Lateral Root Initiation in Arabidopsis: Developmental Window, Spatial Patterning, Density and Predictability

Dubrovsky, Joseph G.; Gambetta, Grégory A.; Hernández-Barrera, Alejandra; Shishkova, Svetlana; González, I.

doi:10.1093/aob/mcj604

Cited by 168 publications

(179 citation statements)

References 51 publications

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“…The current paradigm for assessing changes in LR development in various genotypes and/or growth conditions is to determine LR density (the number of LRs and LRPs observed per unit length of the primary root) (28). Although this method provides insight into the development of an LRP based on cellular morphology, it cannot provide information regarding prebranch sites, because they are defined by expression of the pDR5:Luciferase ( pDR5:LUC) reporter gene and thought to occur before morphological changes (12).…”

Section: Resultsmentioning

confidence: 99%

“…Root, meristem, and cell lengths were measured from images of seedlings or confocal images using ImageJ software (National Institutes of Health). Roots were fixed and cleared using methods previously described (28), and LR/LRP number was examined under differential interference contrast illumination. In the LR capacity assay, the root tip is excised at 8 das and seedlings are grown for 3 more days; LRs and latestage LRPs are then counted under a dissecting microscope.…”

Section: Methodsmentioning

confidence: 99%

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Periodic root branching in Arabidopsis requires synthesis of an uncharacterized carotenoid derivative

Norman

Zhang

Cazzonelli

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

116

120

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In plants, continuous formation of lateral roots (LRs) facilitates efficient exploration of the soil environment. Roots can maximize developmental capacity in variable environmental conditions through establishment of sites competent to form LRs. This LR prepattern is established by a periodic oscillation in gene expression near the root tip. The spatial distribution of competent (prebranch) sites results from the interplay between this periodic process and primary root growth; yet, much about this oscillatory process and the formation of prebranch sites remains unknown. We find that disruption of carotenoid biosynthesis results in seedlings with very few LRs. Carotenoids are further required for the output of the LR clock because inhibition of carotenoid synthesis also results in fewer sites competent to form LRs. Genetic analyses and a carotenoid cleavage inhibitor indicate that an apocarotenoid, distinct from abscisic acid or strigolactone, is specifically required for LR formation. Expression of a key carotenoid biosynthesis gene occurs in a spatially specific pattern along the root's axis, suggesting spatial regulation of carotenoid synthesis. These results indicate that developmental prepatterning of LRs requires an uncharacterized carotenoid-derived molecule. We propose that this molecule functions non-cell-autonomously in establishment of the LR prepattern.root development | patterning | secondary metabolite synthesis A nchorage and uptake of water and soluble nutrients are essential functions of plant root systems and key to plant productivity and survival. The capacity of a root system to carry out these functions can be maximized by iterative root branching. Root branches are formed de novo during primary root growth, which allows for the elaboration of a complex root system that effectively enables the plant to navigate and exploit the resources of diverse, locally variable subterranean environments. Understanding the developmental mechanisms underlying the pattern of root branches has broad significance in both basic and applied research.As with other dicotyledonous plants, formation of a complex root system in the model plant Arabidopsis thaliana (Arabidopsis) occurs through iterative production of branches, or lateral roots (LRs), from the primary root. The simplified root system of Arabidopsis has yielded considerable insight into the cellular events and molecular regulators required for LR formation (recently reviewed in refs.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Periodic root branching in Arabidopsis requires synthesis of an uncharacterized carotenoid derivative

Norman

Zhang

Cazzonelli

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

116

120

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“…Even when it occurs in an acropetal sequence, as in Arabidopsis and barley, the precise timing and positioning of LR initiation is difficult to predict [8]. Auxin-based LR induction systems avoid this issue by triggering synchronized LR initiation over almost the whole primary root [9].…”

Section: Discussion (A) a Novel System For Monitoring Early Events Ofmentioning

confidence: 99%

“…The molecular analysis of the early stages of LR initiation is hampered by the fact that initiation occurs at positions and with a timing that are difficult to predict [8]. In addition, the morphological consequences of a mutation (or treatment) affecting early events only amount to a lack or reduction of LR initials.…”

Section: Introductionmentioning

confidence: 99%

Repression of early lateral root initiation events by transient water deficit in barley and maize

Babé

Lavigne

Séverin

et al. 2012

Phil. Trans. R. Soc. B

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The formation of lateral roots (LRs) is a key driver of root system architecture and developmental plasticity. The first stage of LR formation, which leads to the acquisition of founder cell identity in the pericycle, is the primary determinant of root branching patterns. The fact that initiation events occur asynchronously in a very small number of cells inside the parent root has been a major difficulty in the study of the molecular regulation of branching patterns. Inducible systems that trigger synchronous lateral formation at predictable sites have proven extremely valuable in Arabidopsis to decipher the first steps of LR formation. Here, we present a LR repression system for cereals that relies on a transient water-deficit treatment, which blocks LR initiation before the first formative divisions. Using a time-lapse approach, we analysed the dynamics of this repression along growing roots and were able to show that it targets a very narrow developmental window of the initiation process. Interestingly, the repression can be exploited to obtain negative control root samples where LR initiation is absent. This system could be instrumental in the analysis of the molecular basis of drought-responsive as well as intrinsic pathways of LR formation in cereals.

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“…20,21 LR primordia (LRP) further develop within the main root, reaching maturity soon after emergence. 22,23 LR initiation, development and emergence seem to be specific stages of an otherwise continuous process as regards the origin of auxin supply.…”

Section: Auxin Promotes While Ck Inhibits Lr Initiation and Developmentmentioning

confidence: 99%

Spatiotemporal aspect of cytokinin-auxin interaction in hormonal regulation of the root meristem

Kuderová

Hejátko²

2009

Plant Signaling & Behavior

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Lateral Root Initiation in Arabidopsis: Developmental Window, Spatial Patterning, Density and Predictability

Cited by 168 publications

References 51 publications

Periodic root branching in Arabidopsis requires synthesis of an uncharacterized carotenoid derivative

Periodic root branching in Arabidopsis requires synthesis of an uncharacterized carotenoid derivative

Repression of early lateral root initiation events by transient water deficit in barley and maize

Spatiotemporal aspect of cytokinin-auxin interaction in hormonal regulation of the root meristem

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