The Dependence of Auxin-Induced Pea Stem Growth on Gibberellin

Ockerse, Ralph

doi:10.1086/336517

Cited by 10 publications

(7 citation statements)

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“…Other phytohormones such as auxin, cytokinin and ethylene had no signi®cant eect on GA 3 -stimulated leaf sheath growth, although IAA reportedly promotes the elongation of pea stem segments in cooperation with GA (Tanimoto et al 1967). Auxin stimulates shoot elongation in pea epicotyls and ethylene enhances the (Ockerse 1970;Yang et al 1996;Raskin and Kende 1984a). The auxin eects on tissue elongation have been widely studied in excised mature tissue rather than the intact and/or immature tissue.…”

Section: Discussionmentioning

confidence: 99%

Promotion of leaf sheath growth by gibberellic acid in a dwarf mutant of rice

Matsukura

Itoh

Nemoto

et al. 1998

Planta

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The mechanism of gibberellin (GA)-induced leaf sheath growth was examined using a dwarf mutant of rice (Oryza sativa L. cv. Tan-ginbozu) treated in advance with an inhibitor of GA biosynthesis. Gibberellic acid (GA 3 ) enhanced the growth of the second leaf sheath, but auxins did not. Measurement of the mitotic index and cell size revealed that cell elongation rather than cell division is promoted by GA 3 . Gibberellic acid increased the extensibility of cell walls in the elongation zone of the leaf sheath. It also increased the total amount of osmotic solutes including sugars in the leaf sheath, but did not increase the osmotic concentration of the cell sap, due to an accompanying increase in cell volume by water absorption. In the later stage of GA 3 -induced growth, starch granules completely disappeared from leaf sheath cells, whereas dense granules remained in control plants. These ®ndings indicate that GA enhances cell elongation by increasing wall extensibility, osmotic concentration being kept unchanged by starch degradation. Materials and methodsPlant materials. Seeds of rice (Oryza sativa L. cv. Tan-ginbozu), a dwarf mutant derived from the cultivar Ginbozu, were a gift from Abbreviations: ABA cis-abscisic acid; 2,4-D 2,4-dichlorophenoxyacetic acid; GA n gibberellin A n ; GA 3 gibberellic acid; PAS Periodic acid-Schi reaction; PCIB p-chlorophenoxy-isobutyric acid; TIBA 2,4,5-triiodobenzoic acid

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Section: Discussionmentioning

confidence: 99%

Promotion of leaf sheath growth by gibberellic acid in a dwarf mutant of rice

Matsukura

Itoh

Nemoto

et al. 1998

Planta

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“…However, with the addition of exogenous IAA, applied GA manifested a specific growth response in these segments beyond the large response inducible by IAA alone; pretreatment with GA further enhanced the growth response of these segments to a subsequent treatment with IAA (Brian and Hemming, 1958;Ockerse and Galston, 1967;Ockerse, 1970;Reid and Davies, 1992). Clearly, these responses also occur in intact plants but are limited to IAA-deficient lkb dwarfs (Fig.…”

Section: Lnteractions Between Auxin and Ga: Responsiveness And Biosynmentioning

confidence: 98%

Genetic Dissection of the Relative Roles of Auxin and Gibberellin in the Regulation of Stem Elongation in Intact Light-Grown Peas

1996

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“…In fact, a comparison between le-1 and LE segments already existed in the literature. Ockerse and Galston (1967) and Ockerse (1970) reported that the growth response to IAA was indeed less in le-1 segments than in LE segments. These workers used the unrelated lines Alaska (LE) and Progress No.…”

Section: Integrating the Old With The Newmentioning

confidence: 99%

“…Barratt and also reported a stronger effect of IAA on segments from a tall, compared with a dwarf (le-3) line, in ''mid-expansion'' segments. Ockerse and Galston (1967) and Ockerse (1970) suggested that as the phenotypic difference between their tall and dwarf lines was most likely due to a difference in GA content, the growth response to auxin is dependent on GA. That is, they suggested that GA present in the tissue enhances the auxin response. Our present results show that the level of bioactive GA in internode segments rapidly drops after excision, and that auxin prevents this from happening.…”

Section: Integrating the Old With The Newmentioning

confidence: 99%

Auxin-Gibberellin Interactions in Pea: Integrating the Old with the New

Ross

O'Neill

Rathbone

2003

J Plant Growth Regul

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Recent findings on auxin-gibberellin interactions in pea are reviewed, and related to those from studies conducted in the 1950s and 1960s. It is now clear that in elongating internodes, auxin maintains the level of the bioactive gibberellin, GA 1 , by promoting GA 1 biosynthesis and by inhibiting GA 1 deactivation. These effects are mediated by changes in expression of key GA biosynthesis and deactivation genes. In particular, auxin promotes the step GA 20 to GA 1 , catalyzed by a GA 3-oxidase encoded by Mendel's LE gene. We have used the traditional system of excised stem segments, in which auxin strongly promotes elongation, to investigate the importance for growth of auxin-induced GA 1 . After excision, the level of GA 1 in wild-type (LE) stem segments rapidly drops, but the auxin indole-3acetic acid (IAA) prevents this decrease. The growth response to IAA was greater in internode segments from LE plants than in segments from the le-1 mutant, in which the step GA 20 to GA 1 is impaired. These results indicate that, at least in excised segments, auxin partly promotes elongation by increasing the content of GA 1 . We also confirm that excised (light-grown) segments require exogenous auxin in order to respond to GA. On the other hand, decapitated internodes typically respond strongly to GA 1 application, despite being auxin-deficient. Finally, unlike the maintenance of GA 1 content by auxin, other known relationships among the growth-promoting hormones auxin, brassinosteroids, and GA do not appear to involve large changes in hormone level.

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The Dependence of Auxin-Induced Pea Stem Growth on Gibberellin

Cited by 10 publications

References 0 publications

Promotion of leaf sheath growth by gibberellic acid in a dwarf mutant of rice

Promotion of leaf sheath growth by gibberellic acid in a dwarf mutant of rice

Genetic Dissection of the Relative Roles of Auxin and Gibberellin in the Regulation of Stem Elongation in Intact Light-Grown Peas

Auxin-Gibberellin Interactions in Pea: Integrating the Old with the New

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