Abstract:

Objective Separating high-quality leaf starch is conducive to studying the physicochemical properties and developmental regulation mechanisms of leaf starch. The separation of rice leaf starch using reported leaf starch extraction methods is complicated, requires high operational requirements, and the purity of the separated rice leaf starch is not high. Therefore, it is necessary to establish a method suitable for extracting starch from rice leaves. Method We optimized and obtained a simple method for separating and purifying rice leaf starch, which mainly includes nine steps: leaf grinding, cell splitting, starch release, filtration, impurity removal, standing sedimentation, starch washing, ethanol dehydration and drying preservation. The improvement of this method lies in using standing sedimentation to replace the centrifugal collection of starch in Arabidopsis leaf starch extraction method, which can effectively separate rice leaf starch through 3 times of suspension settling. Result Using this method to separate and purify starch from three types of rice leaves, the purity of starch in the precipitation reached 87%. Compared with the polygonal shape of endosperm starch granules, the leaf starch granules were flat and long ellipsoidal, whose size were significantly smaller than that of endosperm starch granules in rice. The thermodynamic property assay showed that the gelatinization onset temperature, gelatinization peak temperature and gelatinization completion temperature of leaf starch were significantly higher than those of endosperm starch, while the gelatinization enthalpy was lower than that of endosperm starch in rice. Conclusion The optimized method for separating and purifying rice leaf starch is simple and environment-friendly, by which the high-purity leaf starch is obtained for the study of starch morphology and physicochemical properties.

Key words: rice, leaf starch, starch granule, starch purification, starch morphology