Plant development, phenylpropanoids

L-phenylalanine, L-a-aminooxy-g-phenylpropionic acid (AOPP, in Fig. 9) should have an increased inhibitory ability. This was confirmed beyond our expectations, as L-AOPP inhibited buckwheat PAL with a Ki of 1.4 nM (Table 2) and also inhibited the biosynthesis of phenylpropanoid compounds in vivo without deleterious effects on normal plant development. Selective accumulation of phenylalanine in... 

The functions of phenylpropanoid derivatives are as diverse as their structural variations. Phenylpropanoids serve as phytoalexins, UV protectants, insect repellents, flower pigments, and signal molecules for plant-microbe interactions. They also function as polymeric constituents of support and surface structures such as lignins and suberins [1]. Therefore, biosynthesis of phenylpropanoids has received much interest in relation to these functions. In addition, the biosynthesis of these compounds has been intensively studied because they are often chiral, and naturally occurring samples of these compounds are usually optically active. Elucidation of these enantioselective mechanisms may contribute to the development of novel biomimetic systems for enantioselective organic synthesis. 

These results, together with those of the other works described above indicate that phenylpropanoid metabolism may play an important role in the development of plant acclimation to thermal stress. 

BIOLOGICAL FUNCTION OF PHENYLPROPANOIDS IN PLANT GROWTH, DEVELOPMENT, AND INTERACTIONS WITH THE ENVIRONMENT... 

Wang, J., Dudareva, N., Bhakta, S., Raguso, R.A. and Pichersky, E. (1997) Floral scent production in Clarkia breweri (Onagraceae). II. Localization and development modulation of the enzyme S-adenosyl-L-methionine (iso)eugenol O-methyltransferase and phenylpropanoid emission. Plant Physiol., 114, 213-21. 

The phenylpropanoid pathway (Fig. 3.1) is responsible for the production of many natural products that are of interest in the context of plant growth and development, human health, and ecology. For example, flavonoids are necessary for pollen viability in maize and petunia, and have been suggested to play a role in directed auxin transport. Flavonoids and sinapate esters have been found to be important UV-protectants in many species, including Arabidopsis. Furthermore, wall-bound phenolics are thought to impart control over cell wall expansion, and hydroxycinnamic acids are an important structural component of the hydrophobic barrier polymer suberin. Finally, lignin is a phenylpropanoid polymer ubiquitous in higher plants, which is necessary for mechanical support and water transport. " ... 

Arahidopsis has become the model system of choice in which to study many aspects of plant growth, development, and metabolism, including the biosynthesis of phenylpropanoid natural products. This is, in part, because Arabidopsis accumulates two classes of phenylpropanoid end products that are good targets for mutant screens. For example, many screens have identified mutants defective in fiavonoid biosynthesis. Defects in this pathway in Arahidopsis lead to transparent testa (tt) and transparent testa glabrous (ttg) phenot3Tjes that result from decreases in the condensed tannins found in the seed coat. These mutants have already been exhaustively reviewed, and hence will not be covered here. 

Weiss M, Mikolajewski S, Peipp H, Schmitt U, Schmidt J, Wray V, Strack D (1997) Tissue-specific and development-dependent accumulation of phenylpropanoids in larch mycorrhizas. Plant Physiol 114 15-27... 

Isoflavones are synthesized as one group of end-products (iso-flavones) in the phenylpropanoid biosynthetic pathway (Fig. 60.5). They occur in highest levels in the roots, developing seedlings, and seeds of leguminous plants, but are found in lower amounts in leaves, stems, roots, and flowers of older plants. In seeds, they are... 

Chen, J.-Y., Wen, P.-R, Kong, W.-R, Pan, Q.-H., Wan, S.-B. Huang, W.-D. (2006). Changes and subcellular localizations of the enzymes involved in phenylpropanoid metabolism during grape berry development. Journal of Plant Physiology, 163, 115-127. 

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