Cytokinin‐gibberellin Regulation of Shoot Development and Leaf Form in Tobacco Plantlets

Engelke, Alvin L.; Hamzi, Hamzi Q.; Skoog, Folke

doi:10.1002/j.1537-2197.1973.tb05949.x

Cited by 33 publications

(4 citation statements)

References 15 publications

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“…Here we identify positive regulation of GA as one way by which LA‐like factors promote differentiation. GA is known to promote tissue expansion and differentiation (Engelke et al. , 1973; Peng et al.…”

Section: Discussionmentioning

confidence: 99%

Gibberellin partly mediates LANCEOLATE activity in tomato

et al. 2011

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Elaboration of a compound leaf shape depends on extended morphogenetic activity in developing leaves. In tomato (Solanum lycopersicum), the CIN-TCP transcription factor LANCEOLATE (LA) promotes leaf differentiation. LA is negatively regulated by miR319 during the early stages of leaf development, and decreased sensitivity of LA mRNA to miR319 recognition in the semi-dominant mutant La leads to prematurely increased LA expression, precocious leaf differentiation and a simpler and smaller leaf. Increased levels or responses of the plant hormone gibberellin (GA) in tomato leaves also led to a simplified leaf form. Here, we show that LA activity is mediated in part by GA. Expression of the SlGA20 oxidase1 (SlGA20ox1) gene, which encodes an enzyme in the GA biosynthesis pathway, is increased in gain-of-function La mutants and reduced in plants that over-express miR319. Conversely, the transcript levels of the GA deactivation gene SlGA2 oxidase4 (SlGA2ox4) are increased in plants over-expressing miR319. The miR319 over-expression phenotype is suppressed by exogenous GA application and by a mutation in the PROCERA (PRO) gene, which encodes an inhibitor of the GA response. SlGA2ox4 is expressed in initiating leaflets during early leaf development. Its expression expands as a result of miR319 over-expression, and its over-expression leads to increased leaf complexity. These results suggest that LA activity is partly mediated by positive regulation of the GA response, probably by regulation of GA levels.

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Section: Discussionmentioning

confidence: 99%

Gibberellin partly mediates LANCEOLATE activity in tomato

et al. 2011

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“…Endogenous gibberellin levels are correlated with leaf size and shape in pea ( Ross, Murfet & Reid 1993) and tomato ( Nagel 1998). Exogenous cytokinin and gibberellin both stimulate cell expansion ( Engelke, Hamzi & Skoog 1973), but neither acts via an ‘acid‐growth’ mechanism in bean leaves ( Brock & Cleland 1989). Abscisic acid inhibits leaf expansion, perhaps by interacting with potassium conductance and interfering with proton efflux ( Van Volkenburgh & Davies 1983; Bacon, Wilkinson & Davies 1998).…”

Section: Introductionmentioning

confidence: 99%

Leaf expansion – an integrating plant behaviour

Volkenburgh

1999

Plant Cell & Environment

198

126

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Leaves expand to intercept light for photosynthesis, to take up carbon dioxide, and to transpire water for cooling and circulation. The extent to which they expand is determined partly by genetic constraints, and partly by environmental conditions signalling the plant to expand more or less leaf surface area. Leaves have evolved sophisticated sensory mechanisms for detecting these cues and responding with their own growth and function as well as influencing a variety of whole‐plant behaviours. Leaf expansion itself is an integrating behaviour that ultimately determines canopy development and function, allocation of materials determining relative shoot : root volume, and the onset of reproduction. To understand leaf development, and in particular, how leaf expansion is regulated, we must know at the molecular level which biochemical processes accomplish cell growth. Physiological experimentation focusing on ion fluxes across the plasmamembrane is providing new molecular information on how light stimulates cell expansion in some dicotyledonous species. Genetic analyses in Arabidopsis, corn, and other species are rapidly generating a list of mutations and enzyme activities associated with leaf development and expansion. Combination of these approaches, using informed physiological interpretations of phenotypic variation will allow us in the future to identify genes encoding both the processes causing cell expansion, and the regulators of these events.

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“…In summarizing the early auxin investigations, these authors also concluded that all of the available data "fit in with the view that auxin causes elongation of leaf veins, while the growth of the mesophyll depends on other factors" (Went and Thimman, 1937). This idea that leaf development is controlled by chemically distinct vein growth factors or "caulocaline" and mesophyll growth factors or "phyllocaline" (Went, 1951) was supported by the observation that treatment with adenine (Bonner and Haagen-Smit, 1939) and cytokinins (Engelke et al, 1973) promoted mesophyll growth but not veinal growth. …”

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confidence: 98%

Auxin-Induced Epinasty of Tobacco Leaf Tissues (A Nonethylene-Mediated Response)

Keller

Volkenburgh

1997

Plant Physiology

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Auxin has long been thought to have only a limited role in the growth of leaves. Avery (1935) first reported that treatment of young tobacco (Nicotiana tabacum L.) leaves with auxin produced epinasty (dorsoconvex curvature) resulting from growth within the midrib and that auxin was without effect on the lateral veins and interveinal tissues. Went and Thimman (1937) also detected auxin-induced elongation growth of the midrib and the lateral veins and confirmed that auxin treatment failed to increase the surface of the mesophyll. In summarizing the early auxin investigations, these authors also concluded that all of the available data "fit in with the view that auxin causes elongation of leaf veins, while the growth of the mesophyll depends on other factors" (Went and Thimman, 1937). This idea that leaf development is controlled by chemically distinct vein growth factors or "caulocaline" and mesophyll growth factors or "phyllocaline" (Went, 1951) was supported by the observation that treatment with adenine (Bonner and Haagen-Smit, 1939) and cytokinins (Engelke et al., 1973) promoted mesophyll growth but not veinal growth.

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Cytokinin‐gibberellin Regulation of Shoot Development and Leaf Form in Tobacco Plantlets

Cited by 33 publications

References 15 publications

Gibberellin partly mediates LANCEOLATE activity in tomato

Gibberellin partly mediates LANCEOLATE activity in tomato

Leaf expansion – an integrating plant behaviour

Auxin-Induced Epinasty of Tobacco Leaf Tissues (A Nonethylene-Mediated Response)

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