Aleurone vacuoles

Spatial separation of carbohydrases within the cell must also be considered if the contentions of Matile [95] are correct. Matile suggests that the pea protein bodies (aleurone vacuoles), which store protein and phytin in the dry seed, become lysosomal when their reserves are depleted, and contain hydrolases (including ribonucleases, phosphatases, proteinases). Furthermore, he contends that a-amylase (and presumably the amylopectin-l,6-glucosidase) act as free enzymes in the cytoplasm and that the products of a-amylolysis then pass into the vacuole/lysosome for completion of the digestion process. While such a suggestion is appealing, it is still far from proven. 

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).

Judged by enzyme induction, Menary and Jones (1972) indicated that nitrate was unable to move from a storage pool (vacuole) to the cytoplasm of ripe paw paw fruit. Using a modified in vivo assay, Ferrari et al. (1973) estimated sizes of active (metabolic) and inactive (storage) pools of nitrate in tobacco cells, barley aleurone layers and maize leaves. The location and nature of the pools was not defined. 

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