Studies On The Characteristics Of Starch Synthesis And Enzymatic Mechanism In Different Types Of Maize

Four different maize types, normal corn, waxy corn, pop corn and sweet corn were used in the present study. The changes of starch accumulation and enzymes activities associated with starch biosynthesis in developing maize kernels were investigated by the physiological and biochemical method. The starch granule diameter, pasting properties, thermal properties and crystallization were determined by dint of the optical microscope, centrifuge, Rapid Viso-Anaylzer (RVA), Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD), respectively. The endosperm cell number, the size, shape, structure of starch granules and the development and proliferation of amyloplast were observed and compared with the optical microscope, Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM), respectively. The main results were as follows.1 Comparison on Starch Accumulation and Enzyme Activities Responsible for Starch Biosynthesis in Developing Grains of Different Maize TypesThe relationships between the rates of starch accumulation and sucrose content, the activities of enzymes responsible for starch biosynthesis in developing grains of normal corn, waxy corn, pop corn and sweet corn were investigated and compared throughout the grain filling period. The results indicated that the rates of starch accumulation and the activities of sucrose synthase (SS, degradation direction), soluble starch synthase (SSS), granule-bound starch synthase (GBSS), starch branching enzyme (SBE) and starch debranching enzyme (DBE) exhibited a single peak during grain filling period. Normal corn showed significantly...