High Resolution Imaging of Starch Granule Surfaces by Atomic Force Microscopy

High resolution imaging of the surfaces of starch granules from two different botanical sources has been performed using two complementary techniques: low voltage scanning electron microscopy (LVSEM) and atomic force microscopy (AFM). LVSEM provided superior images ofuncoatedgranules than possible by conventional scanning electron microscopy, and these images were used to validate the features revealed at higher resolution by AFM. The AFM images demonstrated that, although intra-sample variation exists, the surfaces of wheat and potato starch granules possess substantially different topographies. Potato starch had many protrusions (50–300 nm in diameter), above a flatter surface, which contained structures in the order of 10–50 nm. Wheat starch had far fewer protrusions and generally had a smoother surface made up of 10–50 nm structures. The 10 to 300 nm structures are believed to be carbohydrate in nature and correspond to ‘blocklet’ structures, comprising groups of amylopectin side-chain clusters presenting at the granule surface. We conclude therefore that near-molecular resolution topography of the starch granule surface has been revealed, which has allowed further insight into starch granule structure and molecular organisation.     

Cellularization of the Free Nuclear Endosperm in Rice Caryopsis Revealed by Light and Electron Microscopy

Summary

Events during the early development of rice endosperm were studied cyto-histologically. Attempts were made to clarify the sequential changes during the early developmental stages of endosperm to reveal the ultrastructural details of the first-anticlinal wall formation and the subsequent cellularization. Early development of nuclear endosperm rapidly proceeded after anthesis and a large number of free nuclei proliferated until 48 HAA. In a large central cell, phragmoplasts arose as a result of alignment of vesicles appeared between the free nuclei located in the peripheral cytoplasm layer along nucellus. The phragmoplasts initially fused with wall of the nucellus and formed the initials of anticlinal wall. The initial wall grew toward a large central vacuole and reached tonoplast of central vacuole. Thereby, alveolar typed cell compartments ensued. Furthermore, the anticlinal wall continuously arose to form a large number of alveolar typed compartments. The cellularization of compartments including a free nucleus was achieved during 48 to 72 HAA. Microtubules and Golgi apparatus seemed to contribute to cellularization. Lastly, the process forming first-anticlinal wall is followed on a representative diagram and compared with the cellularization in other cereal endosperms.     

Endosperm Structure of White-Belly and White-Core Rice Grains Shown by Scanning Electron Microscopy

Abstract:

White-belly and white-core are the major two types of grain chalkiness in japonica rice. This study aims to compare the morphological features of white-belly and white-core using a scanning electron microcope (SEM). A japonica rice cultivar Wuyujing3 and its mutants were used as materials. Nearly 1000 SEM images were observed, and 12 representative photos were selected. SEM images showed contrasting differences between white-belly and white-core in endosperm microstructure including the shape of endosperm cell, the size distribution of starch granules, and the amount of protein bodies. White-belly and white-core also varied markedly in morphological features of the cracked compound starch granules. Our findings should help to advance our understanding of the multi-faceted nature of grain chalkiness from the perspective of starch and protein accumulation, and should be of value for future work on rice grain chalkiness.     

Ultrastructural Analysis of Electrofused Protoplasts from Pansy and Wild Viola by Scanning Electron Microscopy

Summary

Ultrastructural changes during the fusion of the protoplasts isolated from wild viola callus (without chloroplasts) and pansy mesophyll cells (with chloroplasts) were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The presence of pansy protoplasts in the fusion products was proved by the presence of chloroplasts lying beneath the plasma membrane identified by SEM. Involvement of pansy chloroplasts in the fusion products was confirmed by TEM. Thus it was possible to distinguish between viola protoplasts and pansy protoplasts by SEM. During the process of protoplast fusion, adhesion of two protoplasts, the rupture and recovery of the membrane between them, and a single-paired spherical fusion body were clearly observed by SEM using our preparation method. Fused protoplasts divided and a microcolony was produced.     

A Multi-stages Biosynthetic Pathway in Starch Granules Revealed by the Ultrastructure of Maize Mutant Starches

Our previous work indicated that starches containing B-type crystallites show low susceptibility to amylolysis and suggested that B-type crystallites have an effect on starch granule organisation. To elucidate granular ultrastructure, double wxae and aedu maize mutant starches containing A- (30 and 50% respectively) and B-type (70 and 50% respectively) crystallites were treated with porcine pancreatic alpha -amylase. The surface structure of the native and degraded starches was studied by scanning electron microscopy, and the internal ultrastructure by transmission electron microscopy after staining with PATAg reagents. The results confirm the influence of B-type crystallites on granule organisation and indicate that starches containing B-type crystallites show an amylolysis attack pattern with minor exocorrosion and major endocorrosion. The granule organisation of A- and B-type starches proposed is not consistent with an onion ring model¹and may account for the different behaviour of these starches to amylolysis. Transmission electron microscopy showed that most native wxae and aedu starch granules are composed of a core with a classical alternating structure and a peripheral ring. The peripheral ring in wxae starch was ordered and resistant to amylolysis, whereas that of aedu was disordered and degradable. It is proposed that these two specific forms of granule organisation are attributable to variations in the enzymatic activities of specific starch synthesising enzymes during the course of starch biosynthesis.     

The Endosperm Morphology of Rice and its Wild Relatives as Observed by Scanning Electron Microscopy

While cultivated rice, Oryza sativa, is arguably the world’s most important cereal crop, there is little comparative morphological information available for the grain of rice wild relatives. In this study, the endosperm of 16 rice wild relatives were compared to O. sativa subspecies indica and O. sativa subspecies japonica using scanning electron microscopy. Although the aleurone, starch granules, protein bodies and endosperm cell shapes of the cultivated and non-cultivated species were similar, several differences were observed. The starch granules of some wild species had internal channels that have not been reported in cultivated rice. Oryza longiglumis, Microlaena stipoides and Potamophila parviflora, had an aleurone that was only one-cell thick in contrast to the multiple cell layers observed in the aleurone of the remaining Oryza species. The similarity of the endosperm morphology of undomesticated species with cultivated rice suggests that some wild species may have similar functional properties. Obtaining a better understanding of the wild rice species grain ultrastructure will assist in identifying potential opportunities for development of these wild species as new cultivated crops or for their inclusion in plant improvement programmes.     

小麦淀粉粒蛋白表达差异及其与淀粉糊化特性的关系

为探明小麦淀粉粒蛋白与淀粉糊化特性的关系,对河南省18个主栽小麦品种淀粉粒蛋白进行分离,并对淀粉粒蛋白类型、淀粉含量、糊化特性参数进行了研究.结果表明,18个小麦品种分离出了8种主要的淀粉粒蛋白,9种组合带谱,并以组合类型Ⅰ和组合类型Ⅶ所占比例最高,为55.56%,均表现为7条谱带.通过对淀粉粒蛋白条带数量以及谱带光密度总量和淀粉特性的相关性分析表明,淀粉粒蛋白光密度总量和直链淀粉含量、峰值黏度、低谷黏度、最终黏度呈显著负相关,表明淀粉粒蛋白表达量影响淀粉的糊化特性.同时选取6个小麦品种,分别采用盐、SDS、蛋白酶对淀粉进行处理后,淀粉峰值黏度显著提高,其中以盐处理提高幅度最大,且不同处理之间差异达显著水平.对处理后淀粉粒蛋白进行电泳分析表明,处理后的条带明显减少,说明处理后小麦淀粉粒蛋白含量下降.综合试验结果,不同小麦品种淀粉粒蛋白表达存在差异,同时淀粉粒蛋白表达量高低影响淀粉峰值黏度.     

Changes in Surface Structure during Direct Somatic Embryogenesis in Rice Scutellum Observed by Scanning Electron Microscopy

Abstract

Direct somatic embryogenesis in rice scutella was studied by scanning electron microscopy paying attention to the morphological change of surface structure. Somatic embryos were formed when the scutella of immature embryos of cv. Nipponbare were cultured on MS media containing 2 mg L^?1 2,4-D. Embryos were then transferred to the media containing 1 mg L^?1 2,4-D and germinated on hormone-free media. The developmental stages of typical monocotyledonous somatic embryo were classified into proembryo, globular, scutellar and coleoptilar stages by referring to the terminology used for zygotic embryos. Each stage had a characteristic surface structure. The surface of proembryo was smooth. Fibrillar material was observed during the transition from proembryo to globular stage. Fibrillar material was then gradually replaced by a mesh-like structure at the globular stage. With subsequent development of globular embryo, the apical scutellum region became flattened and the ridge of mesh-like structure became lower. Development of scutellum followed by the emergence of coleoptile from the scutellar notch was observed at the scutellar stage. The coleoptile surface was covered with elongating cells. The coleoptilar stage was characterized by the growth of coleoptile and the development of root. However, aberrant somatic embryos which had leafy scutellum and multiple shoot meristem, were also observed.     

我国三个野生稻种谷粒和花药形态的扫描电镜观察

为了探求栽培稻同野生稻的亲缘关系,采用扫描电镜比较观嘉了我国的普通野稻(O. rufipogon)、药用野稻(O. officinalis)、瘤粒野稻(O. meyeriana subsp. tuberculata)和栽培稻(0．sativa)的谷粒和花药的形态结构,获得下列主要结果：1)谷粒表面的形态特征——栽培稻,普通野稻和药用野稻是由排列整齐、分布均匀的乳头状突起组成,瘤粒野稻是由分布不均匀的小瘤状突起组成。栽培稻、普通野稻和药用野稻具有粗刺毛和纤细毛,瘤粒野稻具有钩毛和纤细毛。2)花药壁表面结构——栽培稻和普通野稻是由排列整齐的长形细胞组成;药用野稻和瘤粒野稻由两类细胞组成,一类是排列整齐的细胞, 另一类是大小不均、排列不呈条状的细胞。从谷粒形态、刺毛种类和分布、稃表面结构、花药形态、花药壁表面结构的相似性和差异性的研究结果表明,栽培稻与普通野稻的亲缘关系较近。     

杂交稻米及其亲本淀粉粒形态的扫描电镜观察

 用扫描电镜观察了品质级别有显著差异的3个水稻不育系和3个恢复系及其所配的9个杂交组合共15个材料的胚乳淀粉粒。结果表明：不同品质的稻米均有其固定的淀粉粒形态。杂交稻米淀粉粒的形态因双亲米质的优劣而具有明显差异。双亲优质的杂交稻米，表现优质米淀粉粒形态；优质与中质杂交，表现中亲淀粉粒形态；优质与普通品质杂交，表现为超中亲淀粉粒形态；双亲均是普通品质者，表现质量超亲淀粉粒形态；中质与普通品质杂交，趋向高亲淀粉粒形态；双亲均是中质者，表现中质米淀粉粒形态。据此，淀粉的形态特征可作为鉴定稻米品质优劣的一个重要指标，又可为杂交稻品质育种从淀粉粒形态上选择亲本提供依据。     

Effect of Sprouting on Proteins and Starch in Quinoa (Chenopodium quinoa Willd.)

Plant Foods for Human Nutrition - This study aims at understanding the relation among sprouting time (from 12 up to 72 h), changes in protein and starch components, and flour functionality...     

Effects of Rice Variety and Growth Location in Cambodia on Grain Composition and Starch Structure简

The effects of variety and growth location on grain composition and starch structures were investigated using three rice (Oryza sativa L.) cultivars (Phka Romduol, Sen Pidao and IR66) with different amylose contents. All the three cultivars were planted in three different agro-climatic zones (Phnom Penh, Coastal and Plateau) of Cambodia. The protein content of polished grains increased when rice was planted at a location with higher average temperature, but their lipid content decreased. The amylose content and degree of branching were not greatly affected by the minor temperature differences among the growing locations. Starch fine structures characterized by the chain-length distribution were significantly different among the cultivars, but not significantly among different locations. The results suggested that protein and lipid biosyntheses were more sensitive to the environmental temperature than that of starch in rice grains.     

Effects of Rice Variety and Growth Location in Cambodia on Grain Composition and Starch Structure

The effects of variety and growth location on grain composition and starch structures were investigated using three rice （Oryza sativa L.） cultivars （Phka Romduol, Sen Pidao and IR66） with different amylose contents. All the three cultivars were planted in three different agro-climatic zones （Phnom Penh, Coastal and Plateau） of Cambodia. The protein content of polished grains increased when rice was planted at a location with higher average temperature, but their lipid content decreased. The amylose content and degree of branching were not greatly affected by the minor temperature differences among the growing locations. Starch fine structures characterized by the chain-length distribution were significantly different among the cultivars, but not significantly among different locations. The results suggested that protein and lipid biosyntheses were more sensitive to the environmental temperature than that of starch in rice grains.     

四川小麦品种(系)淀粉颗粒结合蛋白多态性分析

为了解四川小麦品种(系)淀粉颗粒结合蛋白的多样性,对66份四川小麦地方品种、100份新育成品种(系)以及21份小麦骨干亲本材料的淀粉颗粒结合蛋白进行了SDS-PAGE分析。结果表明,在187份供试材料中共分离出7种蛋白条带组合类型,10种不同的蛋白条带,其中5种条带在供试材料中检测到缺失和迁移率改变。114份材料表现为SGP-1A蛋白缺失,而在所有供试的四川小麦地方品种中该蛋白均表达。共4份材料在SGP-1B位点蛋白迁移率改变,18份材料的Wx-1B蛋白条带缺失,8份材料的Wx-1D蛋白条带缺失,仅有1份材料的Wx-1A蛋白条带缺失。通过与中国春缺体-四体(N7AT7B、N7DT7B、N4AT4B)、乌拉尔图小麦(AA)、节节麦(DD)、圆锥小麦(AABB)淀粉颗粒结合蛋白的比较,并结合质谱鉴定,进一步验证了所鉴定条带的准确性。本研究表明,四川小麦新育成品种(系)和骨干亲本比四川小麦地方品种具有更丰富的淀粉颗粒结合蛋白变异类型,鉴定出的变异材料可用于淀粉颗粒结合蛋白功能的研究和小麦淀粉品质育种。     

燕麦种质资源遗传多样性的AFLP分析

为给燕麦种质资源的收集保护和育种研究提供依据,利用扩增片段长度多态性(AFLP)技术对74份燕麦种质资源的遗传多样性进行了分析。结果表明,10对AFLP引物共产生784个扩增位点,多态性位点比率达96.91%;供试燕麦种质的平均Nei′s指数为0.382,平均Shannon′s信息指数为0.573,各供试材料的AFLP多态性丰富,表现出较高的遗传多样性,利用AFLP标记评价燕麦种质的遗传多样性具有较高的检测效率。对AFLP数据进行聚类分析,构建了供试燕麦种质的UPGMA系统进化树,74份燕麦种质可以聚为五大种质群,聚类结果与地理来源及皮裸性有一定的相关性。     

基于SNP标记的糯玉米种质资源遗传多样性分析

为了提高糯玉米种质资源的利用效率,挖掘优异糯玉米种质资源、改良糯玉米品种,利用(Single nucleotide polymorphism,SNP)芯片技术对44份不同来源的糯玉米自交系和5份分别代表中国玉米5大类群的普通玉米自交系进行全基因组扫描。结果表明,34 257个SNP标记在49份玉米自交系中的多态性信息含量(polymorphism information content,PIC)为0.02～0.56,平均含量为0.32;最小等位基因频率(minor allele frequency,MAF)≥0.03。49份玉米自交系间的状态一致性(identity-by-state,IBS)变幅为0.59～0.99,平均为0.68。基于IBS利用Neighbor-joining(NJ)聚类分析方法,将49份自交系划分为5个类群,分别包含19份、9份、4份、9份和3份材料,其中系谱来源不清晰的糯玉米自交系被划分至不同类群,明确了它们的亲缘关系。     

利用SSR标记分析木薯遗传多样性

应用简单重复序列(SSR)标记对国家木薯种质资源圃195 份国内(外)品种(系)进行遗传多样性分析。结果表明：44对引物共扩增出186个等位基因,每对引物平均扩增出2～8个等位基因,平均Shannon's信息指数I为1.01,平均多态性信息量(PIC)为0.49。195个品种(系)的遗传相似系数(GS)分布在0.57～0.99。聚类分析结果表明,在遗传距离0.71处,可将供试材料分为7个类群。     

草菇菌株的ISSR遗传差异分析

为了借助分子标记手段对草菇菌株进行鉴别,利用筛选出的9个ISSR引物,对17个草菇菌株基因组DNA进行PCR扩增,对草菇菌株的ISSR遗传差异进行分析。结果显示,ISSR-PCR共扩增出81条清晰的DNA片段,其大小介于200～2 000 bp,其中多态性片段61条。DNA指纹图谱分析结果表明,所有供试草菇菌株间的DNA指纹均存在差异,各菌株间的遗传相似系数在0.63～0.95之间。聚类分析结果表明,17个草菇菌株在遗传相似系数为0.74处可分成5个组群,草菇V11、V23和V365与其它菌株的遗传距离最远。来自同一菌株的2个分离物V26-1和V26-2归在同一组内,且遗传相似系数达0.93。研究结果表明,ISSR分子标记技术可作为草菇菌株鉴别的有效辅助手段。     

早籼稻垩白形成中胚乳淀粉粒发育的电镜观察

对不同垩白度早籼品种中优早3号（少垩白）和泸红早1号（多垩白）的不同温度处理下的胚乳淀粉粒进行了扫描电镜观察,结果显示胚乳腹部淀粉粒形成的发育过程明显受温度条件的影响。在灌浆初始,高温促使淀粉粒发育进程提前,淀粉粒形状呈圆球形,边缘光滑,从而造成成熟时淀粉粒间的空隙明显,结构疏松,垩白率高。这在少垩白品种中优早3号中表现得尤为显著。