induce stomata beyond the epidermis

Arabidopsishomeodomain-leucine zipper IV proteins promote stomatal development and ectopically induce stomata beyond the epidermis

Induction of epidermal cell fate in Arabidopsis shoots

The MIXTA-like Transcription factor MYB16 is a major regulator of cuticle formation in vegetative organs

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