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Auxin formation

Auxin Formation. Oxidation or transamination leads to the formation of indolepyruvic acid. Decarboxylation of the keto acid is presumed to result in the formation of indoleacetaldehyde, which can be oxidized by an aldehyde oxidase to indoleacetic acid (V). This compound is excreted by humans, but appears to be the natural auxin, a plant growth hormone. Degradation of auxin by plants appears to involve a peroxidase acting as an oxidase. Horseradish peroxidase plus Mn++ carry out the same... [Pg.350]

Next to the amount of P, the chemical form of this nutrient (Lambers et al. 2002 Shu et al. 2005 Shane et al. 2008) and the availability of other nutrients, especially nitrogen, potassium, and iron (Shane and Lambers 2005) affects the formation of cluster roots. It seems to be regulated by several plant hormones. Thus, application of auxin led to the production of cluster roots in white lupin at P concentrations that normally suppress cluster roots (Gilbert etal. 2000 Neumann et al. 2000). Cytokinines might also play a role, as kinetin applied to the growth medium of P-deficient white lupin inhibited the formation of cluster roots (Neumann et al. 2000). [Pg.151]

FIGURE 8.7 Model for the role of Rhizobium- nd xnodule formation in white clover. (Redrawn from Mathesius, U., J. Exp. Bot., 52, 419, 2001. With permission of Oxford University Press.)... [Pg.420]

Hutangura, P. et al.. Auxin induction is a trigger for root gall formation caused by root-knot nematodes in white clover and is associated with the activation of the flavonoid pathway, Aust. J. Plant Physiol, 26, 221, 1999. [Pg.440]

Cytokinins were discovered in the 1950s. In combination with auxin, they control cell division, promote juvenility or slow ageing and induce the formation of lateral buds (Figure 5.3). [Pg.117]

Ethylene is now considered to be one of the main plant-hormones involved in fruit development. Many responses formerly believed to result from the presence of auxins are now ascribed to induced ethylene production.425 The biosynthetic pathway for formation of ethylene from methionine, in a wide variety of plant tissues, including shoots of mung bean,426 tomato,427 and pea427 carrot427 and tomato428 roots and the fruits of apple,429,430 tomato,427 and avocado,427 has been elucidated, and is as follows. [Pg.343]

The formation of ethylene is often induced by the hormone auxin (Chapter 30), which stimulates activity of the synthase that forms 1-aminocyclopropane-1-carboxylate (ACC) from S-adenosyl methionine (Eq. 14-27, step j Fig. 24-16).320a/b Although ACC has... [Pg.1390]

Cloning. Asexual propagation (cloning) of plants ordinarily occurs by virture of the ability of embryonic meristematic tissue to differentiate into roots and shoots. If isolated phloem cells or other more differentiated cells are cultured, the result is often the formation of a callus, a dedifferentiated mass of cells somewhat reminiscent of embryonic cells. Under proper conditions, e.g., in a coconut milk culture and in the presence of the correct auxin-to-cytokinin ratio, some carrot root phloem cells revert to embyronic cells and develop into intact plants.99 This experiment provided proof that the differentiated carrot phloem cells... [Pg.1885]

The shikimate/arogenate pathway leads to the formation of three aromatic amino acids L-phenylalanine, L-tyrosine, and L-tryptophane. This amino acids are precursors of certain homones (auxins) and of several secondary compounds, including phenolics [6,7]. One shikimate/arogenate is thought to be located in chloroplasts in which the aromatic amino acids are produced mainly for protein biosynthesis, whereas the second is probably membrane associated in the cytosol, in which L-phenylalanine is also produced for the formation of the phenylpropanoids [7]. Once L-phenylalanine has been synthesized, the pathway called phenylalanine/hydroxycinnamate begins, this being defined as "general phenylpropanoid metabolism" [7]. [Pg.652]

Note elongation of treated clusters and formation of shot berries Endogenous Gibberellin and Auxin... [Pg.91]

The formation of plant cellulases has been found to be closely regulated by different growth hormones, particularly auxin (6,11), steroids (12), or ethylene gas (13). The hormones act in different tissues under different circumstances, and they seldom lead to such high cellulase activity that there is a net decline in total cellulose. Indeed, cellulose biosynthesis usually continues even while partial hydrolysis occurs, and net cellulose deposition often keeps pace with growth under all of these conditions (14). [Pg.344]

Leyser, O., 2005, Auxin distribution and plant pattern formation how many angels can dance on the point of PIN , Cell 121 819-822. [Pg.61]

Mathesius U, Schlaman FIRM, Spaink PIP, Sautter C, Rolfe BG, Djordjevic MA. 1998. Auxin transport inhibition precedes root nodule formation in white clover roots and is regulated by flavonoids and derivatives of chitin oligosaccharides. Plant J 14 23-34. [Pg.549]

Wasson AP, Pellerone FI, Mathesius U. 2006. Silencing the flavonoid pathway in Medicago truncatula inhibits root nodule formation and prevents auxin transport regulation by rhizobia. Plant Cell 18 1617-1629. [Pg.561]


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See also in sourсe #XX -- [ Pg.248 ]

See also in sourсe #XX -- [ Pg.680 ]

See also in sourсe #XX -- [ Pg.680 ]




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