Auxin and Cytokinins in the Control of Apical Dominance in Pea — A Differential Response Due to Bud Position

Blažková, Jarmila; Krekule, J.; Macháčková, Ivana; Procházka, Stanislav

doi:10.1016/s0176-1617(99)80246-6

Cited by 14 publications

(8 citation statements)

References 17 publications

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“…The con ven tional view of a di rectly in hib i tory role of IAA in bud out growth is sup ported by Blazkova et al (1999), how ever, this view has been con tradicted by Gocal et al (1991) and Pearce et al (1995) who re port on a rise of IAA lev els in buds cor re lated with bud growth. Fur ther, it has been sug gested (Mac don ald 1997), that IAA prob a bly af fects dor mancy by re act ing with auxin bind ing pro teins, how ever, the func tional role of pro tein recep tors in auxin sig nal ing (Abel and Theologis 1996) is un clear along with the mo lec u lar mech anism of auxin ac tion in dor mancy.…”

Section: Re Sults and Discussionmentioning

confidence: 99%

Changes in endogenous auxins during winter dormancy in tea (Camellia sinensis L.) O. Kuntze

Nagar

Sood

2006

Acta Physiol Plant

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Ab stractChanges in en dog e nous auxin (IAA) were de ter mined in tea shoots with the on set of win ter dor mancy (30 Oc to ber) and sub se quent to dor mancy re lease (15 April). Very low lev els of free IAA were de tected in dor mant shoots when they were still in deep dor mancy. The lev els in creased af ter 30 Jan u ary and reached high est value af ter dor mancy re lease. Con ju gated IAA lev els in creased with on set of dor mancy reach ing its max i mum value when free IAA lev els were low est. With in crease in free IAA lev els, the con ju gated IAA lev els de creased in shoots prior to dor mancy re lease sug gest ing of met a bolic interconversion of IAA dur ing these pe ri ods. The pos si ble roles of free and con ju gated IAA in dor mancy and fol low ing its re lease are dis cussed in re la tion to win ter dor mancy in tea shoots.List of ab bre vi a tions: IAA, indole-3-ace tic acid; BHT, butylated hydroxytoluene; ABA, Abscisic acid; PVP, polyvinylpyrrolidone In tro duc tionThe phe nom e non of dor mancy or de vel op men tal ar rest is an im por tant adap tive mech a nism that bene fits sur vival of a spe cies un der un fa vor able con ditions (Juntilla 1988). It is con sid ered as a phase in the plants life cy cle dur ing which the usual processes con trib ut ing to or derly growth and de vel opment are re stricted. Seeds and veg e ta tive propagules like corms, tu bers, bulbs and rhi zomes etc. of most plant spe cies even un der highly fa vor able con di tions do not ger mi nate/ sprout soon af ter matu rity. This pe riod of sus pended growth has been de fined as in nate dor mancy (Wareing 1977) while in the case of im posed dor mancy the growth is suspended be fore the on set of ad verse cli ma tic con ditions. Be cause of its ba sic and ap plied na ture the mech a nism of dor mancy has at tracted con sid er able in ter est (Lang 1996). In api cal buds of grape vines , peach (Faye and Floch 1999) and tu ber ous or gans (Suttle 1996) dor mancy has been well char ac ter ized.Tea plants grow ing be yond 16 o N or S lat i tudes face win ter dor mancy with cor re spond ing vari ations in day and night tem per a tures (Barua 1989). The state of growth in tea is de ter mined with the start of win ter dor mancy and its sub se quent releases. Barua (1969) in duced dor mant tea buds to grow by in ject ing GA 3 and sug gested that the balance of growth pro mot ing and in hib it ing substances might de ter mine the state of dor mancy in tea shoots. High lev els of free abscisic acid (ABA) and phe nols were ob served in dor mant shoots of tea and it was sug gested that they could pos si bly play 165

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Section: Re Sults and Discussionmentioning

confidence: 99%

Changes in endogenous auxins during winter dormancy in tea (Camellia sinensis L.) O. Kuntze

Nagar

Sood

2006

Acta Physiol Plant

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“…By strengthening of the elongation growth of the epicotyl they also amplify the apical dominance of the stem. On the other hand cytokinins attenuate the apical dominance (Blažková et al 1999) and these results in an initiation of branching of the stem and in an inhibition of its elongation growth. This effect can be induced by cytokinins biosynthesised both in roots (Šebánek et al 1991) and leaves (Miyawaki et al 2004).…”

Section: Discussionmentioning

confidence: 99%

“…The recent literary data concerning growth correlations in pea seedlings paid attention above all to the phytohormonal principles of the apical dominance over lateral buds (Blažková et al 1999, Procházka and Truksa 1999, Li and Bangerth 2003. However, growth correlations existing between roots and stem are not practically mentioned.…”

mentioning

confidence: 99%

Role of cytokinins in growth correlations between roots and stems in pea (Pisum sativum L.) seedlings

Fišerová¹,

Šebánek²,

Hradilík³

et al. 2006

PLANT SOIL ENVIRON

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Pea seeds were swollen in solutions with different concentrations of cytokinin benzyladenine (BA). As compared with controls, a low concentration of BA (0.05 mg/l) did not affect the growth of stems and roots of twelve-day-old seedlings but concentrations of 0.20-4.00 mg/l showed an inhibiting effect; this inhibition was proportional to the concentration of BA. In controls the ratio between the lengths of stems and roots was equal to 1.14, while in seedlings influenced by BA in concentration of 0.20 mg/l its value was significantly lowered to 0.91. Also in six-day-old pea seedlings cultivated under in vitro conditions, BA concentrations of 0.70 and 3.30 mg/l inhibited the growth of roots and epicotyls and significantly increased the production of ethylene (by 150 and 330%, respectively). Three hours after the amputation of the root of five-day-old pea seedlings the level of cytokinin trans-zeatin increased in the apical part of the stem. Within the interval of 48 hours after the amputation of the root the concentration of this plant hormone gradually decreased again. The initial increase in the zeatin level in the stem indicates that the absence of the root induces a reduction of growth-inhibiting effects of roots, which negatively influences the zeatin level in the stem apex at the beginning of germination.

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“…Work on the rms mutants (Beveridge, 2000) and grafts between wild-type and cytokinin-overproducing tobacco (Faiss et al, 1997) suggest that the level of root-derived cytokinin is not a controlling factor in the regulation of branching, as had been proposed previously (Bangerth, 1994;Li et al, 1995;Blazkova et al, 1999). However, more recent studies have suggested that cytokinin synthesized locally in the node may play a role in the regulation of branching.…”

Section: Relationship Between Auxin and Cytokinin In The Regulation Omentioning

confidence: 91%

Auxin Acts in Xylem-Associated or Medullary Cells to Mediate Apical Dominance

2003

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A role for auxin in the regulation of shoot branching was described originally in the Thimann and Skoog model, which proposes that apically derived auxin is transported basipetally directly into the axillary buds, where it inhibits their growth. Subsequent observations in several species have shown that auxin does not enter axillary buds directly. We have found similar results in Arabidopsis. Grafting studies indicated that auxin acts in the aerial tissue; hence, the principal site of auxin action is the shoot. To delineate the site of auxin action, the wild-type AXR1 coding sequence, which is required for normal auxin sensitivity, was expressed under the control of several tissue-specific promoters in the auxin-resistant, highly branched axr1-12 mutant background. AXR1 expression in the xylem and interfascicular schlerenchyma was found to restore the mutant branching to wild-type levels in both intact plants and isolated nodes, whereas expression in the phloem did not. Therefore, apically derived auxin can suppress branching by acting in the xylem and interfascicular schlerenchyma, or in a subset of these cells.

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Auxin and Cytokinins in the Control of Apical Dominance in Pea — A Differential Response Due to Bud Position

Cited by 14 publications

References 17 publications

Changes in endogenous auxins during winter dormancy in tea (Camellia sinensis L.) O. Kuntze

Changes in endogenous auxins during winter dormancy in tea (Camellia sinensis L.) O. Kuntze

Role of cytokinins in growth correlations between roots and stems in pea (Pisum sativum L.) seedlings

Auxin Acts in Xylem-Associated or Medullary Cells to Mediate Apical Dominance

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