薏米蒸煮品质与淀粉和蛋白质理化特性的关系及其形成的生理分子机理

Coix seed have high nutritional and medicinal value, is becoming popular among house cooking and food & medicine processing industries. However, its texture is very hard, and its starch is difficult to gelatinize, therefore it is not easy to cook under normal cooking conditions; which severely restrict its application. This research aims to evaluate genotypic variation of cooking quality of coix seed materials collected from various provinces of southwest of China, and then explain the physicochemical mechanism difference among coix seed materials which have distinct different cooking quality by analyzing its starch structure, protein properties and morphological and anatomical characteristics of its endosperm. Finally, we try to explain the physiological and molecular mechanism of cooking quality of coix seed, by analyze the dynamic changes of starch and protein accumulation related genes expression and differential protein expression profile of endosperm of coix seed materials with significant different cooking quality. The resulting work would be of significance for cultural and genetic improvement of cooking quality of coix seed, and be useful for explanation of cooking trouble of coix seed.

薏米（Coix seed）具有较高的营养价值和药用价值，近年来在家庭直接食用和药食品加工中受到更多青睐。然而，薏米质地坚硬难于蒸煮，严重制约了薏米的应用。本项目通过评价薏米蒸煮品质的基因型差异，比较蒸煮品质差异显著的薏米材料间淀粉分子结构、蛋白质组分和分子量、形态解剖学特征的区别，以期明确薏米淀粉和蛋白质理化特性与蒸煮品质的关系，解析薏米难蒸煮的关键因素。最后通过分析薏苡胚乳发育过程中的淀粉和蛋白质积累相关的关键基因表达差异，及蒸煮品质差异显著的薏米材料间蛋白组水平表达的差异，以期初步揭示薏米蒸煮品质形成的生理分子机制。该研究结果可为薏米蒸煮品质的栽培调控和遗传改良提供参考，有助于破解薏米难蒸煮这一制约薏苡产业发展的重要难题。

薏米（Coix seed）具有较高的营养价值和药用价值，近年来在家庭直接食用和药食品加工中受到更多青睐。然而，薏米质地坚硬难于蒸煮，严重制约了薏米的应用。本项目通过评价薏米蒸煮品质的基因型差异，比较蒸煮品质差异显著的薏米材料间淀粉分子结构、蛋白质组分和分子量、形态解剖学特征的区别，以期明确薏米淀粉和蛋白质理化特性与蒸煮品质的关系，解析薏米难蒸煮的关键因素。最后通过分析薏苡胚乳发育过程中的淀粉和蛋白质积累相关的关键基因表达差异，及蒸煮品质差异显著的薏米材料间蛋白组水平表达的差异，以期初步揭示薏米蒸煮品质形成的生理分子机制。本研究结果表明：（1）快速黏度分析仪可以用于薏苡蒸煮品质的快速鉴别，根据峰值黏度、冷浆黏度可基本区分薏米米粉的蒸煮难易程度，一般二者值越大越难蒸煮，米粉糊冷置质地越硬。（2）薏米的蒸煮时间长短与薏米籽粒大小正相关。（3）Y80-2为难蒸煮薏米，其直链淀粉含量高、淀粉颗粒粒径大；XR较易蒸煮，其直链淀粉含量低，是前者的1/3，长分支链淀粉含量高。（4）颖果发育前5天，薏苡胚乳营养物质积累缓慢，花后25天左右可达灌浆高峰，花后33天以后灌浆进入平台期，籽粒粒重稳定逐渐脱水完熟。花后5天和花后33天的颖果存在大量差异表达基因，差异基因主要集中与次生代谢产物。（5）易蒸煮材料XR和难蒸煮材料Y80-2，灌浆中期差异表达基因和蛋白较少，成熟期较多，主要差异表达基因和蛋白与淀粉、细胞、核糖体等生物合成途径有关。本研究结果可为薏米蒸煮品质的栽培调控和遗传改良提供参考，有助于破解薏米难蒸煮这一制约薏苡产业发展的重要难题。