Chalky rice has an undesirable appearance and reduced commercial value. To understand the relationship between starch structural characteristics and chalkiness, a comprehensive investigation was conducted of molecular structural differences between starch in chalky and translucent parts of the same chalky grains (three Japonica and two Indica rices), this strategy being such as to minimize genetic and environmental effects. Compared to translucent parts, chalky parts had a larger ratio of large to small branched molecules and more short amylopectin chains (degree of polymerization < 35), but fewer longer chains, which affect higher-level starch structures, such as crystallinity. No significant differences in amylose structure were observed. White-belly and white-core chalky grains showed distinguishable starch characteristics, suggesting studying different chalkiness types separately. These findings extend understanding of chalkiness from the perspective of starch structure, and control of this structure can in the future help breeders to develop strategies against the formation of chalkiness.

白垩米外观不理想，商业价值降低。为了解淀粉结构特征与白垩质之间的关系，对同一白垩质谷物（三种粳米和两种籼稻）的白垩质和半透明部分中淀粉的分子结构差异进行了全面调查，该策略旨在最大限度地减少遗传和环境影响。与半透明部分相比，白垩部分的大小支链分子比例更大，支链淀粉链更短（聚合度 < 35），但较长的链较少，这会影响更高层次的淀粉结构，例如结晶度。未观察到直链淀粉结构的显着差异。白腹和白芯白垩粒表现出明显的淀粉特征，建议分别研究不同的垩白类型。这些发现从淀粉结构的角度扩展了对白垩质的理解，并且控制这种结构可以在未来帮助育种者制定防止白垩质形成的策略。