Gibberellin does not accelerate rates of cell division in the dwarf pea shoot apical meristem

Daykin, Alison; Scott, Ian M.; Causton, D. R.; Francis, Dennis

doi:10.1093/jxb/48.5.1147

Cited by 11 publications

(8 citation statements)

References 10 publications

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“…It therefore appears that the growth response of dwarf pea stems to GA 3 must occur within the developing internodes. This is consistent with our recent report that GA 3 does not accelerate the cell cycle in the dwarf pea apical meristem (Daykin et al 1997), and with other physiological experiments on dwarf peas (Arney and Mancinelli 1967;Yang et al 1996). Studies on other dicotyledonous species have also located the major growth eects of GA 3 below the apex (Sachs 1965;Besnard-Wibaut et al 1983;Edelman and Loy 1987;Talon et al 1991).…”

Section: Resultssupporting

confidence: 94%

“…Thus, no morphological eects of GA 3 were detected on the newly formed internodes in the youngest regions of the apex. This is consistent with the absence of a GA 3 -stimulating eect on cell division in the apical dome or sub-apical region at this time (Daykin et al 1997).…”

Section: Resultssupporting

confidence: 90%

“…Table 2 shows that the CDTs estimated for the +GA 3 plants were half or less than those in the AGA 3 plants ( Table 2). The CDTs in the AGA 3 tissues were comparable to estimates of 37±40 h for CDTs in the apical meristem of dwarf peas (Daykin et al 1997).…”

Section: Resultssupporting

confidence: 69%

“…A small cut was placed at the top of each segment to facilitate correct orientation. The samples were embedded in paran wax, and longitudinal sections (10 lm) were cut and stained by the Feulgen reaction and counter-stained with Fast Green (Daykin et al 1997).…”

Section: Methodsmentioning

confidence: 99%

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Effects of gibberellin on the cellular dynamics of dwarf pea internode development

Daykin

Scott

Francis

et al. 1997

Planta

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This study analysed the dynamics of cell production and extension, and how these were aected by applied gibberellic acid (GA 3 ), during internode development in dwarf peas (Pisum sativum L. cv. Meteor). Image analysis was used to obtain cell number and length data for entire cell columns along the epidermis, the two outermost cortical layers, and the pith, from internode 7, over a time period covering the whole of the internode's growth phase. For a few days following the inception of an internode at the shoot apex, little further growth occurred, and there was no signi®cant eect of GA 3 on cell division or cell extension. The subsequent growth of the internode was stimulated more than fourfold by GA 3 as a result of the production of more than twice the number of cells, which were twice as long. At least 96.5% of the cells of the mature internode were actually formed within the internode itself during this period of growth, demonstrating that the internode cells themselves represent the morphogenetic site of response to GA 3 . Mitoses and cell extension occurred along the full length of the internode throughout its development. The daily changes in cell numbers were modelled by the Richards function, and manipulations of the ®tted functions to reveal time trends of absolute and speci®c cell production rates were performed for each stem tissue. The increase in cell numbers in the +GA 3 plants was brought about by an increase in the rate of cell production, over a shorter time interval; speci®c cell production rates declined continuously from initial rapid rates in the +GA 3 epidermis and pith, but declined more slowly in the cortex. The control (AGA 3 ) epidermis and cortex cells exhibited a constant speci®c cell production rate (i.e. purely exponential) for several days. Cell extension rates were calculated so as to compensate for the size-reduction eects of concurrent cell division. These calculations con®rmed that`real' cell extension rates were higher in the +GA 3 internodes. Models of the cellular controls of internode growth, based on the estimated dynamics of cell division and extension, are discussed.Abbreviations: ANOVA = analysis of variance; CDT = cell doubling time; GA 3 = gibberellic acid Correspondence to: I.M. Scott;

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Section: Resultssupporting

confidence: 94%

Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 69%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Effects of gibberellin on the cellular dynamics of dwarf pea internode development

Daykin

Scott

Francis

et al. 1997

Planta

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show abstract

“…GA3-treated C. fimbriatum plants did not exhibit significant changes in stolon dry matter accumulation (data not shown), which indirectly suggest that this hormone should be acting mainly on cell elongation rather than on apical meristem activity. Although stimulatory effects of gibberellin has been observed on cell division of dwarf pea apical meristems (Daykin et al, 1997), the maintenance of an active meristem in the PA-treated C. fimbriatum plants suggests that the meristem activity in this orchid does not depend on this hormone (Fig. 4).…”

Section: Article In Pressmentioning

confidence: 96%