为研究玉米种子萌发初期可溶性糖的变化和能量供应,本文以玉米品种“大白头”为实验材料,分析了吸胀0-24h种子水分、可溶性糖、糖代谢关键酶活性及其基因表达和ATP含量的动态变化。结果表明,玉米种子可溶性糖主要以蔗糖的形式贮藏于胚中；种子吸胀过程中蔗糖含量降低,同时麦芽糖、葡萄糖和果糖含量升高,并且种子吸胀8h时蔗糖的转化即已被启动。酶活性和基因定量结果表明,种子吸胀8h时,糖酵解途径和三羧酸循环已被活化；随后,戊糖磷酸途径被活化。种子吸胀前8h为快速吸水期,传统认为快速吸水阶段属于物理吸水,而本研究则发现玉米种子在快速吸水阶段即已启动了蔗糖的转化,糖酵解和三羧酸循环途径被活化。
英文摘要:
In order to study the changes of soluble sugar and energy supply during initial maize seed germination, maize variety ‘Dabaitou’ seeds were imbibed at 25℃ for up to 24 hours. The embryo and endosperm were separated at 8h, 16h and 24h imbibition, respectively. The dynamic changes of seed water, soluble sugar, the activities and gene expression of key enzymes of glucose metabolism, and ATP content were analyzed. The results showed that in maize seed the reserved soluble sugars was mainly stored in the form of sucrose in the embryo. The sucrose content decreased gradually in imbibed seeds, meanwhile maltose, glucose and fructose content increased, and the transformation of sucrose was initiated at 8h-imbibition. The glycolytic pathway and the tricarboxylic acid cycle was activated at 8h-imbibition, and the pentose phosphate pathway was activated and played a leading role with prolonged imbibition. According to the water absorption curve, the first 8 hours was a fast water-absorbing stage (Phase I), followed by a slower absorbing stage during 8-24h (Phase II). In the previous study, Phase I was deemed as a physical imbibition stage. Remarkably, this study indicates that the mobilization and metabolism of reserved soluble sugar are initiated at Phase I.
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