National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.
Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Shanghai Chenshan Botanical Garden, 3888 Chenhua Road, Shanghai 201602, China.
Carbohydr Polym. 2015 May 20;122:417-27. doi: 10.1016/j.carbpol.2014.11.003. Epub 2014 Nov 13.
The intrinsic relationship between amylose content and starch physicochemical properties was studied using six representative starch samples (amylose content 0-65%) produced from transgenic sweet potato (cultivar Xushu22). The transgenic lines (waxy and high-amylose) and wild-type (WT) sweet potatoes were analyzed for amylose content, particle size and chain length distribution, X-ray diffraction analysis, thermal characteristics, pasting and rheological property. Compared to the WT starch, the waxy and high-amylose starches showed larger average granule sizes and had fewer short chains and more medium and long chains. X-ray diffractogram analysis revealed that high-amylose starches show a type-B crystal form with a markedly decreased degree of crystallinity in contrast to the type-A crystal form of the WT and waxy starches. In the high-amylose sweet potato starches, the rise of setback value and the reduction of breakdown value led to the high shear resistance as indicated by the higher G', G", and tanδ from the oscillation test. ΔH was not found to be decreased with the reduction of crystallinity. The shear stress resistance of starch gel after gelatinization was also enhanced as amylose content increased. Principal component analysis also confirmed that the amylose content greatly influenced the starch structure and properties, e.g., storage modulus, setback value, and average chain length. Thus, our study not only shed light on how amylose content affects starch properties but also identified novel starches that are available for various applications.
利用从转基因甘薯（品种 Xushu22）中获得的 6 种具有代表性的淀粉样品（直链淀粉含量 0-65%），研究了直链淀粉含量与淀粉理化性质之间的内在关系。对转基因（蜡质和高直链淀粉）和野生型（WT）甘薯进行了直链淀粉含量、颗粒大小和链长分布、X 射线衍射分析、热特性、糊化和流变特性分析。与 WT 淀粉相比，蜡质和高直链淀粉淀粉的平均颗粒粒径较大，短链较少，中长链较多。X 射线衍射图分析表明，高直链淀粉淀粉呈现出 B 型晶体形态，与 WT 和蜡质淀粉的 A 型晶体形态相比，结晶度明显降低。在高直链淀粉甘薯淀粉中，回生值的升高和破裂值的降低导致了较高的剪切阻力，这可以从振荡测试中较高的 G'、G"和 tanδ 值看出。ΔH 并没有随着结晶度的降低而降低。淀粉凝胶在胶凝后抵抗剪切应力的能力也随着直链淀粉含量的增加而增强。主成分分析也证实，直链淀粉含量对淀粉结构和性能有很大影响，如储能模量、回生值和平均链长。因此，我们的研究不仅阐明了直链淀粉含量如何影响淀粉性质，还鉴定了可用于各种应用的新型淀粉。
