Silica in Shoots of Higher Plants

Kaufman, Peter B.; Dayanandan, P.; Takeoka, Yoji; Bigelow, Wilbur C.; Jones, J. D.; Iler, R.

doi:10.1007/978-1-4612-5944-2_15

Cited by 90 publications

(40 citation statements)

References 42 publications

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“…SEM, environmental scanning electron microscope (ESEM) and TEM-EDX analyses showed that silica first precipitates in the inner cell wall, probably triggered by the presence of callose or lignin (Laue et al, 2007;Law and Exeley, 2011;Zhang et al, 2013). Silica nanospheres are then organized in a variety of structural motifs such as sheet-like, globular and fibrillar bundles that, from the cell wall, infill the cell lumen in a centripetal way (e.g., Kaufman et al, 1981;Sangster and Parry, 1981;Perry et al, 1987;Laue et al, 2007;Zhang et al, 2013), until most of the cell becomes silicified (Motomura, 2004;Laue et al, 2007). As previously noted, an organic template may participate to the silica formation Harrison, 1996;Laue et al, 2007).…”

Section: Implications Regarding Phytc Occlusion and Phytc Accessibilitymentioning

confidence: 99%

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

et al. 2015

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Abstract. Phytoliths contain occluded organic compounds called phytC. Recently, phytC content, nature, origin, paleoenvironmental meaning and impact in the global C cycle have been the subject of increasing debate. Inconsistencies were fed by the scarcity of in situ characterizations of phytC in phytoliths. Here we reconstructed at high spatial resolution the 3-D structure of harvested grass short cell (GSC) phytoliths using 3-D X-ray microscopy. While this technique has been widely used for 3-D reconstruction of biological systems it has never been applied in high-resolution mode to silica particles. Simultaneously, we investigated the location of phytC using nanoscale secondary ion mass spectrometry (NanoSIMS). Our data evidenced that the silica structure contains micrometric internal cavities. These internal cavities were sometimes observed isolated from the outside. Their opening may be an original feature or may result from a beginning of dissolution of silica during the chemical extraction procedure, mimicking the progressive dissolution process that can happen in natural environments. The phytC that may originally occupy the cavities is thus susceptible to rapid oxidation. It was not detected by the NanoSIMS technique. However, another pool of phytC, continuously distributed in and protected by the silica structure, was observed. Its N / C ratio (0.27) is in agreement with the presence of amino acids. These findings constitute a basis to further characterize the origin, occlusion process, nature and accessibility of phytC, as a prerequisite for assessing its significance in the global C cycle.

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Section: Implications Regarding Phytc Occlusion and Phytc Accessibilitymentioning

confidence: 99%

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

et al. 2015

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“…Application of GA3 results in acidification of the medium by excised stem segments (1 1) and also blocks silica deposition in the basal portion of the internode [part of which is geosensitive (23)]. The node-pulvinus is also relatively unsilicified (7,14). The node-pulvinus and the internode base are also relatively free of lignin (except in tracheary elements) (7).…”

Section: Effects Of Geostimulation On the Distribution Of Dry Mattermentioning

confidence: 99%

Changes in Endogenous Gibberellins and the Metabolism of [³H]GA₄ after Geostimulation in Shoots of the Oat Plant (Avena sativa)

Pharis¹,

Legge²,

Noma³

et al. 1981

Plant Physiol.

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The recovery from "lodging," or bending over, by shoots of 42-day-old Avena sativa plants is controlled primarily by a negatively geotropic differential growth of the lower halves of the p-I node-pulvinus and the base of the p-I internode, relative to the upper halves. Although geostimulation causes a significant reduction in p-1 internode length, dry matter accumulation in the p-i node-pulvinus is increased, apparently at the expense of the sheath. Recovery to an angle of 300 is associated with changes in endogenous gibberellin-like substances (GAs), and in differential metabolism of applied I3HIGA4 (1.4 Curie per millimole). Although geostimulation depressed total GAs (relative to upright plant parts) to 0.40 and 0.13 for node-pulvini and sheaths, respectively, it increased them 2-fold for internodes. Within the plant part geostimulation increased GAs (relative to upper halves) 29-and 7-fold in lower halves of node-pulvini and internodes, respectively, but reduced GAs to 0.3 in lower halves of sheaths. At age 42 days a GA4/7-like (nonpolar) substance predominates, with lesser amounts of a GA3-llke (polar) substance. Native GAs of Avena include GA3, GA4, and GA7. Geostimulation enhanced the ratio of nonpolar to polar GAs for both halves of internodes, but tended to depress it for sheaths and nodepulvini.The disposition and metabolism of applied 13HIGA4 confirmed the above trends for endogenous GAs regarding localization (e.g. up to 2-fold increases in 13HIGA4 and acidic 3H-metabolites in the lower halves, relative to upper halves). Also, metabolism into highly water-soluble 3H-metabolites (biologically jnactive conjugates?) was greater (up to 1.8-fold) in upper than in lower halves. The end result of such metabolic trends would be to reduce acidic (biologically active?) GAs in the upper half, while retaining them for a longer time in the lower half.Geotropically stimulated Avena shoots thus increase, within 24 hours, the levels of acidic GAs in the lower halves of the p-1 node-pulvinus and p-I internode, the two plant parts responsible for the geostimulated growth.

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“…Large amounts of silicon are deposited in the cell walls of grasses (Poaceae), particularly in the walls ofspecialized epidermal cells of the shoot (11,12). Greatest concentrations of silicon in sugarcane (Saccharum spp.)…”

Section: Introductionmentioning

confidence: 99%

“…The close correlation between increase in growth of an internode in response to gibberellic acid and the decrease in silcon content of that internode indicated a dilution effect of growth on the amount of silicon rather than a direct effect of gibberellic acid on silicon deposition. This conclusion was supported by sca electrom microscopy, X-ray map photos, and counts of silica cells per unit of epidermis area.Large amounts of silicon are deposited in the cell walls of grasses (Poaceae), particularly in the walls ofspecialized epidermal cells of the shoot (11,12). Greatest concentrations of silicon in sugarcane (Saccharum spp.)…”

mentioning

confidence: 99%

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Effect of Gibberellic Acid on Silica Content and Distribution in Sugarcane

Kaufman

Ghosheh²,

Lee³

et al. 1981

Plant Physiol.

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The effect of gibberellic acid on the content and distribution of silicon in the stem, leaf sheath, and leaf lamina of sugarcane was analyzed in relation to the effect of gibberelUc acid on stem growth. Silicon content was measured by neutron activation analysis, and its distribution was foDlowed by scanning electron microscopy and X-ray analysis.Foliarly appled gibberellic acid increased stem length and fresh weight and decreased silicon content. Gibberelic acid treatments had lttle or no effect on growth or silcon content of leaf laminae or sheaths. The close correlation between increase in growth of an internode in response to gibberellic acid and the decrease in silcon content of that internode indicated a dilution effect of growth on the amount of silicon rather than a direct effect of gibberellic acid on silicon deposition. This conclusion was supported by sca electrom microscopy, X-ray map photos, and counts of silica cells per unit of epidermis area.Large amounts of silicon are deposited in the cell walls of grasses (Poaceae), particularly in the walls ofspecialized epidermal cells of the shoot (11,12). Greatest concentrations of silicon in sugarcane (Saccharum spp.) occur in the inner tangential walls of the root endodermis (15) and in the silica cells of the leaf and stem epidermis (2,18,19). The percentage of silicon in shoot tissue is relatively high in sugarcane and is known to vary with plant age (3), season (7), soil silicate content (8), and species or cultivar (2).In sugarcane, low silicon has been associated with deficiency symptoms, primarily leaf freckling (4, 18, 19), reduced photosynthesis (18,19), and reduced yields (5,8). Silicate amendments to the soil decrease leaf freckling (4,18,19) and increase tissue silicon (7) and yields (5,16). The association of increased tissue silicon with increased enzyme activities, photosynthetic rates, and sugar yields prompted some investigators to propose essentially biochemical roles for silicon in sugarcane metabolism (1,18,19 be injurious to the roots, and the shoots of sugarcane to be the primary site of action of silicon (5, 16).GA3 increases growth and yields but decreases the percentage of silicon in affected tissues (13). GA3 also reduces the percentage of silicon in Avena internodes, probably as a consequence of the increase in cell volume (17). In contrast, Neumann and Janiossy (14) found that GA3 significantly increased the silicon content of cell walls in di dwarf mutant of corn (Zea mays). When silicon in GA3-treated sugarcane is low, it is not known if the decrease is the result of dilution due to GArstimulated growth, reduction in the number ofsilica cells per organ, or a reduction in the concentration of silicon per cell. The purpose of the experiments reported here was to determine the effect of GA3-stimulated growth on the quantity of silicon in vegetative shoot organs (leaf laminae, leaf sheaths, and internodes) and on the distribution of silicon in the shoot epidermis of sugarcane.MATERIALS AND METHODS Plant Material. Tissue ...

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Silica in Shoots of Higher Plants

Cited by 90 publications

References 42 publications

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

Changes in Endogenous Gibberellins and the Metabolism of [³H]GA₄ after Geostimulation in Shoots of the Oat Plant (Avena sativa)

Effect of Gibberellic Acid on Silica Content and Distribution in Sugarcane

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Silica in Shoots of Higher Plants

Cited by 90 publications

References 42 publications

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results

Changes in Endogenous Gibberellins and the Metabolism of [3H]GA4 after Geostimulation in Shoots of the Oat Plant (Avena sativa)

Effect of Gibberellic Acid on Silica Content and Distribution in Sugarcane

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Changes in Endogenous Gibberellins and the Metabolism of [³H]GA₄ after Geostimulation in Shoots of the Oat Plant (Avena sativa)