Acidic cell elongation drives cell differentiation in the
            <i>Arabidopsis</i>
            root

Pacifici, Elena; Mambro, Riccardo Di; Ioio, Raffaele Dello; Costantino, Paolo; Sabatini, Sabrina

doi:10.15252/embj.201899134

Cited by 82 publications

(98 citation statements)

References 23 publications

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“…Cytokinin concentrations were developmentally driven as the positive correlation between total cytokinin concentration and fruit weight held true also within each treatment, in agreement with Pilkington et al [15]. Further experimentation will be required to clarify the mechanism and if, similar to Arabidopsis roots, the signalling may be mediated by a type-B RR [44].…”

Section: Discussionsupporting

confidence: 80%

“…A meta-analysis of cytokinin effects on Arabidopsis transcriptome identified expansins as targets of cytokinin signalling [43]. Expansins drive acidic cell elongation in Arabidopsis roots, where α-expansinA genes and plasma membrane H(+)-ATPase are controlled by cytokinins via ARR1 [44]. In soybean, cytokinins regulate the expression of expansin and cell wall expansion [45].…”

Section: Discussionmentioning

confidence: 99%

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Phytohormone and Transcriptomic Analysis Reveals Endogenous Cytokinins Affect Kiwifruit Growth under Restricted Carbon Supply

et al. 2020

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Following cell division, fruit growth is characterized by both expansion through increases in cell volume and biomass accumulation in cells. Fruit growth is limited by carbon starvation; however, the mechanism controlling fruit growth under restricted carbohydrate supply is poorly understood. In a previous study using red-fleshed kiwifruit, we showed that long-term carbon starvation had detrimental effects on carbohydrate, anthocyanin metabolism, and fruit growth. To elucidate the mechanisms underlying the reduction in fruit growth during kiwifruit development, we integrated phytohormone profiling with transcriptomic and developmental datasets for fruit under high or low carbohydrate supplies. Phytohormone profiling of the outer pericarp tissue of kiwifruit showed a 6-fold reduction in total cytokinin concentrations in carbon-starved fruit, whilst other hormones were less affected. Principal component analysis visualised that cytokinin composition was distinct between fruit at 16 weeks after mid bloom, based on their carbohydrate supply status. Cytokinin biosynthetic genes (IPT, CYP735A) were significantly downregulated under carbon starvation, in agreement with the metabolite data. Several genes that code for expansins, proteins involved in cell wall loosening, were also downregulated under carbon starvation. In contrast to other fleshy fruits, our results suggest that cytokinins not only promote cell division, but also drive fruit cell expansion and growth in kiwifruit.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Phytohormone and Transcriptomic Analysis Reveals Endogenous Cytokinins Affect Kiwifruit Growth under Restricted Carbon Supply

et al. 2020

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“…The growth of plant cells is in tight relationship with cell wall loosening, which can be mediated by expansins. Recently, interplay between CK and expansin in root development has been reported (Pacifici et al ., ). These authors suggested that ARR1 stimulates EXPA1‐driven cell wall loosening and consequent cell elongation in Arabidopsis roots.…”

Section: Discussionmentioning

confidence: 97%

Multifaceted activity of cytokinin in leaf development shapes its size and structure in Arabidopsis

et al. 2019

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The phytohormone cytokinin has been shown to affect many aspects of plant development ranging from the regulation of the shoot apical meristem to leaf senescence. However, some studies have reported contradictory effects of cytokinin on leaf physiology. Therefore cytokinin treatments cause both chlorosis and increased greening and both lead to decrease or increase in cell size. To elucidate this multifaceted role of cytokinin in leaf development, we have employed a system of temporal controls over the cytokinin pool and investigated the consequences of modulated cytokinin levels in the third leaf of Arabidopsis. We show that, at the cell proliferation phase, cytokinin is needed to maintain cell proliferation by blocking the transition to cell expansion and the onset of photosynthesis. Transcriptome profiling revealed regulation by cytokinin of a gene suite previously shown to affect cell proliferation and expansion and thereby a molecular mechanism by which cytokinin modulates a molecular network underlying the cellular responses. During the cell expansion phase, cytokinin stimulates cell expansion and differentiation. Consequently, a cytokinin excess at the cell expansion phase results in an increased leaf and rosette size fueled by higher cell expansion rate, yielding higher shoot biomass. Proteome profiling revealed the stimulation of primary metabolism by cytokinin, in line with an increased sugar content that is expected to increase turgor pressure, representing the driving force of cell expansion. Therefore, the developmental timing of cytokinin content fluctuations, together with a tight control of primary metabolism, is a key factor mediating transitions from cell proliferation to cell expansion in leaves.

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“…EXPA1 was reported to be induced by cytokinin in the root, which is involved in controlling cell differentiation initiation (Bhargava et al ., ; Pacifici et al ., ). Interestingly, the development of root hairs was delayed in the expa1 mutant, indicating a setback in cell differentiation (Pacifici et al ., ). These data support the hypothesis that EXPA1 could be connected to the root hair phenotype of AtERF#111‐OE plants.…”

Section: Discussionmentioning

confidence: 97%

AtERF#111/ABR1 is a transcriptional activator involved in the wounding response

et al. 2019

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AtERF#111/ABR1 belongs to the group X of the ERF/AP2 transcription factor family (GXERFs) and is shoot specifically induced under submergence and hypoxia. It was described to be an ABA-response repressor, but our data reveal a completely different function. Surprisingly, AtERF#111 expression is strongly responsive to wounding stress. Expression profiling of ERF#111-overexpressing (OE) plants, which show morphological phenotypes like increased root hair length and number, strengthens the hypothesis of AtERF#111 being involved in the wounding response, thereby acting as a transcriptional activator of gene expression. Consistent with a potential function outside of oxygen signalling, we could not assign AtERF#111 as a target of the PRT6 N-degron pathway, even though it starts with a highly conserved N-terminal MetÀCys (MC) motif. However, the protein is unstable as it is degraded in an ubiquitin-dependent manner. Finally, direct target genes of AtERF#111 were identified by microarray analyses and subsequently confirmed by protoplast transactivation assays. The special roles of diverse members of the plant-specific GXERFs in coordinating stress signalling and wound repair mechanisms have been recently hypothesized, and our data suggest that AtERF#111 is indeed involved in these processes.For hypoxia treatments, 7-day-old seedlings grown on MS medium were used. 2 h after the onset of the photoperiod, open Petri dishes were placed into a desiccator for the indicated time periods

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Acidic cell elongation drives cell differentiation in the Arabidopsis root

Cited by 82 publications

References 23 publications

Phytohormone and Transcriptomic Analysis Reveals Endogenous Cytokinins Affect Kiwifruit Growth under Restricted Carbon Supply

Phytohormone and Transcriptomic Analysis Reveals Endogenous Cytokinins Affect Kiwifruit Growth under Restricted Carbon Supply

Multifaceted activity of cytokinin in leaf development shapes its size and structure in Arabidopsis

AtERF#111/ABR1 is a transcriptional activator involved in the wounding response

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