Genetic Analysis of the Role of Gibberellin in the Red Light Inhibition of Stem Elongation in Etiolated Seedlings

Behringer, Friedrich J.; Davies, Peter J.; Reid, James B.

doi:10.1104/pp.94.2.432

Cited by 40 publications

(25 citation statements)

References 23 publications

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“…1). This is consistent with measurements that show that elongation in cv Torsdag is maximally inhibited about 3 h after exposure to continuous R light (Behringer et al, 1990). The reduction in shoot GA 1 concentration was maintained to the 24-h sample point, where the GA 1 level was 70 times less than found in WL-grown controls and more than eight times less than dark-grown controls (measured on a whole shoot basis).…”

Section: Changes In Ga Levels During De-etiolationsupporting

confidence: 78%

“…For example the growth rate of na (GA-deficient) plants in the dark is less than 20% of WT plants (Behringer et al, 1990). Brassinosteroid-deficient mutants of pea also have reduced growth rates in the dark (Behringer et al, 1990;Nomura et al, 1999). However, there is no evidence of a decrease in brassinosteroid levels after de-etiolation (L. Shultz, A. Symons, D. Gregory, and J. Reid, unpublished results).…”

Section: Discussionmentioning

confidence: 99%

“…This is consistent with the phenotypes of dark-grown WT GA-deficient plants. For example the growth rate of na (GA-deficient) plants in the dark is less than 20% of WT plants (Behringer et al, 1990). Brassinosteroid-deficient mutants of pea also have reduced growth rates in the dark (Behringer et al, 1990;Nomura et al, 1999).…”

Section: Discussionmentioning

confidence: 99%

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Changes in Gibberellin A1 Levels and Response during De-Etiolation of Pea Seedlings

2000

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The level of gibberellin A1 (GA1) in shoots of pea (Pisum sativum) dropped rapidly during the first 24 h of de-etiolation. The level then increased between 1 and 5 d after transfer to white light. Comparison of the metabolism of [13C3H] GA20 suggested that the initial drop in GA1 after transfer is mediated by a light-induced increase in the 2β-hydroxylation of GA1 to GA8. A comparison of the elongation response to GA1 at early and late stages of de-etiolation provided strong evidence for a change in GA1 response during de-etiolation, coinciding with the return of GA1 levels to the normal, homeostatic levels found in light- and dark-grown plants. The emerging picture of the control of shoot elongation by light involves an initial inhibition of elongation by a light-induced decrease in GA1 levels, with continued inhibition mediated by a light-induced change in the plant's response to the endogenous level of GA1. Hence the plant uses a change in hormone level to respond to a change in the environment, but over time, homeostasis returns the level of the hormone to normal once the ongoing change in environment is accommodated by a change in the response of the plant to the hormone.

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Section: Changes In Ga Levels During De-etiolationsupporting

confidence: 78%

Section: Discussionmentioning

confidence: 99%

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Changes in Gibberellin A1 Levels and Response during De-Etiolation of Pea Seedlings

2000

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“…An action spectrum for the response in Sinapis suggests that phytochrome controls responses to continuous light at both low (DRL) and high fluence rates (2), and farred reversibility of both responses has been shown in peas (3,14). The two different responses to different red-light fluence rates may be related to two different forms of phytochrome, one present in large quantities in etiolated seedlings (type I) and the other present in deetiolated plants (17,19,24).…”

Section: Resultsmentioning

confidence: 99%

Adaptation to Dim-Red Light Leads to a Nongradient Pattern of Stem Elongation in Cucumis Seedlings

Shinkle

Sooudi²,

Jones³

1992

Plant Physiol.

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Relative growth rate determinations on 5-millimeter regions of cucumber (Cucumis sativus L.) hypocotyls show that dim-red lightgrown seedlings have an even distribution of growth along the stem axis. This contrasts with the apical to basal graded decline in growth rate seen in dark-grown seedlings, including dark-grown cucumber seedlings used as controls in this study. Dark-grown seedlings convert to the nongradient pattern when transferred to dim-red light. The small amount of light required suggests that the change in developmental pattern may happen in the natural light environment.A consensus characteristic of stem elongation is a gradient of elongation rates along the stem axis, with high rates of elongation near the apex and a graded decline toward the base. Etiolation is characterized by rapid stem elongation exhibiting a graded pattern (8,9,23,25,28), whereas stem elongation following deetiolation is relatively slow but still exhibits the apical to basal gradient of extension rates (9,10,25). The hypothesis that changes in cell structure and function follow the gradient in growth rate has been tested for several developmental processes (23,25,28).Germinating cucumber (Cucumis sativus L.) seedlings in continuous DRL3 (21) MATERIALS AND METHODSCucumber seedlings (Cucumis sativus L. cv Burpee's pickler) were germinated in moist vermiculite and grown under DRL as described previously (21) or in a similar dark room at 24 ± 10C. Experiments were carried out in growth rooms at two locations (Berkeley, CA, and San Antonio, TX). For both locations, the DRL field in the growth room had fluence rates ranging from 0.3 to 0.5 ,Imol m-2 s-'. The light source for DRL emitted 90% of its total output between 600 and 700 nm, with peaks at 638 and 648 nm (13; data not shown).For determination of RGRs (18, 22), marks (carborundum chips, 100 ,um diameter) were placed at 5-mm intervals along hypocotyls of 3.5-to 4-d-old seedlings for total length of 40 to 60 mm. Seedlings were allowed to recover from handling for 2 h before data were taken. Video images were obtained from a Panasonic WV-1850 video camera (Matsushita Electronics, Seacaucus, NJ) that has a high sensitivity to red and IR light. Images of DRL-grown seedlings were obtained using light available in the DRL growth room. DG seedlings were imaged under photomorphogenetically inactive IR illumination (12). For marking and placement for imaging, DG seedlings were exposed to 1 to 2 min of green work light, which was previously shown not to affect growth in this cultivar (8). The images were processed by a personal computer running video digitizer board (Video-Van-Gough, Tekmatic Systems, Ben Lomond, CA) and programs used previously (18). The digitizer located the marks and recorded their position in x and y coordinates on an arbitrary scale. Region lengths were determined by calculating distances between marks and converting numbers from computer units to millimeters using a conversion factor established by measuring known distances. Marks were tracked for 2 h, ...

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“…At this time it is not possible to draw clear conclusions concerning the involveinent of GAs in phy action, and there is a possibility that fhe relationship is different for separate phy types or at different developmental stages. Physiological (Metzger, 1988) or genetic and physiological (Behringer et al, 1990) evidence has even suggested independent actions for phy and GAs.…”

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confidence: 99%

Phytochrome, Gibberellins, and Hypocotyl Growth (A Study Using the Cucumber (Cucumis sativus L.) long hypocotyl Mutant)

et al. 1995

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The possible involvement of gibberellins (CAs) in the regulation of hypocotyl elongation by phytochrome was examined. Under white light the tal1 long hypocotyl (Ih) cucumber (Cucumis sativus L.) mutant, deficient in a type B-like phytochrome, shows an increased "responsiveness" (defined as response capability) to applied CA, (the main endogenous active CA) compared to the wild type. Supplementing far-red irradiation results in a similar increase in responsiveness in the wild type. Experiments involving application of the precursor GA, and of an inhibitor of CA, inactivation suggest that both the GA, activation and inactivation steps are phytochrome independent. Endogenous C A levels of whole seedlings were analyzed by combined gas chromatography-mass spectrometry using deuterated interna1 standards. The levels of GA, (and those of CA,,, the inactivated CA,) were lower in the //I mutant under low-irradiance fluorescent light compared with the wild type, similar to wild type under higher irradiance light during the initial hypocotyl extension phase, and higher during the phase of sustained growth, in which extension involved an increase in the number of cells in the upper region. In all cases, growth of the Ih mutant was more rapid than that of the wild type. It is proposed that CA, and phytochrome control cell elongation primarily through separate mechanisms that interact at a step close to the terminal response.

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Genetic Analysis of the Role of Gibberellin in the Red Light Inhibition of Stem Elongation in Etiolated Seedlings

Cited by 40 publications

References 23 publications

Changes in Gibberellin A1 Levels and Response during De-Etiolation of Pea Seedlings

Changes in Gibberellin A1 Levels and Response during De-Etiolation of Pea Seedlings

Adaptation to Dim-Red Light Leads to a Nongradient Pattern of Stem Elongation in Cucumis Seedlings

Phytochrome, Gibberellins, and Hypocotyl Growth (A Study Using the Cucumber (Cucumis sativus L.) long hypocotyl Mutant)

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