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Internodal elongation and orientation of cellulose microfibrils and microtubules in deepwater rice (1993)

Sauter, Margret ; Seagull, Robert W. ; Kende, Hans

Springer

Planta 190 (1993), S. 354-362

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ISSN: 1432-2048

Keywords: Cellulose microfibril ; Gibberellin ; Internodal elongation ; Microtubule ; Oryza (growth)

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Excised stem sections of deepwater rice (Oryza sativa L.) containing the highest internode were used to study the induction of rapid internodal elongation by gibberellin (GA). It has been shown before that this growth response is based on enhanced cell division in the intercalary meristem and on increased cell elongation. In both GA-treated and control stem sections, the basal 5-mm region of the highest internode grows at the fastest rate. During 24 h of GA treatment, the internodal elongation zone expands from 15 to 35 mm. Gibberellin does not promote elongation of internodes from which the intercalary meristem has been excised. The orientation of cellulose microfibrils (CMFs) is a determining factor in cell growth. Elongation is favored when CMFs are oriented transversely to the direction of growth while elongation is limited when CMFs are oriented in the oblique or longitudinal direction. The orientation of CMFs in parenchymal cells of GA-treated and control internodes is transverse throughout the internode, indicating that CMFs do not restrict elongation of these cells. Changes in CMF orientation were observed in epidermal cells, however. In the basal 5-mm zone of the internode, which includes the intercalary meristem, CMFs of the epidermal cell walls are transversely oriented in both GA-treated and control stem sections. In slowly growing control internodes, CMF orientation changes to the oblique as cells are displaced from this basal 5-mm zone to the region above it. In GA-treated rapidly growing internodes, the reorientation of CMFs from the transverse to the oblique is more gradual and extends over the 35-mm length of the elongation zone. The CMFs of older epidermal cells are obliquely oriented in control and GA-treated internodes. The orientation of the CMFs parallels that of the cortical microtubules. This is consistent with the hypothesis that cortical microtubules determine the direction of CMF deposition. We conclude that GA acts on cells that have transversely oriented CMFs but does not promote growth of cells whose CMFs are already obliquely oriented at the start of GA treatment.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00196964

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Effects of taxol on microtubule arrays in cultured higher plant cells (1986)

Weerdenburg, Carol ; Falconer, Marcia M. ; Setterfield, George ; [et al.]

New York, NY : Wiley-Blackwell

Cell Motility and the Cytoskeleton 6 (1986), S. 469-478

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ISSN: 0886-1544

Keywords: plant microtubules ; mitosis ; cytokinesis ; plant cell culture ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Treatment with 10 μm taxol disrupted mitotic and cytoplasmic arrays of microtubules (MT) in cultured cells of two higher plants, Vicia hajastana (vetch) and Zinnia elegans. When treated for 1, 24, and 48 h, cells in both cultures showed similar effects. After 1 h, multipolar arrays of MT were noted in prophase, large aster-like arrays of MT appeared in metaphase, and extra MT shared poles with otherwise normal-appearing metaphase and anaphase configurations. After 24 and 48 h, some phragmoplasts were multipartite or misplaced. In interphase cells, micronuclei and multinucleate cells were evidence of irregular mitosis and cytokinesis. Cytoplasmic MT in elongated cells were oriented parallel to, instead of at right angles to the long axis of the cell. Some interphase cells lost asymmetry while maintaining organized arrays of MT. Taxol appears to disrupt mitotic and cytoplasmic arrays of MT, seemingly overriding the mechanism(s) regulating MT polymerization and orientation.

Additional Material: 5 Ill.