The Yin-Yang of Hormones: Cytokinin and Auxin Interactions in Plant Development

Schäller, G.; Bishopp, Anthony; Kieber, Joseph J.

doi:10.1105/tpc.114.133595

Cited by 484 publications

(399 citation statements)

References 216 publications

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“…Evidence accumulated in the past few years suggests that the distinct distribution of these two hormones plays pivotal roles in tissue patterning (Chandler and Werr, 2015;Schaller et al, 2015). For instance, in the vascular tissue of Arabidopsis roots, a central localized xylem axis bisects the intervening procambium cells and thus forms a bisymmetric structure (Nieminen et al, 2015;De Rybel et al, 2016).…”

Section: Mutually Exclusive Distribution Pattern Of Cytokinin and Auxmentioning

confidence: 99%

Type-B ARABIDOPSIS RESPONSE REGULATORs Specify the Shoot Stem Cell Niche by Dual Regulation of WUSCHEL

et al. 2017

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ORCID IDs: 0000-0003-3103-8629 (W.J.M.); 0000-0002-3129-5206 (X.S.Z.)Plants are known for their capacity to regenerate the whole body through de novo formation of apical meristems from a mass of proliferating cells named callus. Exogenous cytokinin and auxin determine cell fate for the establishment of the stem cell niche, which is the vital step of shoot regeneration, but the underlying mechanisms remain unclear. Here, we show that type-B ARABIDOPSIS RESPONSE REGULATORs (ARRs), critical components of cytokinin signaling, activate the transcription of WUSCHEL (WUS), which encodes a key regulator for maintaining stem cells. In parallel, type-B ARRs inhibit auxin accumulation by repressing the expression of YUCCAs, which encode a key enzyme for auxin biosynthesis, indirectly promoting WUS induction. Both pathways are essential for de novo regeneration of the shoot stem cell niche. In addition, the dual regulation of type-B ARRs on WUS transcription is required for the maintenance of the shoot apical meristem in planta. Thus, our results reveal a long-standing missing link between cytokinin signaling and WUS regulator, and the findings provide critical information for understanding cell fate specification.

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Section: Mutually Exclusive Distribution Pattern Of Cytokinin and Auxmentioning

confidence: 99%

Type-B ARABIDOPSIS RESPONSE REGULATORs Specify the Shoot Stem Cell Niche by Dual Regulation of WUSCHEL

et al. 2017

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“…As vasculature proliferation during de novo root formation associates to J0121-and WIND1-marked cells, requires auxin and cytokinin signaling and involves ALF4, we propose it is a type of callus, and therefore we refer to it as "endogenous callus" to differentiate it from callus obtained by exogenous hormone supplementation. In our model, time-dependent auxin accumulation in a subset of vascular cells activates proliferation, whereas cytokinins might regulate the expression of genes that are directly involved in callus formation (such as WIND1 or ALF4) or that are downstream targets of the auxin signal involved in callus formation (LATERAL ORGAN BOUNDARIES DOMAIN factors; Schaller et al, 2015). Particularly, we found that IAA18 and IAA28 are both involved in endogenous callus formation, although only mutations in IAA18 affect whole regeneration response, whereas ARABIDOPSIS HIS PHOSPHO-TRANSFER PROTEIN1 (AHP1) to AHP3 and ARABIDOPSIS RESPONSE REGULATOR1 (ARR1), ARR10, and ARR12 were involved in vasculature proliferation and regeneration response.…”

Section: Vasculature Proliferation and Endogenous Callus Formationmentioning

confidence: 99%

Regulation of Hormonal Control, Cell Reprogramming, and Patterning during De Novo Root Organogenesis

et al. 2017

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Body regeneration through formation of new organs is a major question in developmental biology. We investigated de novo root formation using whole leaves of Arabidopsis (Arabidopsis thaliana). Our results show that local cytokinin biosynthesis and auxin biosynthesis in the leaf blade followed by auxin long-distance transport to the petiole leads to proliferation of J0121-marked xylem-associated tissues and others through signaling of INDOLE-3-ACETIC ACID INDUCIBLE28 (IAA28), CRANE (IAA18), WOODEN LEG, and ARABIDOPSIS RESPONSE REGULATORS1 (ARR1), ARR10, and ARR12. Vasculature proliferation also involves the cell cycle regulator KIP-RELATED PROTEIN2 and ABERRANT LATERAL ROOT FORMATION4, resulting in a mass of cells with rooting competence that resembles callus formation. Endogenous callus formation precedes specification of postembryonic root founder cells, from which roots are initiated through the activity of SHORT-ROOT, PLETHORA1 (PLT1), and PLT2. Primordia initiation is blocked in shr plt1 plt2 mutant. Stem cell regulators SCHIZORIZA, JACKDAW, BLUEJAY, and SCARECROW also participate in root initiation and are required to pattern the new organ, as mutants show disorganized and reduced number of layers and tissue initials resulting in reduced rooting. Our work provides an organ regeneration model through de novo root formation, stating key stages and the primary pathways involved.Plants have striking regeneration capacities, and can produce new organs from postembryonic tissues (Hartmann et al., 2010;Chen et al., 2014;Liu et al., 2014) as well as reconstitute damaged organs upon wounding (Xu et al., 2006;Heyman et al., 2013; PerianezRodriguez et al., 2014;Melnyk et al., 2015;Efroni et al., 2016). Intriguingly, root regeneration upon stem cell damage recruits embryonic pathways (Hayashi et al., 2006;Efroni et al., 2016), whereas in contrast, postembryonic formation of whole new organs, such as lateral roots, appears to use specific postembryonic pathways (Lavenus et al., 2013).Cross talk between auxin and cytokinin signaling is required for many aspects of plant development and regeneration (El-Showk et al., 2013), although how their synergistic interaction is implemented at the molecular level has not been clarified (Skoog and Miller, 1957;Chandler and Werr, 2015). Exogenous in vitro supplementation of these two hormones results in continuous cell proliferation, to form a characteristic structure termed "callus". Callus emerges as a common regenerative mechanism for almost all plant organs through in vitro culture (Atta et al., 2009;Sugimoto et al., 2010). There is increasing evidence that callus formation requires hormone-mediated activation of a lateral and meristematic root development program in pericycle-like cells defined by expression of the J0121 marker 1 This work was supported by grants from Ministerio de Economía y Competitividad (MINECO) of Spain, the European Regional Development Fund (ERDF) and FP7 Funds of the European Commission, BFU2013-41160-P, BFU2016-80315-P, and PCIG11-GA-2012-322082 to M.A....

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“…2007; Schaller et al. 2015). Interestingly, it has been previously suggested that the transport of auxin might be perturbed by weak electric fields (Morris 1980).…”

Section: Resultsmentioning

confidence: 99%

Externally imposed electric field enhances plant root tip regeneration

2016

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In plants, shoot and root regeneration can be induced in the distinctive conditions of tissue culture (in vitro) but is also observed in intact individuals (in planta) recovering from tissue damage. Roots, for example, can regenerate their fully excised meristems in planta, even in mutants with impaired apical stem cell niches. Unfortunately, to date a comprehensive understanding of regeneration in plants is still missing. Here, we provide evidence that an imposed electric field can perturb apical root regeneration in Arabidopsis. Crucially, we explored both spatial and temporal competences of the stump to respond to electrical stimulation, by varying respectively the position of the cut and the time interval between excision and stimulation. Our data indicate that a brief pulse of an electric field parallel to the root is sufficient to increase by up to two‐fold the probability of its regeneration, and to perturb the local distribution of the hormone auxin, as well as cell division regulation. Remarkably, the orientation of the root towards the anode or the cathode is shown to play a role.

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The Yin-Yang of Hormones: Cytokinin and Auxin Interactions in Plant Development

Cited by 484 publications

References 216 publications

Type-B ARABIDOPSIS RESPONSE REGULATORs Specify the Shoot Stem Cell Niche by Dual Regulation of WUSCHEL

Type-B ARABIDOPSIS RESPONSE REGULATORs Specify the Shoot Stem Cell Niche by Dual Regulation of WUSCHEL

Regulation of Hormonal Control, Cell Reprogramming, and Patterning during De Novo Root Organogenesis

Externally imposed electric field enhances plant root tip regeneration

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