Aleurone grain

Aleuron-kom, m. Bot.) aleurone grain -schicht, /. Bot.) aleurone layer. 

Sobolev, A.M., Buzulukova, N.P., Dmitrieva, M.I., and Barbashova, A.K., 1976, Structural-biochemical organization of aleurone grains in yellow lupin. Soviet Plant Physiol. 23 739-746. 

Takahashi, H., Rai, M., Kitagawa, T., Morita, S., Masumura,T., and Tanaka, K., 2004, Differential localization of tonoplast intrinsic proteins on the membrane of protein body type II and aleurone grain in rice seeds. Biosci. Biotchnol. Biochem. 68 1728-1736. 

The globulins (phytoglobulins) frequently occur in bodies called aleurone grains. ... 

Fig. 39.—To show aleurone grains. A, cells from cotyledon of seed of garden bean , aleurone grains m, starch B, cells from endosperm of castor bean a a, aleurone grain I, ground substance k, phytoglobulin i, globoid. A, After Sachs B, after Frank.)...

Ciys talloid.—A protein body found in the aleurone grains of seeds or underground parts. 

Glo boids.—Small granules of calcium-magnesium phosphate found in aleurone grains... 

Fig. 10. A. Cell from germinating tobacco embryo treated with iodine in KI. The aleurone grains are breaking down and the protein reaction is replaced in some by the fine-grained alkaloid precipitate. B —> D. Cells from the procambial strand similarly treated showing development of the alkaloid-containing vacuole. After Chase (13).

Fig. 9. (continued), (ob), a well-developed protein body (aleurone grain, ag), and starch grains (st) are present, (c) Thirty days after petal fall. Cell now packed with oil bodies (ob) as well as myrosin grains (mg), aleurone grains (ag), and starch grains (st). (Reproduced by permission of Mr. C. G. Smith and Springer Verlag from Smith, 1974.)... 

The endosperm of members of the Gramineae and certain other species (e.g. Trigonella, Fagopyrum) is characterized by the possession of an outer aleu-rone layer. As the seed begins to mature, the peripheral cells of the endosperm which cut off cells internally begin to divide anticlinically to form small cells of rectangular appearance in section. One or more layers of such cells may be produced they become fairly thick-walled, develop protein bodies called aleurone grains and, most important, remain alive, unlike for example the other endosperm cells of cereals which are dead cells packed with starch and to a lesser extent protein. 

Fig. 2.6A-E. Histology of food reserves 1. (A) Cotyledon cells of mung bean (Phaseolus aureus). From Harris and Chrispeels, 1975 [33]. (B) and (C) Electron micrographs of meso-phyll cell and epidermal cells (B) and protein body (C) of squash (Cucurbita maxima) cotyledons. From Lott et al., 1971 [46]. (D) and (E) Electron micrographs of a barley Hordeum vulgare) aleurone cell with aleurone grains (D) and aleurone grain (E). From Jacobsen et al., 1971 [40]. C crystalloid, G globoid, GC globoid cavity, PCB protein carbohydrate body, PB,pb protein body, PM protein matrix. Land S oil bodies, A and n nucleus, st starch grains...

Fig. 2.7A-C. Histology of food reserves 2. (A) Electron micrograph of castor bean (Ricinus communis) endosperm cell. From Vigil, 1970 [72]. (B) Electron micrograph of cotyledon cell of Sinapis alba. From Rest and Vaughan, 1972 [62]. (C) Electron micrograph of cotyledon cell of Sinapis alba. From Werker and Vaughan, 1974 [73]. AG,alg aleurone grains (protein bodies), G globoid, mg my rosin grains (presumed to contain the enzyme myrosi-nase), PB protein body, S, s oil bodies, CIV cell wall...

When we look at the amino acid compositions of the proteins from starchy endosperm and aleurone layers (Sect. 2.1.2) we can get some indication as to how the different kinds of protein are distributed within the kernel (Table 2.6). In wheat, the aleurone layer protein is clearly different from that in the remainder of the endosperm, being extremely rich in arginine this could reflect a high globulin level. Rice aleurone grains, however, are rich in albumins [69]. 

Table 2.6. Amino acid composition of protein from starchy endosperm and aleurone grains of wheat cv. Manitoba...

Sub-cellular bodies consisting of protein were first isolated from certain oil seeds by Hartig in 1855 [34]. He called these protein bodies aleurone grains... 

Phytin content of whole seeds and protein bodies varies with species and cultivar. Examples of the chemical composition of the aleurone grains of rice and protein bodies (and isolated globoids) of cotton seed are shown in Table 2.7. Note, in particular, the higher phosphorus but lower protein content of the cereal aleurone grain in comparison with the dicot protein body. The concentration of the associated macronutrient elements can also be seen to differ. Qualitative as well as quantitative differences occur between the macronutrient compositions of different seeds, e.g. in C. maxima the globoid is rich in phosphate, potassium... 

The Structure of Seeds and Their Food Reserves Table 2.7. Chemical composition of globoids and protein bodies from cotton seed and aleurone grains from rice ... 

Composition Globoid (weight %) Protein body (weight %) Aleurone grain (weight %)... 

Phosphate is stored in the mature seed as phytic acid, which is the hexaphospho-ric ester of myo-inositol —see Chapter 2. This combines with potassium, calcium and magnesium to form the salt called phytin. Accumulation of phytin in cereals is almost exclusively in the aleurone grains of the aleurone layer where it is deposited as a discrete globoid in association with protein. The precise mechanism of phytin deposition and the enzymes involved therein have been little studied and will receive no more attention here. The importance of phytin as a phosphate reserve is discussed in Chapter 6. 

As outlined earlier (Chap. 2) reserve proteins are stored in two separate sites in the cereal grain in the aleurone grains (bodies) of the aleurone layer, and in the protein bodies (sometimes disrupted) of the endosperm. Proteolysis within... 

A phytase has been isolated from the protein bodies of whole, milled, ungerminated barley, and this enzyme appears to be associated with the protein bodies of the aleurone layer (aleurone grains), a known storage site of phytin [141]. There is strong evidence (e.g. in wheat and rice) against the association... 

The 8-h lag period after GA addition is followed by a 16-(or more) h period of rapid a-amylase synthesis (Fig. 7.1 A). More ultrastructural changes are said to occur in the aleurone cells during this time [66]. These include further proliferation of the RER, distention of the RER cisternae, continued reduction in the size of the aleurone grains, decreases in the number of oil bodies, an increase in the number of plastids, and loss of the phytin globoid. 

Although GA-induced de novo synthesis and release of proteinase shows characteristics which are remarkably similar to those of a-amylase (Fig. 7.5A and B), the level of proteinase is some 30-fold less than that of a-amylase. The role of this proteinase in the hydrolysis of protein reserves within the aleurone grains and endosperm is still not fully understood. As we have already... 

---