Auxin controls local cytokinin biosynthesis in the nodal stem in apical dominance

Tanaka, Mina; Takei, Kentaro; Kojima, Mikiko; Sakakibara, Hitoshi; Mori, Hitoshi

doi:10.1111/j.1365-313x.2006.02656.x

Cited by 434 publications

(391 citation statements)

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“…While likely a trigger for bud release, cytokinin may also promote auxin production and basipetal auxin transport out of growing buds, which consequently represses the production of cytokinin lower in the stem and limits its availability for other buds (Bangerth et al, 2000;Tanaka et al, 2006;Shimizu-Sato et al, 2009).…”

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

et al. 2009

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Section: Introductionmentioning

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“…Although an antagonistic role of auxin and cytokinin in the regulation of apical dominance has been postulated for decades, little is known about the underlying molecular mechanisms. Recent studies have shown that auxin can regulate the expressions of IPT genes and that cytokinin biosynthesis is directly affected by auxin in local shoots [32,33], suggesting that auxin may modulate cytokinin concentration and thus represses AM outgrowth [31,[34][35][36].Recent studies on a series of branching mutants, such as more axillary growth (max) of Arabidopsis [37][38][39][40], ramosus (rms) mutants of pea [41][42][43], decreased apical dominance (dad) mutants of petunia [44,45] and dwarf (d) mutants of rice [46][47][48][49][50][51], have revealed strigolactone as a second messenger of auxin action on the control of AM outgrowth [52,53]. Strigolactones, a group of terpenoid lactones that have been found in root exudates of diverse plant species, are synthesized from carotenoids in roots and transported acropetally or synthesized locally to repress the outgrowth of shoot branches [38,[54][55][56].…”

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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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“…Auxin, derived from the shoot apex and moving basipetally, inhibits growth of axillary buds, while cytokinin, thought to be derived from the roots, promotes their growth (Cline, 1994;Leyser, 2003). Tanaka et al (2006) indicated that one role of auxin is to repress local biosynthesis of cytokinins in the nodal stem and that, after decapitation, cytokinins are locally biosynthesized in the nodal stem rather than in the roots. The reduced main shoot elongation during winter (December) probably restricted apical dominance and thus more axillary buds were developed at this period (Table 3), resembling the species behaviour in the wild, where new vegetation sprouts in winter.…”

Section: Establishment Of Rooted Cuttingsmentioning

confidence: 99%

Rooting and establishment of Limoniastrum monopetalum (L.) Boiss stem-tip cuttings

Akoumianaki‐Ioannidou¹,

Martini²,

Papafotiou³

2016

Afr. J. Plant Sci.

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Rooting of Limoniastrum monopetalum stem-tip cuttings and establishment of produced plantlets were investigated in order to facilitate the use of the species in urban and suburban areas, and historical Mediterranean landscapes as an ornamental plant. Cuttings collected in winter or spring rooted at higher percentages than those collected in summer or autumn. Water-ethanol solutions containing 1000 to 3000 mg L -1 indol-3-butyric acid (IBA) were more effective in rooting induction than the controls that did not contain IBA or powder IBA for softwood cuttings. Dipping for 1 min in an IBA solution was more effective than dipping for 5 min. Ethanol used in the IBA-solutions inhibited rooting depending on dipping time. All plantlets survived after transplantation. Plantlets transplanted on a peat-perlite (2 : 1, v/v) mixture and fertilized once a month, with 2 or 4 g L -1 water-soluble complete fertilizer, had bigger elongation and produced more axillary shoots than those transplanted on a mixture amended with grape marc compost or enriched peat. Pinching of the main shoot one month after transplantation promoted axillary shoots production and a more compact plant shape.

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Auxin controls local cytokinin biosynthesis in the nodal stem in apical dominance

Cited by 434 publications

References 56 publications

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

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

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

Rooting and establishment of Limoniastrum monopetalum (L.) Boiss stem-tip cuttings

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