Peripheral Endosperm

Watson, S.A., Sanders, E.H., Wakely, R.D., and Williams, C.B. 1955. Peripheral cells of the endosperms of grain sorghum and corn and their influence on starch purification. Cereal Chem. 32 165-170. 

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. 

Connected with the controversial views on the origin of the oil bodies is the question as to whether they are bounded by membranes. Evidence for and against the existence of some kind of peripheral membrane is presented in Section 3.3.8. We should note, in addition, favourable evidence for an oil body membrane raised by the freeze-fracture studies on barley aleurone cells [20 b] and by biochemical analyses of peanut and walnut oil bodies which reveal phospholipid and protein characteristic of membranes. Finally, we should be aware that in addition to the possible existence of membrane protein, enzyme protein may also occur in oil bodies. Enzymes for fatty acid biosynthesis have been reported in oil bodies of developing castor bean [35] and for triglyceride hydrolysis (acid lipases) in the mature endosperm of this species the latter enzymes may not occur in oil bodies of other species (Chap. 6). 

Cross Cells Tube Cells Testa Aleurone Layer Peripheral endosperm... 

FIGURE 4.3 Microphotograph detailing the microstructure of the pericarp and aleurone layer of the sorghum caryopsis. E = epicarp M = mesocarp S = starch granules CC = epicarp cross cells T = epicarp tube cells SC = seed coat or testa A = aleurone cells P = peripheral endosperm (courtesy of C. McDonough and L. W. Rooney, Texas A M University). 

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