Branching Out in Roots: Uncovering Form, Function, and Regulation

Atkinson, Jonathan A.; Rasmussen, Amanda; Traini, Richard; Voß, Ute; Sturrock, Craig J.; Mooney, Sacha J.; Wells, Darren M.; Bennett, Malcolm J.

doi:10.1104/pp.114.245423

Cited by 225 publications

(180 citation statements)

References 106 publications

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“…These rhizoids can be considered to be analogous to the adventitious roots produced from the stems of some land plants (Atkinson et al, 2014). The dis-1 and dis-2 mutants failed to produce secondary rhizoids during both the sporophyte and the gametophyte generations.…”

Section: Results Dis Mutants Lack a Basal Systemmentioning

confidence: 99%

DISTAG/TBCCd1 Is Required for Basal Cell Fate Determination in Ectocarpus

et al. 2017

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Brown algae are one of the most developmentally complex groups within the eukaryotes. As in many land plants and animals, their main body axis is established early in development, when the initial cell gives rise to two daughter cells that have apical and basal identities, equivalent to shoot and root identities in land plants, respectively. We show here that mutations in the Ectocarpus DISTAG (DIS) gene lead to loss of basal structures during both the gametophyte and the sporophyte generations. Several abnormalities were observed in the germinating initial cell in dis mutants, including increased cell size, disorganization of the Golgi apparatus, disruption of the microtubule network, and aberrant positioning of the nucleus. DIS encodes a TBCCd1 protein, which has a role in internal cell organization in animals, Chlamydomonas reinhardtii, and trypanosomes. Our study highlights the key role of subcellular events within the germinating initial cell in the determination of apical/basal cell identities in a brown alga and emphasizes the remarkable functional conservation of TBCCd1 in regulating internal cell organization across extremely distant eukaryotic groups.

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Section: Results Dis Mutants Lack a Basal Systemmentioning

confidence: 99%

DISTAG/TBCCd1 Is Required for Basal Cell Fate Determination in Ectocarpus

et al. 2017

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“…Root elongation and branching are iterative processes in root development (Malamy and Benfey, 1997;Nibau et al, 2008;Atkinson et al, 2014). Variations in the attributes of elongation and branching create morphological differences in the lengths, numbers and diameters of different-order roots within the root system (Fitter, 1987;Gruber et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Relationships between root diameter, root length and root branching along lateral roots in adult, field-grown maize

Pagès

2016

Ann Bot

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Background and Aims Root diameter, especially apical diameter, plays an important role in root development and function. The variation in diameter between roots, and along roots, affects root structure and thus the root system's overall foraging performance. However, the effect of diameter variation on root elongation, branching and topological connections has not been examined systematically in a population of high-order roots, nor along the roots, especially for mature plants grown in the field.Methods A method combining both excavation and analysis was applied to extract and quantify root architectural traits of adult, field-grown maize plants. The relationships between root diameter and other root architectural characteristics are analysed for two maize cultivars.Key Results The basal diameter of the lateral roots (orders 1-3) was highly variable. Basal diameter was partly determined by the diameter of the bearing segment. Basal diameter defined a potential root length, but the lengths of most roots fell far short of this. This was explained partly by differences in the pattern of diameter change along roots. Diameter tended to decrease along most roots, with the steepness of the gradient of decrease depending on basal diameter. The longest roots were those that maintained (or sometimes increased) their diameters during elongation. The branching density (cm -1 ) of laterals was also determined by the diameter of the bearing segment. However, the location of this bearing segment along the mother root was also involved -intermediate positions were associated with higher densities of laterals.Conclusions The method used here allows us to obtain very detailed records of the geometry and topology of a complex root system. Basal diameter and the pattern of diameter change along a root were associated with its final length. These relationships are especially useful in simulations of root elongation and branching in source-sink models.

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“…Root structure is highly adaptive. It is shaped by environmental signals such as gravity, light, nutrients, and water availability to ensure plant survival and propagation (Atkinson et al, 2014;Bellini et al, 2014). Gravity is an invariant physical signal and, hence, well suited to provide spatial orientation for plants.…”

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confidence: 99%

Control of Adventitious Root Architecture in Rice by Darkness, Light, and Gravity

Lin

Sauter

2017

Plant Physiol.

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ORCID IDs: 0000-0002-3607-6133 (C.L.); 0000-0002-7370-643X (M.S.).Rice (Oryza sativa) is a semiaquatic plant that is well adapted to partial flooding. Rice stems develop adventitious root (AR) primordia at each node that slowly mature but emerge only when the plant gets flooded, leading to the formation of a whole new secondary root system upon flooding. AR growth is induced by ethylene that accumulates in submerged plant tissues due to its lowered diffusion rate in water. Here, we report that the architecture of the secondary root system in flooded rice plants is controlled not only by altered gas diffusion but also by gravity and light. While ethylene promotes the emergence and growth of ARs, gravity and light determine their gravitropic setpoint angle (i.e. the deviation of growth direction relative to vertical). ARs grow upward at about 120°in the dark and downward at 54°in the light. The upward growth direction is conserved in indica and japonica rice varieties, suggestive of a conserved trait in rice. Experiments with a klinostat and with inverted stem orientation revealed that gravity promotes upward growth by about 10°. Red, far-red, and blue light lead to negative phototropism in a dose-dependent manner, with blue light being most effective, indicating that phytochrome and blue light signaling control AR system architecture. The cpt1 (coleoptile phototropism1) mutant, which lacks one of the phototropin-interacting CPT proteins, shows reduced sensitivity to blue light. Hence, the gravitropic setpoint angle of rice ARs is controlled by genetic and environmental factors that likely balance the need for oxygen supply (upward growth) with avoidance of root desiccation (downward growth).

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Branching Out in Roots: Uncovering Form, Function, and Regulation

Cited by 225 publications

References 106 publications

DISTAG/TBCCd1 Is Required for Basal Cell Fate Determination in Ectocarpus

DISTAG/TBCCd1 Is Required for Basal Cell Fate Determination in Ectocarpus

Relationships between root diameter, root length and root branching along lateral roots in adult, field-grown maize

Control of Adventitious Root Architecture in Rice by Darkness, Light, and Gravity

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