Seeds dicotyledonous plants

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). 

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 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. 

Potato type II (Potll) inhibitors are disulfide-rich peptides of approximately 50 amino acids in size. They were first discovered in leaves, seeds, and other organs of Solanaceae and are a source of much interest as plant defense proteins. Recently, Barta et analyzed expressed sequence tag (EST) and genomic data and discovered 11 genes that code for Potll inhibitors in various monocotyledonous and dicotyledonous plants. Potll inhibitors are expressed as large precursor proteins that contain up to eight sequence repeats of the inhibitor precursor. In one particularly fascinating case from the ornamental tobacco (N. data), the precursor adopts a circular permuted structure.Barta et al. observed that genes outside the Solanaceae family seem... 

Steiner U et al., Molecular characterization of a seed transmitted clavicipitaceous fungus occurring on dicotyledoneous plants (Convolvulaceae), Planta 224 533— 544, 2006. 

Steiner, U., Ahimsa-Muller, M. A., Markert, A., Kucht, S., Gross, ]., Kauf, N., Kuzma, M., Zych, M., Lamshoft, M., Furmanowa, M., Knoop, V., Drewke, C. and Leistner, E. (2006) Molecular characterization of a seed transmitted clavicipitaceous fungus occurring on dicotyledoneous plants (Gonvolvulaceae). Planta, 224, 533-44. 

Steiner U, Ahimsa-Muller MA, Markert A, Kucht S, Gross J, Kauf N, Kuzma M, Zych M, Lamshoft M, Fttrmanowa M, Knoop V, Drewke C, Leistner E. Molecular characterization of a seed transmitted clavicipitaceous fungus occitrring on dicotyledoneous plants (Convolvulaceae). Planta. 2006 224 533-544. 

Pig. 172.—Morphology of a typical dicotyledonous plant. A, leaf, pinnately-netted veined B, portion of stem, showing concentric layers of wood C. ground-plan of flower (the parts in 5 s) D, perspective of flower E, longitudinal section of seed, showing dicotyledonous embryo. Gager,)... 

Herbicidins. Five adenine nucleosides, herbicidins A, B, E, F, and G (30—34), have been isolated from the culture filtrates of S. sagamonensis No. 4075 (1,4) which also produces ara-A and 2 -deoxycoformycin. The herbicidins contain a tricyclic dodecose. They inhibit dicotyledonous plants, germination of plant seeds, growth of blue-green algae, and fungi. 

Plant acetyl CoA carboxylase [EC 6.4.1.3] is one of the pivotal enzymes of fatty acid biosynthesis in both seed and leaf tissue and is thought to be an important regulatory step of de novo fatty acid synthesis in chloroplasts (Post Beittenmiller et al., 1992). Its central role reflects its importance as a target for commercial herbicides. Two forms of ACCase are present in dicot plants. The chloroplast is thought to be the site for de novo fatty acid synthesis in mesophyll cells and BCCP has been shown to reside within the chloroplast. It is therefore reasonable to suppose that a type II Brassica napus ACCase is mainly associated with de novo lipid synthesis. Specific herbicides differentiate between the two forms of acetyl CoA carboxylase (ACCase) found in dicotyledonous plants. 

Nature in its abundance offers us a lot of material that can be called fibrous fibres are found in plant leaves, fraits, seed covers and stalk. Fibres from these plants can be considered to be totally renewable and biodegradable. Bast fibres are soft, woody fibres obtained from stems of dicotyledonous plants (flowering plants with net-veined leaves). Such fibres, usually characterized by fineness and flexibility, are also known as soft fibres, distinguishing them from the coarser, less flexible fibres of the leaf, or hard , fibre group. This chapter will discuss bast fibres from flax, hemp, jute, ramie, kenaf and abaca. 

The herbicidal activities of hydantocidin and comexistin against dicotyledonous plants are shown in Table 3. Hydantocidin and comexistin also had potent herbicidal activities against dicotyledonous plants, but the killing effects on these plants were non-selective. One notable exception was that of corn seedings which were able to tolerate comexistin. 

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]. 

The biosynthesis pathway of GAs in plants has long been studied since their discovery as endogenous growth regulators. There have been two key approaches to unravel the biosynthetic routes and identify the genes encoding the biosynthetic enzymes. First, a cell-free system prepared from immature seeds of dicotyledonous species such as Marah macrocarpus and Cucurbita maxima allowed researchers to purify and characterize the GA... 

The use of seed-specific promoters appears to be the most promising (see Table 6.1). Seeds are also an attractive choice for molecular farming because they can be transported and stored for downstream processing, without any significant loss of yield or quality of the recombinant protein. Several seed-specific promoters from dicotyledonous and monocotyledonous plants have been isolated and used for expression of recombinant proteins in rice [32, 33], com [34—36], barley [14], wheat [37], tobacco [13], and even Arabidopsis [38]. The yield of recombinant proteins in seeds can reach up to 45% of TSP, as was shown in... 

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