Membranes aleurone layer

The process of infection of lupine nodule cells by Rhizobia was examined by the thin-section electron microscopic technique, as well as the freeze-fracture technique. Different membranes such as infection thread membranes, peribacterioid membranes, plasma membranes, membranes of cytoplasmic vesicles, and membranes of the Golgi bodies and ER were stained with uranium-lead, silver, phosphotungstic acid, and ZIO (31). ZIO stained the membranes of the proximal face of the Golgi bodies and endoplasmic reticulum. ZIO staining has given good contrast in thick sections such as a cotyledon cell, a root cell, and an aleurone layer for ER, dictyosomes cisternae, mitochondria, and nuclear envelopes (17,32-37). 

Both gel filtration and centrifugation have been used to examine the distribution of a-amylase activity in homogenates of barley aleurone layers following incubation with gibberellic acid. The results support the view that a-amylase is secreted by membrane-bound vesicles. The amount of a-amylase retained by the cell wall is influenced by the buffer in which the layers are incubated and by the presence of actinomycin D. 

Most phosphorus associated with cereal grains exists in the form of phytic acid (myoinositol hexaphosphate) that is stored in phytic bodies mainly loeated in the aleurone layer. These molecules bind potassium, magnesium, and other minerals. The phytases degrade these compounds to release phosphate, other minerals, and myoinositol. The myoinositol is a known precursor of sugars associated with cell wall polysaccharides and a promoter of seedling growth. The free phosphorus is critically important for synthesis of nucleic acids and phospholipids for cellular membrane proliferation, and ATP and energy production. 

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