Granule Structure and Distribution of Allomorphs in C-Type High-Amylose Rice Starch Granule Modified by Antisense RNA Inhibition of Starch Branching Enzyme
Granule Structure and Distribution of Allomorphs in C-Type High-Amylose Rice Starch Granule Modified by Antisense RNA Inhibition of Starch Branching Enzyme
复制标题
反义RNA抑制淀粉分支酶修饰C型高直链淀粉颗粒的颗粒结构及异形体分布
DOI：
10.1021/jf103412d
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发表时间：
2010-11-24
影响因子：
6.1
通讯作者：
Liu, Qiaquan
中科院分区：
文献类型：
--
作者：
Wei, Cunxu;Qin, Fengling;Liu, Qiaquan
c型淀粉是a型和b型晶体淀粉的结合体，通常存在于豆科植物和根茎中。利用反义RNA抑制淀粉分支酶，开发了水稻高直链淀粉转基因品系。该TRS胚乳中的淀粉被鉴定为典型的c型结晶淀粉，但其细粒结构和异型分布尚不清楚。在本研究中，我们对该TRS淀粉在酸水解过程中进行了形态学和光谱研究，以确定A型和b型异形体的分布。通过光学显微镜、扫描电镜和透射电镜对不同时间酸水解后淀粉颗粒的形貌进行了比较。结果表明：TRS淀粉亚颗粒的中心部位存在无定形区；在酸水解过程中，淀粉由亚颗粒的内部向外表面降解，而亚颗粒的外围部分和淀粉颗粒的周围带具有很强的抗酸水解能力。x射线粉末衍射、C-13交叉极化魔角自旋核磁共振和衰减全反射傅立叶变换红外光谱变化表明，a型异构体水解速度快于b型异构体，随着水解时间的延长，x射线衍射剖面由天然的c型逐渐转变为cb型。我们的研究结果表明，在TRS淀粉中，a型异构体位于无定形区周围，b型异构体位于亚颗粒周围区域和淀粉颗粒周围带周围。因此，TRS c型淀粉颗粒中A型和b型异构体的位置与c型豆科和根茎淀粉中的位置有显著差异。
C-type starch, which is a combination of both A-type and B-type crystal starch, is usually found in legumes and rhizomes. We have developed a high-amylose transgenic line of rice (TRS) by antisense RNA inhibition of starch branching enzymes. The starch in the endosperm of this TRS was identified as typical C-type crystalline starch, but its fine granular structure and allomorph distribution remained unclear. In this study, we conducted morphological and spectroscopic studies on this TRS starch during acid hydrolysis to determine the distribution of A- and B-type allomorphs. The morphology of starch granules after various durations of acid hydrolysis was compared by optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results showed that amorphous regions were located at the center part of TRS starch subgranules. During acid hydrolysis, starch was degraded from the interior of the subgranule to the outer surface, while the peripheral part of the subgranules and the surrounding band of the starch granule were highly resistant to acid hydrolysis. The spectroscopic changes detected by X-ray powder diffraction, C-13 cross-polarization magic-angle spinning NMR, and attenuated total reflectance Fourier transform infrared showed that the A-type allomorph was hydrolyzed more rapidly than the B-type, and that the X-ray diffraction profile gradually changed from a native C-type to a CB-type with increasing hydrolysis time. Our results showed that, in TRS starch, the A-type allomorph was located around the amorphous region, and was surrounded by the B-type allomorph located in the peripheral region of the subgranules and the surrounding band of the starch granule. Thus, the positions of A- and B-type allomorphs in the TRS C-type starch granule differ markedly from those in C-type legume and rhizome starch.