Different effects of iron uptake and release by phytoferritin on starch granules
Tuo Zhang1, Xiayun Liao, Rui Yang
1CAU and ACC Joint-Laboratory of Space Food, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing Key Laboratory of Functional Food from Plant Resources, Beijing 100083, China.
Abstract:
Phytoferritin from legume seeds is naturally compartmentalized in amyloplasts, where iron is takem up and released by ferritin during seed formation and germination. However, the effect of these two processes on starch granules remains unknown. No starch damage was visualized by SEM during iron uptake by apo soybean seed ferritin (SSF). In contrast, great damage was observed with the starch granules during iron release from holoSSF induced by ascorbic acid. Such a difference stems from different strategies to control HO(•) chemistry during these two processes. HO(•) is hardly formed during iron uptake by apoSSF, whereas a significant amount of HO(•) is generated during iron release due to the Fenton reaction. As a result, starch granules are kept intact during iron uptake, which might beneficial to the storage of the starch granules during seed formation. In contrast, these starch granules are dramatically hydrolyzed during the iron release process, which might favor seed germination.
