Root gravitropism: a complex response to a simple stimulus?

Rosen, Elizabeth; Chen, Rujin; Masson, Patrick

doi:10.1016/s1360-1385(99)01472-7

Cited by 71 publications

(33 citation statements)

References 43 publications

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“…studies have already established its presence and some of its characteristics (Okada and Shimura, 1990;Buer et al, 2000;Migliaccio and Piconese, 2001)-but rather to explore its evolution in time. Information of the kind provided by this study is critical if we are to properly parse the different physical forces involved in root waving, as well as interpret and predict the effects of relevant genetic lesions in auxin or cell wall biochemistry (Marinelli et al, 1997;Mullen et al, 1998b;Rosen et al, 1999).…”

Section: Discussion the Potential Importance Of Root-gel Interactionsmentioning

confidence: 99%

“…And why at 0°, in the absence of any effectual lateral gravitropic bias, does the root not simply meander? While the overall downward trajectory of the root is clearly a gravitropic effect, as corroborated by studies of auxin-deficient or gravitropism-impaired mutants (Okada and Shimura, 1990;Simmons et al, 1995a;Rutherford and Masson, 1996;Mullen et al, 1998b;Rosen et al, 1999;Migliaccio and Piconese, 2001;Massa and Gilroy, 2003), why the root should turn at all-that is, what causes root tip deflection?-is still debated. A variety of deflecting forces have been proposed, including thigmotropism (Okada and Shimura, 1990), circumnutation (Simmons et al, 1995b;Rutherford and Masson, 1996;Migliaccio and Piconese, 2001), and, as mentioned above, the coupling that occasionally existed between root twisting, coiling and slanting.…”

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confidence: 99%

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Root-Gel Interactions and the Root Waving Behavior of Arabidopsis

2004

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Arabidopsis roots grown on inclined agarose gels exhibit a sinusoidal growth pattern known as root waving. While root waving has been attributed to both intrinsic factors (e.g. circumnutation) and growth responses to external signals such as gravity, the potential for physical interactions between the root and its substrate to influence the development of this complex phenotype has been generally ignored. Using a rotating stage microscope and time-lapse digital imaging, we show that (1) root tip mobility is impeded by the gel surface, (2) this impedance causes root tip deflections by amplifying curvature in the elongation zone in a way that is distinctly nontropic, and (3) root tip impedance is augmented by normal gravitropic pressure applied by the root tip against the gel surface. Thus, both lateral corrective bending near the root apex and root tip impedance could be due to different vector components of the same graviresponse. Furthermore, we speculate that coupling between root twisting and bending is a mechanical effect resulting from root tip impedance.

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Section: Discussion the Potential Importance Of Root-gel Interactionsmentioning

confidence: 99%

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confidence: 99%

Root-Gel Interactions and the Root Waving Behavior of Arabidopsis

2004

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“…Plastid differentiation to amyloplasts in columella cells has also been well described. In these cells, there is a progressive accumulation of apparently non-polarized starch containing organelles to the formation of basally-located amyloplasts (Blancaflor et al, 1998;Rosen et al, 1999;Van Den Berg et al, 1997;Wildwater et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Analysis of chlorophyll fluorescence reveals stage specific patterns of chloroplast-containing cells during Arabidopsis embryogenesis

2010

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The basic body plan of a plant is established early in embryogenesis when cells differentiate, giving rise to the apical and basal regions of the embryo. Using chlorophyll fluorescence as a marker for chloroplasts, we have detected specific patterns of chloroplast-containing cells at specific stages of embryogenesis. Nonrandomly distributed chloroplast-containing cells are seen as early as the globular stage of embryogenesis in Arabidopsis. In the heart stage of embryogenesis, chloroplast containing cells are detected in epidermal cells as well as a central region of the heart stage embryo, forming a triangular septum of chloroplast-containing cells that divides the embryo into three equal sectors. Torpedo stage embryos have chloroplast-containing epidermal cells and a central band of chloroplast-containing cells in the cortex layer, just below the shoot apical meristem. In the walking-stick stage of embryogenesis, chloroplasts are present in the epidermal, cortex and endodermal cells. The chloroplasts appear reduced or absent from the provascular and columella cells of walking-stick stage embryos. These results suggest that there is a tight regulation of plastid differentiation during embryogenesis that generates specific patterns of chloroplast-containing cells in specific cell layers at specific stages of embryogenesis.

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“…Amyloplasts are found in specialized cells, such as the starch parenchyma surrounding the vascular tissue in plant shoots and grass pulvini, and in the columella of the root cap (Sack, 1991;Chen et al, 1999;Rosen et al, 1999;Perrin et al, 2005). Upon reorientation of a plant shoot or root, the settling of amyloplasts, or the pressure exerted by protoplast settlement (Staves, 1997), is thought to trigger intra-and intercellular signaling, initiating downstream metabolic changes, including a lateral redistribution of auxin, leading to an asymmetric growth response (Lomax et al, 1995;Muday and DeLong, 2001).…”

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A Universal Role for Inositol 1,4,5-Trisphosphate-Mediated Signaling in Plant Gravitropism

et al. 2005

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Inositol 1,4,5-trisphosphate (InsP 3 ) has been implicated in the early signaling events of plants linking gravity sensing to the initiation of the gravitropic response. However, at present, the contribution of the phosphoinositide signaling pathway in plant gravitropism is not well understood. To delineate the role of InsP 3 in plant gravitropism, we generated Arabidopsis (Arabidopsis thaliana) plants constitutively expressing the human type I inositol polyphosphate 5-phosphatase (InsP 5-ptase), an enzyme that specifically hydrolyzes InsP 3 . The transgenic plants show no significant differences in growth and life cycle compared to wild-type plants, although basal InsP 3 levels are reduced by greater than 90% compared to wild-type plants. With gravistimulation, InsP 3 levels in inflorescence stems of transgenic plants show no detectable change, whereas in wild-type plant inflorescences, InsP 3 levels increase approximately 3-fold within the first 5 to 15 min of gravistimulation, preceding visible bending. Furthermore, gravitropic bending of the roots, hypocotyls, and inflorescence stems of the InsP 5-ptase transgenic plants is reduced by approximately 30% compared with the wild type. Additionally, the cold memory response of the transgenic plants is attenuated, indicating that InsP 3 contributes to gravisignaling in the cold. The transgenic roots were shown to have altered calcium sensitivity in controlling gravitropic response, a reduction in basipetal indole-3-acetic acid transport, and a delay in the asymmetric auxin-induced b-glucuronidase expression with gravistimulation as compared to the controls. The compromised gravitropic response in all the major axes of growth in the transgenic Arabidopsis plants reveals a universal role for InsP 3 in the gravity signal transduction cascade of plants.

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Root gravitropism: a complex response to a simple stimulus?

Cited by 71 publications

References 43 publications

Root-Gel Interactions and the Root Waving Behavior of Arabidopsis

Root-Gel Interactions and the Root Waving Behavior of Arabidopsis

Analysis of chlorophyll fluorescence reveals stage specific patterns of chloroplast-containing cells during Arabidopsis embryogenesis

A Universal Role for Inositol 1,4,5-Trisphosphate-Mediated Signaling in Plant Gravitropism

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