Plants dicotyledons

Plant iron uptake can be divided into two distinct families, with quite distinct strategies. Strategy I plants reduce Fe + to Fe + outside of the roots, and then take up the Fe +. In contrast. Strategy II plants solubilise Fe + by excreting Fe +phytosiderophores, which are taken up by specihc transporters and the iron is then reduced to Fe " " in the symplasm of the root cell (Fig. 7.14). In Strategy I plants, (dicotyledons such as Arabidopsis pea. 

Fig. 3. The scheme of the precipitates formed by the crude protein extracts of plants of the groups monocotyledons (1-11, table 1) and dicotyledons (12-23 table 1) with antibodies against wheat chitin-binding proteins (I) and with antibodies against wheat anionic PO (H).

Bate-Smith, E. C. 1962. The phenolic constituents of plants and their taxonomic significance. I. Dicotyledons. J. Linn. Soc. Bot. 58 95-173. 

F. Shinmachi, I. Flasegawa, A. Noguchi, and J. Yazaki, Characterization of iron deficiency response system with riboflavin secretion in some dicotyledonous plants. Plant Nutrition for Sustainable Food Production and Environment (T, Ando, K. Fujita, T. Mae, H. Mat.sumoto, S. Mori, and J. Sekiya, eds.), Kluwer Academic Publishers, Dordrecht, 1997, p. 277. 

Especially in dicotyledonous plant species such as tomato, chickpea, and white lupin (82,111), with a high cation/anion uptake ratio, PEPC-mediated biosynthesis of carboxylates may also be linked to excessive net uptake of cations due to inhibition of uptake and assimilation of nitrate under P-deficient conditions (Fig. 5) (17,111,115). Excess uptake of cations is balanced by enhanced net re-lea,se of protons (82,111,116), provided by increased bio.synthesis of organic acids via PEPC as a constituent of the intracellular pH-stat mechanism (117). In these plants, P deficiency-mediated proton extrusion leads to rhizosphere acidification, which can contribute to the. solubilization of acid soluble Ca phosphates in calcareous soils (Fig. 5) (34,118,119). In some species (e.g., chickpea, white lupin, oil-seed rape, buckwheat), the enhanced net release of protons is associated with increased exudation of carboxylates, whereas in tomato, carboxylate exudation was negligible despite intense proton extrusion (82,120). 

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... 

The use of microbial siderophores by dicotyledonous plants appears to involve uptake of the entire metallated chelate (42-44), or an indirect process in which the siderophore undergoes degradation to release iron (45). As demonstrated in initial studies examining this question, there was concern that iron uptake from microbial siderophores may be an artifact of microbial iron uptake in which radiolabeled iron is accumulated by root-colonizing microorganisms (46). Consequently, evidence for direct uptake of iron from microbial siderophores has required the use of axenic plants. In experiments with cucumber, it was shown that the microbial siderophore ferrioxamine B could be used as an iron source at concentrations as low as 5 pM and that the siderophore itself entered the plant (42). 

The latter substance, as is well known, interferes with nuclear division in plants. Temple-man and Sexton (35) showed that, contrary to the effects of the phenoxyacetic acids, the arylurethanes destroy cereals more readily than the dicotyledonous plants. 

I The distinction between mono-and dicotyledonous plants is quite simple monocotyledons are flowering plants which have only one seed leaf, and usually have parallel-veined leaves, flower parts in multiples of three, and no secondary growth in stems and roots, whereas dicotyledons are flowering plants with two seed leaves (cotyledons), net-veined leaves, flower parts in fours and fives, and in woody plants have cambium, a layer of formative cells between the wood and the bark the cells increase by division and differentiate to form new wood and bark. 

The objective of this paper was to investigate the anticlastogenic and antitoxic effects exerted by HS of various origin and nature on several monocotyledon and dicotyledon herbaceous plant species treated with different mutagenic and phytotoxic compounds. 

The seeds of dicotyledonous plants have two cotyledons, or seed leaves, which are part of the embryo. The cotyledons usually are the main storage tissue, although in some plants (such as castor bean) the endosperm also has a storage function. During development in the field, seeds gradually accumulate storage oils, proteins and carbohydrates (Table 3.1). In the seed, the cotyledon structure is relatively simple. The remainder of the embryo, the embryonic axis, consists mostly of undifferentiated cells, but provascular tissue can be detected that develops into vascular tissue in the seedling. 

In the quest to find other plants that are suitable as bioreactors, various monocoty-ledonous and dicotyledonous species have been tested. These include corn [16], rice and wheat [17], alfalfa [18], potato [19, 20], oilseed rape [21], pea [22], tomato [23] and soybean [24]. The major advantage of cereal crops is that recombinant proteins can be directed to accumulate in seeds, which are evolutionar specialized for storage and thus protect proteins from proteolytic degradation. Recombinant proteins are reported to remain stable in seeds for up to five months at room temperature [17] and for at least three years at refrigerator temperature without significant loss of activity [25]. In addition, the seed proteome is less complex than the leaf proteome, which makes purification quicker and more economical [26]. 

Fry SC, Miller JG. Toward a working model of the growing plant cell wall. Phenolic cross-linking reactions in the primary cell walls of dicotyledons. American Chemical Society, Washington, DC, 1989. 

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