Long‐term Developmental Changes in Xanthium Induced by Gibberellic Acid

Maksymowych, Roman; Cordero, Robert E.; Erickson, Ralph O.

doi:10.1002/j.1537-2197.1976.tb13188.x

Cited by 24 publications

(16 citation statements)

References 13 publications

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“…In rosette plants, cell division is activated before stem elongation, and ·it is related to the action of gibberellins in the apical meristem (Sachs, 1965). Xanth£um treated with GA 3 showed a higher cell division rate, with doubling of AD size (Maksymowych et al, 1976). These results indicate that active cell division increases AD size during the vegetative stage.…”

Section: Discussionmentioning

confidence: 85%

Relationship between Apical Dome Diameter at Panicle Initiation and the Size of Panicle Components in Rice Grown under Different Nitrogen Conditions during the Vegetative Stage

Kobayasi

Horie

Imaki

2002

Plant Production Science

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Section: Discussionmentioning

confidence: 85%

Relationship between Apical Dome Diameter at Panicle Initiation and the Size of Panicle Components in Rice Grown under Different Nitrogen Conditions during the Vegetative Stage

Kobayasi

Horie

Imaki

2002

Plant Production Science

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“…Because the phyllotaxy of pla1 is normal, positional regulation of leaf primordia is not affected, suggesting that in pla1, enlarged SAM is differently organized from that of abphyl. It was reported that exogenous application of a gibberellic acid resulted in the enlargement of SAM via activated cell divisions, and that rapid leaf initiation and phyllotactic change in Xanthium pennsylvanicum (49)(50)(51). Also, the inhibition of auxin transport affects the phyllotaxy and leaf emergence rate in Arabidopsis and tomato (52,53).…”

Section: Discussionmentioning

confidence: 99%

PLASTOCHRON1 , a timekeeper of leaf initiation in rice, encodes cytochrome P450

Miyoshi

Ahn

Kawakatsu

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

172

176

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During postembryonic development of higher plants, the shoot apical meristem produces lateral organs in a regular spacing (phyllotaxy) and a regular timing (plastochron). Molecular analysis of mutants associated with phyllotaxy and plastochron would greatly increase understanding of the developmental mechanism of plant architecture because phyllotaxy and plastochron are fundamental regulators of plant architecture. pla1 of rice is not only a plastochron mutant showing rapid leaf initiation without affecting phyllotaxy, but also a heterochronic mutant showing ectopic shoot formation in the reproductive phase. Thus, pla1 provides a tool for analyzing the molecular basis of temporal regulation in leaf development. In this work, we isolated the PLA1 gene by map-based cloning. The identified PLA1 gene encodes a cytochrome P450, CYP78A11, which potentially catalyzes substances controlling plant development. PLA1 is expressed in developing leaf primordia, bracts of the panicle, and elongating internodes, but not in the shoot apical meristem. The expression pattern and mutant phenotype suggest that the PLA1 gene acting in developing leaf primordia affects the timing of successive leaf initiation and the termination of vegetative growth.

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“…These experiments provided evidence that factors of either a chemical or a physical nature could affect leaf position and the angle between leaves. Not surprisingly, the classical plant hormones, particularly auxin and gibberellin, were implicated, although their specific role in organ initiation and positioning has not been determined (Snow and Snow, 1937;Gorter, 1949Gorter, , 1951Bedesem, 1958;Kiermayer, 1960;Schwabe, 1971;Maksymowych and Maksymowych, 1973;Maksymowych et al, 1976;Maksymowych and Erickson, 1977;Meicenheimer, 1981).…”

Section: Introductionmentioning

confidence: 99%

Auxin Regulates the Initiation and Radial Position of Plant Lateral Organs

2000

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Leaves originate from the shoot apical meristem, a small mound of undifferentiated tissue at the tip of the stem. Leaf formation begins with the selection of a group of founder cells in the so-called peripheral zone at the flank of the meristem, followed by the initiation of local growth and finally morphogenesis of the resulting bulge into a differentiated leaf. Whereas the mechanisms controlling the switch between meristem propagation and leaf initiation are being identified by genetic and molecular analyses, the radial positioning of leaves, known as phyllotaxis, remains poorly understood. Hormones, especially auxin and gibberellin, are known to influence phyllotaxis, but their specific role in the determination of organ position is not clear. We show that inhibition of polar auxin transport blocks leaf formation at the vegetative tomato meristem, resulting in pinlike naked stems with an intact meristem at the tip. Microapplication of the natural auxin indole-3-acetic acid (IAA) to the apex of such pins restores leaf formation. Similarly, exogenous IAA induces flower formation on Arabidopsis pin-formed1-1 inflorescence apices, which are blocked in flower formation because of a mutation in a putative auxin transport protein. Our results show that auxin is required for and sufficient to induce organogenesis both in the vegetative tomato meristem and in the Arabidopsis inflorescence meristem. In this study, organogenesis always strictly coincided with the site of IAA application in the radial dimension, whereas in the apical-basal dimension, organ formation always occurred at a fixed distance from the summit of the meristem. We propose that auxin determines the radial position and the size of lateral organs but not the apical-basal position or the identity of the induced structures. INTRODUCTIONLeaf primordia develop in regular patterns from the shoot apical meristem. In the majority of flowering plants, the leaves are arranged in spirals, with the divergence angle between successive leaves approaching the Fibonacci angle of 137.5 Њ , the so-called golden ratio (Steeves and Sussex, 1989;Lyndon, 1990Lyndon, , 1998Jean, 1994). Molecular and genetic analyses have recently identified various genes that regulate meristem development and leaf formation. Some of these genes encode transcription factors of the homeobox class (Vollbrecht et al., 1991;Long et al., 1996;Kerstetter et al., 1997; Taylor, 1997;Mayer et al., 1998), whereas others, such as clavata1 , clavata3, and zwille, appear to be involved in cell-to-cell signaling Moussian et al., 1998;Fletcher et al., 1999; Trotochaud et al., 1999). Current models postulate that these genes control the balance between meristem self-propagation and the production of organogenic tissue.Whereas genetic analyses provide us with an ever more detailed description of meristem maintenance and propagation, the molecular nature of the mechanisms that trigger leaf initiation and ensure that leaves form at the proper angles relative to each other remains to be established. In many m...

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Long‐term Developmental Changes in Xanthium Induced by Gibberellic Acid

Cited by 24 publications

References 13 publications

Relationship between Apical Dome Diameter at Panicle Initiation and the Size of Panicle Components in Rice Grown under Different Nitrogen Conditions during the Vegetative Stage

Relationship between Apical Dome Diameter at Panicle Initiation and the Size of Panicle Components in Rice Grown under Different Nitrogen Conditions during the Vegetative Stage

PLASTOCHRON1 , a timekeeper of leaf initiation in rice, encodes cytochrome P450

Auxin Regulates the Initiation and Radial Position of Plant Lateral Organs

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