Expression of a Gibberellin 2-Oxidase Gene around the Shoot Apex Is Related to Phase Transition in Rice

Sakamoto, Tomoaki; Kobayashi, Masatomo; Itoh, Hironori; Tagiri, Akemi; Kayano, Toshiaki; Tanaka, Hiroshi; Iwahori, Shuichi; Matsuoka, Makoto

doi:10.1104/pp.125.3.1508

Cited by 278 publications

(225 citation statements)

References 35 publications

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“…Similar GA 3 induction was also observed for the Arabidopsis GA2ox genes [16]. However, the rice OsGA2ox1 gene does not respond to exogenous GA 3 [32], suggesting that rice GA catabolism genes might differentially respond to this GA molecule. Detailed analysis of the structures and cis-elements of their promoters would provide further information about their regulation in GA responses.…”

Section: Discussionsupporting

confidence: 51%

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Gibberellin homeostasis and plant height control by EUI and a role for gibberellin in root gravity responses in rice

et al. 2008

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The rice Eui (ELONGATED UPPERMOST INTERNODE) gene encodes a cytochrome P450 monooxygenase that deactivates bioactive gibberellins (GAs). In this study, we investigated controlled expression of the Eui gene and its role in plant development. We found that Eui was differentially induced by exogenous GAs and that the Eui promoter had the highest activity in the vascular bundles. The eui mutant was defective in starch granule development in root caps and Eui overexpression enhanced starch granule generation and gravity responses, revealing a role for GA in root starch granule development and gravity responses. Experiments using embryoless half-seeds revealed that RAmy1A and GAmyb were highly upregulated in eui aleurone cells in the absence of exogenous GA. In addition, the GA biosynthesis genes GA3ox1 and GA20ox2 were downregulated and GA2ox1 was upregulated in eui seedlings. These results indicate that EUI is involved in GA homeostasis, not only in the internodes at the heading stage, but also in the seedling stage, roots and seeds. Disturbing GA homeostasis affected the expression of the GA signaling genes GID1 (GIBBERELLIN INSENSITIVE DWARF 1), GID2 and SLR1. Transgenic RNA interference of the Eui gene effectively increased plant height and improved heading performance. By contrast, the ectopic expression of Eui under the promoters of the rice GA biosynthesis genes GA3ox2 and GA20ox2 significantly reduced plant height. These results demonstrate that a slight increase in Eui expression could dramatically change rice morphology, indicating the practical application of the Eui gene in rice molecular breeding for a high yield potential.

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Section: Discussionsupporting

confidence: 51%

“…Interestingly, strong Eui-GUS expression was observed in vascular bundles (Figure 2). A similar cell-specific pattern was also observed for OsGA2ox1 [32]. It is well established that GAs are produced in certain tissues, particularly in young panicles in rice [33].…”

Section: Discussionsupporting

confidence: 50%

Gibberellin homeostasis and plant height control by EUI and a role for gibberellin in root gravity responses in rice

et al. 2008

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“…It differs from the Green Revolution wheat Rht-B1/Rht-D1, in which the GA signaling pathway is impaired (Sasaki et al, 2002;Spielmeyer et al, 2002;Oikawa et al, 2004). Loss-of-function mutations in the GA20ox and GA3ox genes or overexpression of the gene GA2ox have a dwarfing effect (Sakamoto et al, 2001). In contrast, the slender rice (slr1) plant was found to be a constitutive GAresponsive mutant that was much taller at the seedling stage than the wild-type plant (Ikeda et al, 2001).…”

Section: Control Of Plant Height In Ricementioning

confidence: 89%

Genetic modification of plant architecture and variety improvement in rice

2008

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104

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The structure of the aerial part of a plant, referred to as plant architecture, is subject to strict genetic control, and grain production in cereal crops is governed by an array of agronomic traits. Rice is one of the most important cereal crops and is also a model plant for molecular biological research. Recently, significant progress has been made in isolating and collecting rice mutants that exhibit altered plant architecture. In this article we summarize the recent progress in understanding the basic patterning mechanisms involved in the regulation of tillering (branching) pattern, stem structure and leaf arrangement in rice plants. We discuss the relationship between the genetic modification of plant architecture and the improvement of pivotal agronomic traits in rice.

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“…However, when GA 20 was applied to the leaf of vegetative plants, it had little or no floral activity compared with GA 5 (Evans et al, 1990). Furthermore, the recent report of Sakamoto et al (2001) of high levels of expression of a GA 2-oxidase gene in procambium at the base of the vegetative shoot apex of rice (Oryza sativa), but not in florally evoked apices, suggests that prior to floral evocation there will be rapid catabolism of any GA 20 arriving at the shoot apex. Given such uncertainties, GA 5 is either a primary LD floral stimulus in L. temulentum or its content increases directly at the shoot apex in response to a transported stimulus.…”

Section: Gas Associated With Floral Evocationmentioning

confidence: 99%

“…By contrast, despite the increase in the shoot apex content of GA 5 after a single LD, its content in the apex declining with exposure to multiple LD. Why the spectrum of GAs at the apex shifts over time is a matter for speculation but, for GA 1 and GA 4 which are readily 2␤-hydroxylated, a reduced expression of GA 2-oxidase activity at inflorescence differentiation, as reported in rice (Sakamoto et al, 2001), would allow an increase in apical GA 1 and GA 4 at this time. In a converse manner, in the vegetative shoot apex and at floral evocation these GAs would be degraded but there could be a buildup of GA 5 because of its lesser susceptibility to 2-oxidase activity due to its ring A C2-3 double bond.…”

Section: Gas Associated With Inflorescence Developmentmentioning

confidence: 99%

Long-Day Induction of Flowering in Lolium temulentumInvolves Sequential Increases in Specific Gibberellins at the Shoot Apex

et al. 2001

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One challenge for plant biology has been to identify floral stimuli at the shoot apex. Using sensitive and specific gas chromatography-mass spectrometry techniques, we have followed changes in gibberellins (GAs) at the shoot apex during long day (LD)-regulated induction of flowering in the grass Lolium temulentum. Two separate roles of GAs in flowering are indicated. First, within 8 h of an inductive LD, i.e. at the time of floral evocation, the GA 5 content of the shoot apex doubled to about 120 ng g Ϫ1 dry weight. The concentration of applied GA 5 required for floral induction of excised apices (R.W. King, C. Blundell, L.T. Evans [1993] Aust J Plant Physiol 20: 337-348) was similar to that in the shoot apex. Leaf-applied [ 2 H 4 ] GA 5 was transported intact from the leaf to the shoot apex, flowering being proportional to the amount of GA 5 imported. Thus, GA 5 could be part of the LD stimulus for floral evocation of L. temulentum or, alternatively, its increase at the shoot apex could follow import of a primary floral stimulus. Later, during inflorescence differentiation and especially after exposure to additional LD, a second GA action was apparent. The content of GA 1 and GA 4 in the apex increased greatly, whereas GA 5 decreased by up to 75%. GA 4 applied during inflorescence differentiation strongly promoted flowering and stem elongation, whereas it was ineffective for earlier floral evocation although it caused stem growth at all times of application. Thus, we conclude that GA 1 and GA 4 are secondary, late-acting LD stimuli for inflorescence differentiation in L. temulentum.Plants of Lolium temulentum remain vegetative when grown in short days (SD), but flower after exposure of their leaves to a single long day (LD). The leaf gibberellin (GA) content increases in LD (Gocal et al., 1999) and applied GAs can cause flowering in noninductive SD (Evans, 1964;Pharis et al., 1987;Evans et al., 1990). Thus, GAs mimic LD responses and they could be a transmissible endogenous floral stimulus in this LD plant. A number of other LD plants but not all (for summary, see Metzger, 1995) flower in response to GA, and recent genetic and molecular studies with Arabidopsis support such a role for endogenous GAs in flowering in LD (Wilson et al., 1992;Weigel and Nilsson, 1995;Blásquez et al., 1997). Furthermore, where there are effects of LD exposure on stem elongation there are clear increases in the GA content of leaves, petioles, and shoot tips (Talon and Zeevaart, 1990;Talon et al., 1991;Zeevaart et al., 1993).Inflorescence initiation in L. temulentum after one LD precedes any acceleration of stem elongation. Therefore, if GAs were to play a role endogenously in floral evocation, they should have little effect on stem elongation. From application studies, we previously identified a number of GAs, including GA 5 , that meet this criterion of inducing flowering but with little or no effect on stem elongation (Evans et al., 1990(Evans et al., , 1994a(Evans et al., , 1994b. However, in a broad context, three lines of evi...

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Expression of a Gibberellin 2-Oxidase Gene around the Shoot Apex Is Related to Phase Transition in Rice

Cited by 278 publications

References 35 publications

Gibberellin homeostasis and plant height control by EUI and a role for gibberellin in root gravity responses in rice

Gibberellin homeostasis and plant height control by EUI and a role for gibberellin in root gravity responses in rice

Genetic modification of plant architecture and variety improvement in rice

Long-Day Induction of Flowering in Lolium temulentumInvolves Sequential Increases in Specific Gibberellins at the Shoot Apex

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