Cotyledon protein

Fig. 1. Transmission electron micrograph of a section of a mature, hydrated soybean cotyledon. Protein bodies (PB), lipid bodies (LB), and cell wall (CW)...

FIGURE 2.3 SEM micrograph of parenchymal tissue from raw almond cotyledon. Protein bodies (p) and lipid bodies (1) in cytoplasmic network. 

Immunohistochemistry also shows that a protein which cross reacts with antibody raised against the cotyledon 62 kD protein exists in leaves. The cross reacting protein is localized primarily in three cell types of the phloem of mature leaves. Studies at the electron microscope level further show that the intra-cellular localization is again exclusively in the outer membrane of the cells. While these unpublished results do not prove that the 62 kD cotyledon protein is a sucrose carrier, they are very encouraging and may prove very useful in studying the developmental regulation of this transport process as well as providing the further tools needed to definitively identify the carrier protein. 

It must be realized, however, that reserves are frequently present in some measure throughout the whole seed. In lettuce, for example, though most of the protein and oil stores are located in the cotyledons, protein and oil bodies nevertheless do occur in the radicle/hypocotyl region. Additionally the endo-... 

Fig. 6.18. Changes in protein and amino acid content in the cotyledons and axis of dark-grown Alaska pea seedlings, o—o protein content of cotyledons — protein content...

If, however, the chromatin of the cotyledons and apical buds is deproteinized and only the DNA templates are used for synthesis of RNA and protein, the differences in specificity between the synthesized products disappear, but the relative globulin content in the proteins synthesized by cotyledon DNA falls from 7 to 0.4%, whereas in the products synthesized on DNA of the apical buds, it increases from 0.1 to 0.4-0.5%. This is natural, because in deproteinized DNA all the genes are active and derepressed. Whereas in the case of cotyledon DNA this leads to a decrease in the relative volume of the DNA templates for synthesis of RNA templates for the cotyledon proteins, in the case of DNA of the apical buds, however, it depresses the gene for synthesis of cotyledon protein. 

Seeds. Seeds are produced in pods, usually containing three almost spherical-to-oval seeds weighing 0.1—0.2 g. Commercial varieties have a yellow seed coat plus two cotyledons, plumule, and hypocotyl-radicle axis. The cotyledons contain primarily protein and Hpid bodies (see Fig. 1). Cottonseed. 

Seeds. The seeds are produced in pods containing two or three seeds. The kernels are almost spherical to roughly cylindrical (0.4—1.1 g each) and consist of a thin coat (testa) containing two cotyledons and the embryo. Cotyledons contain protein bodies, Hpid bodies, and starch granules. 

Millichip, M. et al.. Purification and characterization of oil-bodies (oleosomes) and oil-body boundary proteins (oleosins) from the developing cotyledons of sunflower (Helianthus annuus L.), Biochem. J., 314, 333, 1996. 

Figure 2 show that the specific activity fi om the cotyledons (mean value 38,200 and 13,900 dpm mg protein at pH 5.5 and 7 repectively) was also larger than from hypocotyls (21,300 and 7,500) or roots (18,600 and 10,500). Whatever the pH, two peaks occured in the cotyledons (days 3 and 9) while the specific activity was slightly increasing in the roots, during the culture. In the hypocotyls, the activity was rather constant at pH 5.5 and presented two peaks at neutral pH. In all cases, the specific activity was larger than that of suspension-cultured cells which had been estimated in the range of 250 and 2500 dpm mg" protein. 

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. 

Microbodies (97-101) are spherical organelles (0.1-2.0 pm in diameter) bounded by a single membrane. They possess a granular interior and sometimes crystalline protein body. A specialized type of microbody is the glyoxysome (0.5-1.5 pm) containing enzymes ofthe glyoxy-late cycle. Glyoxysomes are found in the endosperm or cotyledons of oily or fatty seeds. 

Figure 1. Scanning electron micrograph of Phaseolus vulgaris cotyledon showing protein bodies (P) and starch granules (S). Bar = 10 dm.

Grain legumes have also been processed into refined starch (10,11) and protein isolates (12,13,14) by procedures derived from the traditional corn starch and soybean protein industries (15). However, comparative data on product yields, composition and losses have not been published. A commercial plant for the wet processing of field pea into refined starch, protein isolate and refined fiber has been established in Western Canada. Little is known about the characteristics of the protein isolate or refined fiber product. Water-washed starch prepared from the air-classified starch fractions of field pea (16,17) and fababean (6) have been investigated for certain physico-chemical and pasting properties. Reichert (18) isolated the cell wall material from soaked field pea cotyledons and determined its fiber composition and water absorption capacity. In addition, the effects of drying techniques on the characteristics of pea protein Isolates have been determined (14). 

Hull Cotyledon High Protein High Starch... 

Figure 2. Scanning electron micrograph of a mesophyll cell of a dormant cotyledon of Buffalo gourd (Cucurbita foetidissima). Tissue was fixed in aqueous glutaraldehyde, dehydrated with ethanol and critically point dried. Note cell wall (W) and intracellular components including protein bodies (P) and emptied spherosomes that appear as a cytoplasmic reticulum.

Figure 3. Transmission electron micrographs of mesophyll cells of dormant cotyledons of A, Cucurbita foetidissima B, Cucurbita pepo C, Cucurbita palmata D, Cucurbita digitata E, Apodanthera undulata" Note cell wall (W), protein body (P), spherosome (S), globoid (G), and crystalloid (X). In each micrograph, the bar represents five microns. Reproduced from reference 14.

Figure 2. Effect of ozone on uptake and incorporation of -leucine into protein by cotton cotyledon leaf discs. Plants were exposed to 0.4 ppm Os for 1 hr, 24 hr prior to experiments. Discs were floated on buffer and incubated in -leucine for up to 4 hr and were then transferred to excess cold leucine to chase the incorporated C-leucine for a subsequent 24 hr period. The data show that ozone-treated tissue incorporated more leucine into protein but do not indicate real differential effects on protein hydrolysis.

Soybeans grow on a bushy, annual plant ranging in height from about 30 to 50 inches (75 to 125 cm). Stems have a hairlike covering and leaves are trifoliated. Flowers range in color from white to purple with variations in-between. Seedpods usually contain three spherical to oval seeds weighing 0.1 to 0.2 g. Most seeds have a yellow coat containing two oil- and protein-rich cotyledons. 

FIGURE 10-3 Fat stores in cells, (a) Cross section of four guinea pig adipocytes, showing huge fat droplets that virtually fill the cells. Also visible are several capillaries in cross section, (b) Cross section of a cotyledon cell from a seed of the plant Arabidopsis. The large dark structures are protein bodies, which are surrounded by stored oils in the light-colored oil bodies. 

Ihl, M. Indole-acetic acid binding proteins in soybean cotyledon. Planta, 1976, 131, 223-228. 

---