Analysis of Cycles of Dormancy and Growth in Pea Axillary Buds Based on mRNA Accumulation Patterns of Cell Cycle-Related Genes

Shimizu, Sota; Mori, Hitoshi

doi:10.1093/oxfordjournals.pcp.a029365

Cited by 72 publications

(53 citation statements)

References 28 publications

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“…To investigate whether the loss of apical dominance of bud2 plants involves auxin action, we examined the hypocotyl elongation at higher temperature and the lateral shoot development after decapitation of wild-type and bud2 mutant plants [43,57,58]. Identification of temperatureinduced hypocotyl elongation is a simple and rapid assay in the study of an auxin-mediated growth response [59].…”

Section: The Bud2 Plant Shows Altered Hypocotyl Elongation and Lateramentioning

confidence: 99%

The BUD2 mutation affects plant architecture through altering cytokinin and auxin responses in Arabidopsis

et al. 2010

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The ratio of auxin and cytokinin plays a crucial role in regulating aerial architecture by promoting or repressing axillary bud outgrowth. We have previously identified an Arabidopsis mutant bud2 that displays altered root and shoot architecture, which results from the loss-of-function of S-adenosylmethionine decarboxylase 4 (SAMDC4). In this study, we demonstrate that BUD2 could be induced by auxin, and the induction is dependent on auxin signaling. The mutation of BUD2 results in hyposensitivity to auxin and hypersensitivity to cytokinin, which is confirmed by callus induction assays. Our study suggests that polyamines may play their roles in regulating the plant architecture through affecting the homeostasis of cytokinins and sensitivities to auxin and cytokinin. IntroductionPolyamines, including diamine putrescine, triamine spermidine and tetraamine spermine, are low-molecularmass organic cations. They exist widely in all living organisms and are essential for their survival, because blocking of the biosynthesis of polyamines leads to lethal phenotypes in animals [1] and higher plants [2][3][4]. In higher plants, polyamines have been proposed to function in response to environmental stresses and in regulating growth and development [4][5][6][7][8][9][10][11]. Plant molecular and physiological studies over past decades have shown that higher plants defective in producing polyamines often have altered plant architecture, with reduced plant height or more branches in shoots and roots [4,[10][11][12][13]. However, the underlying mechanisms still remain largely elusive.Branches of higher plants originate from the axillary meristems (AMs) of shoots, and formation of a branch generally consists of the initiation of a new AM and its subsequent outgrowth. However, an AM may arrest its growth under some conditions, forming a dormant bud. The dormant buds will release their outgrowth once they sense a permissible environmental or developmental signal. In many plant species, axillary buds become dormant due to the inhibiting effects of the primary shoot apex on the outgrowth of AMs, a phenomenon known as 'apical dominance'. Auxin was first regarded as a direct regulator in this process [14], a notion strengthened thereafter by physiological studies on decapitated shoot apices [15][16][17], and by analyzing auxin biosynthesis, transport and signaling [18][19][20][21][22][23][24][25][26][27][28][29] in plants. However, when radiolabelled auxin was applied to a decapitated stump, the outgrowth of axillary buds was inhibited even though radiolabelled auxin was not found to accumulate in axillary buds, suggesting an indirect suppression effect of auxin on the AM outgrowth [28,30] and the presence of second messengers.Cytokinin has been proposed as a second messenger that mediates the action of auxin in controlling the apical dominance, because it promotes the outgrowth of lateral buds when directly applied to buds [31]. Although an antagonistic role of auxin and cytokinin in the regulation of apical dominance has been postu...

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Section: The Bud2 Plant Shows Altered Hypocotyl Elongation and Lateramentioning

confidence: 99%

The BUD2 mutation affects plant architecture through altering cytokinin and auxin responses in Arabidopsis

et al. 2010

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“…These dormant axillary buds resume development at a later time depending on their developmental program or in response to environmental cues. The cycles between dormancy and growth in axillary buds were characterized using the garden pea (Stafstrom and Sussex, 1992;Devitt and Stafstrom, 1995;Shimizu and Mori, 1998a). The second node of pea plants has four dormant axillary buds, and all of the axillary buds are different sizes.…”

Section: Development and Potential Of Axillary Meristemsmentioning

confidence: 99%

“…Analyses of the mitotic index indicated that removal of the terminal bud rapidly promotes cell division in axillary buds (Martin, 1987). In pea axillary buds, the proliferating and quiescent (phase of the cell cycle in which the dormant bud cells are arrested) cell cycles are characterized by mRNA accumulation patterns of several cell cycle-related genes (Devitt and Stafstrom, 1995;Shimizu and Mori, 1998a). These gene transcripts accumulate in a cell cycle-specific fashion.…”

Section: Molecular Approachmentioning

confidence: 99%

Control of Outgrowth and Dormancy in Axillary Buds

2001

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The shoot system has an important role in generating a large variety of diverse plant forms (Steeves and Sussex, 1989). The overall architecture of the shoot system is derived from the activity of the primary shoot apical meristem (SAM), arising during embryogenesis, together with the activity of the additional meristems subsequently formed after seed germination. The primary SAM provides the main axis of the plant body. Plant architecture is further modified by shoot branching that results from the activity of the additional meristems. The complexity of the branching pattern depends on the temporal and spatial development of these branches. These characteristics, although they are plastic in their response to environmental cues, are genetically determined. The developmental program that specifies branching patterns in different plant species is fundamentally important for generating species-specific plant forms.The shoot branching process generally involves two developmental stages: the formation of axillary meristems in the leaf axils and the growth of axillary buds. In many plant species, the growth of axillary meristems is inhibited by the primary shoot or primary inflorescence. This phenomenon is generally known as apical dominance. The plant hormones auxin and cytokinin are thought to have a major role in controlling this process (Phillips, 1975;Cline, 1994;Tamas, 1995;Napoli et al., 1999). Auxin has an inhibitory effect on the growth of axillary buds, whereas cytokinin promotes axillary bud outgrowth. The mechanisms of axillary bud outgrowth depend on the ratio of these two hormones rather than the absolute levels of either hormone.A variety of experimental approaches have been used to examine the mechanisms controlling dormancy and outgrowth of axillary buds. These range from physiological studies, such as measurement and exogenous application of plant hormones, to analyses of transgenic plants overexpressing hormone biosynthetic genes to alter endogenous hormone levels. Isolation and characterization of mutations that cause alterations in shoot branching patterns are powerful approaches. These molecular genetic approaches combined with the conventional physiological studies, such as grafting experiments, revealed that not only do auxin and cytokinin function to control the growth of axillary buds, but other factors and/or signals also have important roles. More recently, the genes expressed in dormant axillary buds were isolated and characterized.This review focuses on recent findings uncovered by physiological, genetic, and molecular studies and approaches to investigate the control of shoot branching, apical dominance, and dormancy in plants. DEVELOPMENT AND POTENTIAL OF AXILLARY MERISTEMS

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“…Indeed, dormant buds are highly developed and would presumably require vascular connections for early development and growth before they enter a stage of dormancy. Additionally, buds could become active and later reenter a stage of dormancy (Stafstrom and Sussex, 1992;Shimizu and Mori, 1998). In contrast to these findings, Sorokin and Thimann (1964) reported that xylem strands from an axillary bud did not connect with those from the main stem until after release from apical dominance.…”

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confidence: 93%

Strigolactone Acts Downstream of Auxin to Regulate Bud Outgrowth in Pea and Arabidopsis

et al. 2009

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During the last century, two key hypotheses have been proposed to explain apical dominance in plants: auxin promotes the production of a second messenger that moves up into buds to repress their outgrowth, and auxin saturation in the stem inhibits auxin transport from buds, thereby inhibiting bud outgrowth. The recent discovery of strigolactone as the novel shootbranching inhibitor allowed us to test its mode of action in relation to these hypotheses. We found that exogenously applied strigolactone inhibited bud outgrowth in pea (Pisum sativum) even when auxin was depleted after decapitation. We also found that strigolactone application reduced branching in Arabidopsis (Arabidopsis thaliana) auxin response mutants, suggesting that auxin may act through strigolactones to facilitate apical dominance. Moreover, strigolactone application to tiny buds of mutant or decapitated pea plants rapidly stopped outgrowth, in contrast to applying N-1-naphthylphthalamic acid (NPA), an auxin transport inhibitor, which significantly slowed growth only after several days. Whereas strigolactone or NPA applied to growing buds reduced bud length, only NPA blocked auxin transport in the bud. Wild-type and strigolactone biosynthesis mutant pea and Arabidopsis shoots were capable of instantly transporting additional amounts of auxin in excess of endogenous levels, contrary to predictions of auxin transport models. These data suggest that strigolactone does not act primarily by affecting auxin transport from buds. Rather, the primary repressor of bud outgrowth appears to be the auxindependent production of strigolactones.

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Analysis of Cycles of Dormancy and Growth in Pea Axillary Buds Based on mRNA Accumulation Patterns of Cell Cycle-Related Genes

Cited by 72 publications

References 28 publications

The BUD2 mutation affects plant architecture through altering cytokinin and auxin responses in Arabidopsis

The BUD2 mutation affects plant architecture through altering cytokinin and auxin responses in Arabidopsis

Control of Outgrowth and Dormancy in Axillary Buds

Strigolactone Acts Downstream of Auxin to Regulate Bud Outgrowth in Pea and Arabidopsis

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