Formation of storage starch in storage organs
(I) The starch formation in potato tuber
1954 Volume 67 Issue 789-790 Pages 57-62
Details
1954 Volume 67 Issue 789-790 Pages 57-62
1) The localization of phosphorylase in the potato tuber and the process of the starch formation therein were histochemically investigated.
2) In the potato tuber the presense of phosphorylase was demonstrated in all parts of the tissues where storage starch was to be formed, and furthermore in the vascular ring devoid of storage starch. The amount of the enzyme was largest in the actively growing regions, such as tips and buds of the tuber.
3) When various sugar solutions were supplied to the tuber through the cut ends of the stem, starch grains were produced within the cells. They arose from the amyloplasts lying embedded in the cytoplasm, but not from the vacuoles.
4) Among the various sugars tested, sucrose, glucose and maltose were effective for the starch formation, and the high concentration of the sugars favoured this process. From fructose and galactose, no starch was produced.
5) The storage starch grains in the beginning of its formation were still minute in size and occupied only a small part of the cell, but they became to spread into the whole inside of the cell as they grew larger.
