Cytokinins influence root gravitropism via differential regulation of auxin transporter expression and localization in <i>Arabidopsis</i>

Pernisová, Markéta; Prát, Tomáš; Grones, Peter; Haruštiaková, Danka; Matonohova, Martina; Spíchal, Lukáš; Nodzyński, Tomasz; Friml, Jiřı́; Hejátko, Jan

doi:10.1111/nph.14049

Cited by 46 publications

(45 citation statements)

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“…Depletion of endogenous cytokinins by overexpressing CYTOKININ OXIDASE DEHYDROGENASE ( CKX ) genes caused lateral expansion of the auxin maxima, i.e., from columella to lateral root cap (Pernisová et al, 2009). Further, cytokinin signaling defective mutant ahk3 and cytokinin deficient Pro35S:AtCKX transgenic lines showed defects in both auxin redistribution as well as root gravitropic response (Pernisova et al, 2016). Upon gravistimulation, the AtCKX3 overexpression and ahk3 mutant lines showed WT like pattern for PIN3 and PIN7 relocalization in columella while the pin3pin4pin7 triple mutant did not show any defect in cytokinin sensitivity.…”

Section: Cytokinins and Its Role In Root Gravitropismmentioning

confidence: 99%

“…Upon gravistimulation, the AtCKX3 overexpression and ahk3 mutant lines showed WT like pattern for PIN3 and PIN7 relocalization in columella while the pin3pin4pin7 triple mutant did not show any defect in cytokinin sensitivity. On the other hand, depleting endogenous cytokinins via AtCKX overexpression caused alteration in cellular distribution of auxin influx carrier AUX1 suggesting that cytokinin largely targets AUX1-mediated auxin transport rather than PIN-mediated auxin transport to affect root gravitropism (Pernisova et al, 2016). In an interesting finding, role of cytokinin was established in cytokinin-induced root tip reorientation growth response which involves members of two-component system, i.e., ARABIDOPSIS HISTIDINE KINASEs (AHKs); and type-A and type-B RESPONSE REGULATORs (ARRs) (Kushwah et al, 2011).…”

Section: Cytokinins and Its Role In Root Gravitropismmentioning

confidence: 99%

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Striking the Right Chord: Signaling Enigma during Root Gravitropism

2017

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Plants being sessile can often be judged as passive acceptors of their environment. However, plants are actually even more active in responding to the factors from their surroundings. Plants do not have eyes, ears or vestibular system like animals, still they “know” which way is up and which way is down? This is facilitated by receptor molecules within plant which perceive changes in internal and external conditions such as light, touch, obstacles; and initiate signaling pathways that enable the plant to react. Plant responses that involve a definite and specific movement are called “tropic” responses. Perhaps the best known and studied tropisms are phototropism, i.e., response to light, and geotropism, i.e., response to gravity. A robust root system is vital for plant growth as it can provide physical anchorage to soil as well as absorb water, nutrients and essential minerals from soil efficiently. Gravitropic responses of both primary as well as lateral root thus become critical for plant growth and development. The molecular mechanisms of root gravitropism has been delved intensively, however, the mechanism behind how the potential energy of gravity stimulus converts into a biochemical signal in vascular plants is still unknown, due to which gravity sensing in plants still remains one of the most fascinating questions in molecular biology. Communications within plants occur through phytohormones and other chemical substances produced in plants which have a developmental or physiological effect on growth. Here, we review current knowledge of various intrinsic signaling mechanisms that modulate root gravitropism in order to point out the questions and emerging developments in plant directional growth responses. We are also discussing the roles of sugar signals and their interaction with phytohormone machinery, specifically in context of root directional responses.

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Section: Cytokinins and Its Role In Root Gravitropismmentioning

confidence: 99%

Section: Cytokinins and Its Role In Root Gravitropismmentioning

confidence: 99%

Striking the Right Chord: Signaling Enigma during Root Gravitropism

2017

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“…The increase and decrease of cytokinin levels have been shown to slightly accelerate the rate of gravitropic bending in primary root, but the developmental importance of this effect remains uncertain (Pernisova et al, 2016). In contrast, we show here that CK signaling plays a developmental role in establishing the primary GSA of LRs.…”

Section: Discussionmentioning

confidence: 99%

Cytokinin functions as an asymmetric and anti-gravitropic signal in lateral roots

Waidmann

Rosquete

Schöller

et al. 2019

Preprint

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31Directional organ growth allows the plant root system to strategically cover its 32 surroundings. Intercellular auxin transport is aligned with the gravity vector in 33 the primary root tips, facilitating downward organ bending at the lower root 34 flank. Here we show that cytokinin signaling functions as a lateral root specific 35 anti-gravitropic component, promoting the radial distribution of the root system. 36 We performed a genome-wide association study and revealed that signal peptide 37 processing of Cytokinin Oxidase 2 (CKX2) affects its enzymatic activity and, 38 thereby, determines the degradation of cytokinins in natural Arabidopsis 39 thaliana accessions. Cytokinin signaling interferes with growth at the upper 40 lateral root flank and thereby prevents downward bending. Our interdisciplinary 41 approach revealed that two phytohormonal cues at opposite organ flanks 42 counterbalance each other's negative impact on growth, suppressing organ 43 growth towards gravity and allow for radial expansion of the root system. 44 45 128 regulate angular growth of LRs, we initially transferred 7-day old seedlings of the 129 reference accession Col-0 to medium supplemented with CKs. We observed a 130 concentration-dependent increase in GSA values of LRs emerging in presence of 131 6active CKs, such as 6-Benzylaminopurin (BAP) ( Figure 2D), trans-zeatin (tZ) and 132 isopentenyladenine (iP) ( Figure S3F and G). Conversely, CK receptor mutants showed 133 accelerated bending of LRs and accordingly decreased GSA values ( Figure 2E). 134These data suggest that cytokinin signaling interferes with downward bending of 135 emerged LRs. Notably, emerging LRs of winter oilseed rape also displayed reduced 136 bending of LRs when treated with BAP ( Figure S3H), suggesting that the effect of CK 137 on directional LR growth is likely to be conserved. 138To further assess the importance of CKX2 in GSA establishment, we disrupted 139 CKX activity in the reference accession Col-0. Treatments with the CKX inhibitor 140 INCYDE (Zatloukal et al., 2008) phenocopied the ckx2 loss-of-function mutant, both 141 displaying more horizontal LRs when compared to its respective controls (Figure 2F, 142 G). On the other hand, CKX2 overexpressing (OX) plants showed accelerated bending 143 of LRs, phenocopying the CK receptor mutants (Figure 2G). These data suggest that 144 CK signaling defines directional lateral root growth by reducing LR bending after 145 emergence. 146 147 157 ARR4 (pARR3:GUS/ pARR4:GUS; Figure S4C)). Moreover, angular growth of LRs 158 was not altered in arr3 or arr4 mutants ( Figure S4D). On the other hand, we confirmed 159 expression of CRF2 and CRF3 in the early stages of LR development ( Figure 3A and 160 S4E). pCRF2:GFP-GUS was ubiquitously expressed in young LRs, while pCRF3:GFP-161 GUS was preferentially expressed in cortical and epidermal cell files ( Figure 3A and 162 S4E). Notably, compared to emerged laterals, the main root displayed much weaker 163 CRF2 and CRF3 expression ( Figure S4F), suggesting that CRF2 an...

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“…When a primary root is growing vertically downward, PIN3 and PIN7 localisation is essentially apolar. Upon gravistimulation however, both PIN3 and PIN7 can become rapidly relocalised to accumulate preferentially on the lateral, lower-most face of the columella cells (Friml et al, 2002;Kleine-Vehn et al, 2010;Pernisova et al, 2016). This polarization of PIN3 and PIN7 within the statocytes appears to be an important early step in generating the asymmetry in auxin distribution between upper and lower halves of the root tip.…”

Section: Introductionmentioning

confidence: 99%

Antagonistic and auxin-dependent phosphoregulation of columella PIN proteins controls lateral root gravitropic setpoint angle in Arabidopsis

Roychoudhry

Sageman-Furnas

Wolverton

et al. 2019

Preprint

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Lateral roots of many species are maintained at non-vertical angles with respect to gravity.These gravitropic setpoint angles (GSAs) are intriguing because their maintenance requires that roots are able to effect gravitropic response both with and against the gravity vector.Here we have used the Arabidopsis lateral root in order to investigate the molecular basis of the maintenance of non-vertical GSAs. We show that gravitropism in the lateral root is angledependent and that both upward and downward graviresponse requires auxin transport and the generation of auxin asymmetries consistent with the Cholodny-Went model. We show that the symmetry in auxin distribution in lateral roots growing at GSA can be traced back to *

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Cytokinins influence root gravitropism via differential regulation of auxin transporter expression and localization in Arabidopsis

Cited by 46 publications

References 62 publications

Striking the Right Chord: Signaling Enigma during Root Gravitropism

Striking the Right Chord: Signaling Enigma during Root Gravitropism

Cytokinin functions as an asymmetric and anti-gravitropic signal in lateral roots

Antagonistic and auxin-dependent phosphoregulation of columella PIN proteins controls lateral root gravitropic setpoint angle in Arabidopsis

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