Phenolic monocotyledonous plants

Despite increased citrate accumulation in roots of Zn-deficient rice plants, root exudation of citrate was not enhanced. However, in distinct adapted rice cultivars, enhanced release of citrate could be observed in the presence of high bicarbonate concentrations in the rooting medium, a stress factor, which is frequently associated with Fe and Zn deficiency in calcareous soils (235) (Hajibo-huid, unpublished). This bicarbonate-induced citrate exudation has been related to improved Zn acquisition in bicarbonate-tolerant and Zn-efficient rice genotypes (Fig. 9) (23S). Increased exudation of sugars, amino acids, and phenolic compounds in response to Zn deficiency has been reported for various dicotyledonous and monocotyledonous plant species and seems to be related to increased... 

Phenolic acids, and especially ferulic acid, which is abundantly present in cereals, is found esterified to the polysaccharides present in primary and secondary cell walls of plants. Ferulic acid is the major phenolic acid occurring in the cell walls of monocotyledons and appears as cis and the more abundant trans isomers (reviewed in [Klepacka and Forna, 2006]). Ferulic acid is found in wheat, maize, rye, barley [Sun et al., 2001], oats, spinach, sugar beet, and water chesnuts [Clifford, 1999], generally esterified, and rarely as free form, such as in barley [Yu et al., 2001]. It is esterified in primary cell walls to arabinoxylans (Fig. 2.4) in the aleurone layer and pericarp [Clifford, 1999], as in spinach [Fry, 1982] or in wheat bran [Smith and Hartley, 1983], Ferulic acid can also be found esterified to other hydroxycinnamic acids such as in Mongolian medicinal plants where it is found as feruloylpodospermic acid, which is... 

Proanthocyanidins are plant phenolic biopolymers that consist of flavanoid monomer units. Two major classes of proanthocyanidins occur those that possess a resorcinol-pattern A-ring (Figure 1) and those that possess a phloroglucinol-pattern A-ring. The latter are by far the most common, occurring in a high proportion of monocotyledonous and dicotyledonous plants (1,2). The resorcinol-pattern proanthocyanidins are confined to a few genera of tropical or subtropical hardwoods and associated shrubby species (2), but are economically important, since the internationally commercially predominant wattle (3,4) and quebracho... 

The polyphenolic tannins are of little importance in the lower orders of plants such as fungi, algae, and mosses, and in most of the monocotyledons such as the grasses (McLeod, 1974). Most of the tannins appear to be found in a few families of the dicotyledons such as the Leguminosae (White, 1957). Singleton and Kratzer (1969) also suggest that specific toxic phenols, and phenols with closely related structures, may be confined to certain families and not infrequently to certain genera, certain species, or even to certain varieties at certain times. Tannins are believed to occur in the vacuoles of intact plant cells (Kramer, 1955 Forsyth, 1964). 

Bate-Smith E C 1968 The phenolic constituents of plants and their taxonomic significance. 2. Monocotyledons. J Linn Soc (Bot) 60 325-356... 

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