Immunocytochemical Location Of ADP-Glucose Pyrophosphorylase (AGPase) And β-Amylase In Tuberous Root Of Sweet Potato(Ipomoea Batatas Lam.)

The mainly substance in tuberous root in sweet potato is starch. How to improve the content of starch in tuberous root is one of important tasks in sweet potato breeding. AGPase converts Glc-l-P and ATP-Glc and PPi. The product of this reaction, ADP-Glc, is the major substrate for starch synthases. AGPase catalyzes an essential step for starch biosynthesis in both photosynthetic and nonphotosynthetic tissues in higher plants.In this experiment, Subceilular localization of ADP Glucose Pyrophosphorylase (AGPase) in developing tuberous roots of sweet potatoes has been investigated by immunolocalization for the first time. The results are helpful to understand the mechanism of starch metabolism in the tuberous root of sweet potato and cultivate varieties of high starch content. The mainly results as follows:l.The enzyme is localized in cytoplasm as well as amyioplast at electron microscope level. The immunogold particles in amyioplast are mainly localized at the periphery of starch granules. The signal of AGPase has become stronger with the development of tuberous root of sweet potato. The signal in the cells of high starch content sweet potato varieties is a little stronger than that of low starch content sweet potato varieties at the same developmental stage (at 70 days and 110 days after planting). The signal in the cells of low starch content sweet potato varieties became the strongest at 110 days after planting and became weaker gradually at 140 days; whereas, that of high starch content sweet potato varieties become stronger all the time.2.Beta-amylase is localized at the periphery of starch granules. With the development of the tuberous root of sweet potatoes, the signal became stronger.The diameter of starch granules became larger with the development of the tuberous root of sweet potatoes at the light microscope level. The whorl-like starch granules became bigger from inside to outside.Western blotting detection shows two bands of peptides (50KD and 51KD) for AGPase, with the highly specific anti-tomato AGP fruit antibody. The results above prove that the result of immunolocalization is correct.