Auxins

Moore, Thomas C.

doi:10.1007/978-1-4612-3654-2_2

Cited by 3 publications

(3 citation statements)

References 151 publications

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“…Two synthetic auxins were used: 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) (Moore, 1989). The results obtained with these auxins were almost identical and therefore only the effects on embryo development induced by 2,4,5 T are described in detail.…”

Section: Effect Of Exogenous Auxins On the In Vitro Development Of Whmentioning

confidence: 99%

“…The effect on embryo development of the two synthetic auxins used, 2,4,5-T and 2,4-D, has been compared with the effect of the natural auxin: indole-3-acetic acid (IAA; Moore, 1989). When IAA was added to the culture medium of globular proembryos at 10-50 pM, a similar radial growth pheno- cr, coleoptilar ring; Ip, first leaf primordium; rm, root apical meristem; sc, scutellum; sm, shoot apical meristem; sp, suspensor; zcd, zone of cell division; zce, zone of cell elongation.…”

Section: Effect Of Exogenous Auxins On the In Vitro Development Of Whmentioning

confidence: 99%

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Influence of auxin on the establishment of bilateral symmetry in monocots

Fischer

Neuhaus²

1996

The Plant Journal

104

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SummaryTo study the influence of auxin on the shift from radial to bilateral symmetry during monocot embryogenesis, the fate of young wheat (Triticurn aestivum L.) zygotic embryos has been manipulated in vitro by adding auxins, an auxin transport inhibitor and an auxin antagonist to the culture medium. The two synthetic auxins used, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), induced identical phenotypes. In the most severe cases, the shift from radial to bilateral symmetry was blocked resulting in continuous uniform radial growth. The natural auxin indole-3-acetic acid (IAA) induced the same phenotype. The effect of 2,4,5-T and 2,4-D depended on their concentrations and on the developmental stage of the isolated embryos. In the presence of 2,3,5-triiodobenzoic acid (TIBA), an auxin transport inhibitor, the overall embryo symmetry was abnormal. The relative position of the shoot apical meristem in comparison with the scutellum was anomalous. The quality of shoot apical meristem and the scutellum differentiation was altered compared with normal developed embryos. No root meristem was differentiated. The effect of TIBA depends on its concentration and on the developmental stage of the isolated embryos. By contrast, 2-(pchlorophenoxy)-2-methylpropionic acid (PCIB) which is described as an auxin antagonist, has no visible direct effect on the embryonic symmetry. These observations indicate that auxin influences the change from radial symmetry to embryonic polarity during monocot embryogenesis. A model of auxin action during early wheat embryo development is proposed.

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Section: Effect Of Exogenous Auxins On the In Vitro Development Of Whmentioning

confidence: 99%

Section: Effect Of Exogenous Auxins On the In Vitro Development Of Whmentioning

confidence: 99%

Influence of auxin on the establishment of bilateral symmetry in monocots

Fischer

Neuhaus²

1996

The Plant Journal

104

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“…Auxins apparently function in the same way in tomato as they do in many other plants: they promote root growth, maintain apical dominance, and regulate phototropic and gravitropic behavior (Moore, 1989). The role of auxins in tomato development has been investigated using the dgt mutant (Daniel et al, 1989).…”

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confidence: 99%

NaCI Reduces Indole-3-Acetic Acid Levels in the Roots of Tomato Plants Independent of Stress-Induced Abscisic Acid

Dunlap¹,

Binzel²

1996

Plant Physiology

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Indole-3-acetic acid (IAA) was measured in leaves and roots of tomato (Lycopersicon esculentum) genotypes subjected to salt stress. An abscisic acid (ABA)-deficient mutant of tomato (sitiens), the genetic parent (Rheinlands Ruhm, RR), and a commercial variety (Large Cherry Red, LCR) of tomato were treated with 50 to 300 mM NaCl in nutrient culture. Both LCR and RR had significantly higher levels of IAA in the roots compared with that in sitiens prior to treatment. The initial levels of IAA in the roots of LCR and RR declined by nearly 75% after exposure to NaCl, whereas those in roots from the sitiens mutant remained unchanged. IAA levels in the leaves of all genotypes remained unchanged or increased slightly in response to NaCl. ABA was highest in leaves from the normal genotypes after exposure to NaCl. ABA levels in the roots of sitiens were similar to the levels in the normal genotypes, whereas levels in the leaves were only 10% of the levels found in normal genotypes regardless of the salt treatment. Treatment of LCR and sitiens with exogenous ABA increased the ABA levels in leaves and roots, but there were no measurable changes in endogenous IAA. Therefore, the reduction in IAA appears to result from an ABA-independent effect of NaCl on IAA metabolism in the roots of stressed plants.

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Red light causes a reduction in IAA levels at the apical tip by inhibiting de novo biosynthesis from tryptophan in maize coleoptiles

Nishimura

Mori

Furukawa

et al. 2006

Planta

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When maize coleoptiles were unilaterally exposed to red light (7.9 micromol m(-2)s(-1) for 5 min), 3 h after treatment IAA levels in coleoptiles decreased in all regions, from top to basal, with levels about 60% of dark controls. Localized irradiation in the 5 mm top zone was sufficient to cause the same extent of IAA reduction in the tips to that in the tips of whole irradiated shoots. When coleoptiles were treated with N-1-naphthylphthalamic acid (NPA), an accumulation of IAA in the tip and a decrease of diffusible IAA from tips were simultaneously detected. IAA accumulation in red-light treated coleoptiles by NPA was much lower than that of dark controls. NPA treatment did not affect the content of conjugated IAA in either dark or light treated coleoptile tips. When (13)C(11) (15)N(2)-tryptophan (Trp) was applied to the top of coleoptiles, substantial amounts of stable isotope were incorporated into free IAA in dark and red-light treated coleoptile tips. The ratio of incorporation was slightly lower in red-light treated coleoptile tips than that in dark controls. The label could not be detected in conjugated IAA. The rate of basipetal transport of IAA was about 10 mm h(-1) and the velocity was not affected by red light. These results strongly suggest that red light does not affect the rates of conversion of free IAA to the conjugate form or of the basipetal transport, but just reduces the IAA level in the tips, probably inhibited by IAA biosynthesis from Trp in this region.

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Auxins

Cited by 3 publications

References 151 publications

Influence of auxin on the establishment of bilateral symmetry in monocots

Influence of auxin on the establishment of bilateral symmetry in monocots

NaCI Reduces Indole-3-Acetic Acid Levels in the Roots of Tomato Plants Independent of Stress-Induced Abscisic Acid

Red light causes a reduction in IAA levels at the apical tip by inhibiting de novo biosynthesis from tryptophan in maize coleoptiles

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