Role in plants

As pointed out recently by Zucker (153), the role of plant tannins at the ecological level is almost certainly a mixed function, involving a defense mechanism against living plant enemies and inhibition of decomposition of plant tissue when it becomes litter, either in the soil as roots, or on the soil and leaves. There is, moreover, no compelling evidence that tannins have any role in plant physiological processes. 

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Chen, L.J. and Hrazdina, G., Structural aspects of anthocyanin-flavonoid complex formation and its role in plant color. Phytochemistry, 20, 297, 1981. 

Most research on the rhizospherc environment has been forcedly descriptive in the past. Recent advances show that organic compounds present in the rhizo-sphere can have a specific role in plant-micro-organism-soil interactions. Moreover, it starts to be elucidated ... 

Fresh organic matter plays a fundamental role in plant nutrition by supplying nutrients released through degradation processes however, humified organic substances also become a source of nutrients when subjected to mineralization processes. The main aspects of the cycle of organic matter at the rhizosphere soil are reported in Chap. 6. 

Kolattukudy PE (1987) Lipid derived defensive polymers and waxes and their role in plant-microbe interaction. In Stumpf PK (ed) The biochemistry of plants vol 9 - lipids structure and function. Academic Press, New York, p 291... 

Calcium oxalate (723) occurs as the monohydrate (whewellite, the thermodynamically stable form under ambient conditions (724)), the dihydrate (weddellite) in plant calcium stores and in sap, or the trihydrate (725). Calcium oxalate also plays a structural role in plants. Oxalate, for example from excessive amounts of rhubarb or spinach, inhibits absorption of Ca2+ from the GIT precipitation of calcium oxalate is the reason for the toxicity of oxalates. Calcium oxalate may also occur in man, where it can appear as minute star-shaped crystals in the urine. It is the main constituent of the majority of urinary calculi in man (726,727). The relationships between dietary calcium... 

WALDEN, R., FRITZE, K HAYASHI., H., MIKLASHEVICHS, E., HARLING, H., SCHELL, J., Activation tagging a means of isolating genes implicated as playing a role in plant growth and development, Plant Mol. Biol., 1994,26, 1521-1528. 

Salutaridinol 7-0-acetyltransferase catalyzes the conversion of the phenanthrene alkaloid salutaridinol to salutaridinol-7-Oacetate, the immediate precursor of thebaine along the morphine biosynthetic pathway in P. somniferum (Fig. 10.7).26 Acetyl CoA-dependent acetyltransferases have an important role in plant alkaloid metabolism. They are involved in the synthesis of monoterpenoid indole alkaloids in medicinal plant species such as Rauwolfia serpentina. In this plant, the enzyme vinorine synthase transfers an acetyl group from acetyl CoA to 16-epi-vellosimine to form vinorine. This acetyl transfer is accompanied by a concomitant skeletal rearrangement from the sarpagan- to the ajmalan-type (reviewed in2). An acetyl CoA-dependent acetyltransferase also participates in vindoline biosynthesis in Catharanthus roseus, the source of the chemotherapeutic dimeric indole alkaloid vinblastine (reviewed in2). Acetyl CoA deacetylvindoline 4-O-acetyltransferase catalyzes the last step in vindoline biosynthesis. A cDNA encoding acetyl CoA deacetylvindoline 4-0-acetyltransferase was recently successfully isolated.27... 

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