Patterning the Axes: A Lesson from the Root

Mambro, Riccardo Di; Sabatini, Sabrina; Ioio, Raffaele Dello

doi:10.3390/plants8010008

Cited by 20 publications

(26 citation statements)

References 85 publications

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“…PHB and PHV Control MC Formation via the Regulation of the CYCLIN D6;1 (CYCD6;1) Expression Domain In Arabidopsis, expression of PHABULOSA (PHB) and of its redundant homologous PHAVOLUTA (PHV) is restricted to the vascular tissue due to the repressive activity of microRNA165 (miRNA165) and 166 in the ground tissue (GT). [8][9][10] We have recently shown that miR165-and 166-resistant mutants of PHB and PHV (phb-1d and phv-1d, respectively), where PHB and PHV are present also in the GT, have supernumerary cortex formation already during early phase of root development, suggesting that these transcription factors regulate GT patterning. 11 Because Arabidopsis plants acquire an additional cortical layer in late post-embryonic root development ( Figures 1A and 1B), we assessed whether PHB and PHV control middle cortex (MC) formation analyzing MC development in phb,phv loss-of-function plants (phb-13, phv-11).…”

Section: Resultsmentioning

confidence: 99%

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A PHABULOSA-Controlled Genetic Pathway Regulates Ground Tissue Patterning in the Arabidopsis Root

Bertolotti¹,

Unterholzner

Scintu³

et al. 2021

Current Biology

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Summary In both animals and plants, development involves anatomical modifications. In the root of Arabidopsis thaliana , maturation of the ground tissue (GT)—a tissue comprising all cells between epidermal and vascular ones—is a paradigmatic example of these modifications, as it generates an additional tissue layer, the middle cortex (MC). 1 , 2 , 3 , 4 In early post-embryonic phases, the Arabidopsis root GT is composed of one layer of endodermis and one of cortex. A second cortex layer, the MC, is generated by asymmetric cell divisions in about 80% of Arabidopsis primary roots, in a time window spanning from 7 to 14 days post-germination (dpg). The cell cycle regulator CYCLIN D6;1 (CYCD6;1) plays a central role in this process, as its accumulation in the endodermis triggers the formation of MC. 5 The phytohormone gibberellin (GA) is a key regulator of the timing of MC formation, as alterations in its signaling and homeostasis result in precocious endodermal asymmetric cell divisions. 3 , 6 , 7 However, little is known on how GAs are regulated during GT maturation. Here, we show that the HOMEODOMAIN LEUCINE ZIPPER III (HD-ZIPIII) transcription factor PHABULOSA (PHB) is a master regulator of MC formation, controlling the accumulation of CYCD6;1 in the endodermis in a cell non-autonomous manner. We show that PHB activates the GA catabolic gene GIBBERELLIN 2 OXIDASE 2 ( GA2ox2 ) in the vascular tissue, thus regulating the stability of the DELLA protein GIBBERELLIN INSENSITIVE (GAI)—a GA signaling repressor—in the root and, hence, CYCD6;1 expression in the endodermis.

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Section: Resultsmentioning

confidence: 99%

“…Please cite this article in press as: Bertolotti et al, A PHABULOSA-Controlled Genetic Pathway Regulates Ground Tissue Patterning in the Arabidopsis Root, Current Biology (2020), https://doi.org/10.1016/j.cub.2020. 10…”

Section: Ll Open Accessmentioning

confidence: 99%

A PHABULOSA-Controlled Genetic Pathway Regulates Ground Tissue Patterning in the Arabidopsis Root

Bertolotti¹,

Unterholzner

Scintu³

et al. 2021

Current Biology

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“…For root length measurements, plates were photographed and the resulting images were analyzed using the analysis software ImageJ 1.47v available online (https://imagej.nih.gov/ij/). Root meristem size of 5 days post germination plants was measured based on the number of cortex cells in a file extending from the quiescent center to the first elongated cortex cell excluded, as described previously [38][39][40]. Images were obtained using a confocal laser scanning microscope (Zeiss LSM 780).…”

Section: Root Length Meristem Size and Cell Size Analysismentioning

confidence: 99%

The Lateral Root Cap Acts as an Auxin Sink that Controls Meristem Size

Mambro

Svolacchia²,

Ioio³

et al. 2019

Current Biology

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“…Organ growth in plants is supported by the meristems, regions providing a reservoir of undifferentiated cells whose activity depends on the stem cell niche [1]. In the root, the stem cells daughters proliferate establishing the division zone of the meristem and, more distally from the root tip along the longitudinal axis, those cells differentiate generating the differentiation zone [2,3,4,5]. The boundary between proliferating and differentiating cells is called transition zone (TZ).…”

Section: Introductionmentioning

confidence: 99%

Cytokinin-Dependent Control of GH3 Group II Family Genes in the Arabidopsis Root

Pierdonati¹,

Unterholzner²,

Salvi³

et al. 2019

Plants

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The Arabidopsis root is a dynamic system where the interaction between different plant hormones controls root meristem activity and, thus, organ growth. In the root, a characteristic graded distribution of the hormone auxin provides positional information, coordinating the proliferating and differentiating cell status. The hormone cytokinin shapes this gradient by positioning an auxin minimum in the last meristematic cells. This auxin minimum triggers a cell developmental switch necessary to start the differentiation program, thus, regulating the root meristem size. To position the auxin minimum, cytokinin promotes the expression of the IAA-amido synthase group II gene GH3.17, which conjugates auxin with amino acids, in the most external layer of the root, the lateral root cap tissue. Since additional GH3 genes are expressed in the root, we questioned whether cytokinin to position the auxin minimum also operates via different GH3 genes. Here, we show that cytokinin regulates meristem size by activating the expression of GH3.5 and GH3.6 genes, in addition to GH3.17. Thus, cytokinin activity provides a robust control of auxin activity in the entire organ necessary to regulate root growth.

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Patterning the Axes: A Lesson from the Root

Cited by 20 publications

References 85 publications

A PHABULOSA-Controlled Genetic Pathway Regulates Ground Tissue Patterning in the Arabidopsis Root

A PHABULOSA-Controlled Genetic Pathway Regulates Ground Tissue Patterning in the Arabidopsis Root

The Lateral Root Cap Acts as an Auxin Sink that Controls Meristem Size

Cytokinin-Dependent Control of GH3 Group II Family Genes in the Arabidopsis Root

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