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.     

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.     

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.     

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.     

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。     

斜纹夜蛾侧沟茧蜂触角感受器的扫描电镜观察

应用扫描电镜对斜纹夜蛾侧沟茧蜂（Microplitis prodeniae）的触角感受器进行观察。结果显示：触角为线形,鞭节有16亚节;触角共有6类感器,分别为毛形感器、刺形感器、锥形感器、腔锥形感器、板形感器和钟形感觉器;毛形感器最多,分布整个触角;刺形感器分布在柄节和梗节,数量较少;锥形感器、腔锥形感器、板形感器和钟形感觉器分布在鞭节,其中钟形感觉器仅着生于雄蜂鞭节;雌雄蜂触角在形状和结构上相似,但雄蜂触角的长度和直径显著大于雌蜂;雄蜂板形感器的数量、大小和密度显著高于雌蜂。     

白肋烟腺毛形态结构的环境扫描电镜观察

以白肋烟品种鄂烟一号为材料,采用环境扫描电子显微镜对其腺毛的形态结构进行了观察。结果表明,长度为63 mm幼叶Ⅰ密被腺毛,包括长柄腺毛、短柄腺毛和分枝腺毛,腺毛由1个基细胞、1至几个柄细胞和多个头细胞组成,其中长柄腺毛的个体较大且最多,短柄腺毛粗短、数量较少,分枝腺毛为1～2次分枝,个体最大、但数量很少,3种类型腺毛分别占腺毛总数的69.29%、29.68%和1.03%;至长度为192 mm幼叶Ⅱ时,腺毛的密度较幼叶Ⅰ降低了92.49%,部分个体大的长柄腺毛已呈衰老状态;到烟叶成熟时,腺毛密度较幼叶Ⅰ下降了98.01%,外观多呈明显衰老状态,腺柄皱缩或倒伏,腺头凹陷或开裂或脱落,但仍有少量腺毛正在生长发育。     

咖啡黑(枝)小蠹成虫触角感受器的扫描电镜观察

对咖啡黑(枝)小蠹(Xylosandrus compactus)雌、雄成虫触角感受器进行了扫描电镜观察。结果表明:咖啡黑(枝)小蠹雌、雄成虫之间触角形态、感受器类型和分布均无显著差异。成虫触角具有5种感受器:毛形感受器(Ⅰ、Ⅱ)、锯齿形感受器、锥形感受器、芽形感受器和刺形感受器,其中毛形感受器数量最多,占总感受器的57%,刺形感受器数量最少,仅3%。各种感受器在触角各节上的分布数量显著不同,柄节、梗节感受器数量较少,分别约占感受器总数的4%和3%;鞭节分布的感受器数量最多,约占93%,其中约85%的感受器集中分布在锤状部末端。     

人工控温条件下稻米垩白形成变化及胚乳扫描结构观察

 利用人工气候箱设高温（33℃）和适温（23℃）2个不同的温度处理,对2个不同垩白类型品种西农8116和广二矮104抽穗后稻米垩白的变化动态进行了研究,并通过对不同温度下稻米胚乳内部淀粉体形态、大小、发育程度、排列结构的扫描电镜观察,分析了稻米垩白形成变化与胚乳内部淀粉体结构特征的关系,结果表明,水稻灌浆结实期稻米垩白形成的变化过程主要是在抽穗5 d到15~20 d的这一时期,其余时段垩白度的变化幅度不大;高温（33℃）与适温（23℃）处理相比,以抽穗后10~20 d间的变化差别最为明显;胚乳淀粉体表现为“裸露型”还是“非裸露型”,主要与胚乳细胞内部淀粉粒发育程度有关,而与品种本身的垩白类型特征无必然联系     

中国野生大豆和它的近缘的收集、保存和利用

野生作物近缘的保存是一个世界范围的重要的课题,野生的作物近缘拥有更多的遗传多样性对于育成高产、抗病和具有优良品质的作物品种意义重大.文章主要介绍了中国野生大豆及它的近缘的收集保存和利用情况,在过去的40多年中,中国先后进行了3次野生大豆种质资源收集工作,共收集资源8 518份,进行的时间分别为:第一次1978-1982年,第二次1996-2000年,第三次2001年-2010年.这些种质资源采用双轨制进行保存,分别保存在北京的国家基因库和中国的西部干燥区域.同时介绍了中国科研单位对野生大豆品种资源调查研究和利用的情况.     

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。     

玉米及其野生近缘材料的分类

根据大刍草形态学性状的显著区别,大刍草可分为5个植物学种。大刍草是玉米亲缘关系最近的野生近缘材料已被众多研究结果证实,玉米的直接祖先是否是大刍草还没有定论。对玉米与大刍草的分类系统作了介绍,同时对5个大刍草植物学种的特征特性、玉米与摩擦禾分类作了描述。     

不同透明度水稻籽粒横断面扫描电镜分析

【目的】探索单淀粉粒断面观察方法,并阐明稻米透明度与直链淀粉含量的关系以及造成稻米透明度下降的淀粉结构基础。【方法】采用扫描电镜对经过不同处理的具有不同透明度的籼稻和粳稻胚乳横断面进行淀粉粒结构观察研究。【结果】籼稻和粳稻稻米的透明度在直链淀粉含量低于15%的软米中明显下降。通过比较不同籽粒横断面断开方式,发现直接机械断裂法无法断开单个淀粉粒,机械断裂加玻璃刀刮刻法可以断开单个淀粉粒但断面结构变形且无法定量分析。液氮脆断法可以观察到单个断裂的淀粉粒以及其中的空腔。比较籼稻和粳稻胚乳横断面淀粉粒的排列方式和单个淀粉粒内部结构,表明所有品种稻米胚乳淀粉粒均规则且紧凑排列,但所有暗胚乳稻米籽粒横断面中淀粉粒内部存在明显的空腔且糯稻淀粉粒空腔的数目和大小均明显高于暗胚乳稻米。进一步通过梯度烘干实验,证明稻米淀粉粒中的空腔数目和大小随着水分的降低而增多和变大。【结论】液氮直接脆断法是观察水稻单个淀粉粒断面的有效方法。稻米透明度与胚乳淀粉粒的排列紧密程度无关而与稻米的含水量以及单个淀粉粒中间的气腔数目和大小直接相关。此外,直链淀粉含量越低,淀粉粒中间的空腔数目越多,孔径越大。     

不同透明度水稻籽粒横断面扫描电镜分析

摘 要：【目的】探索单淀粉粒断面观察方法,并阐明稻米透明度与直链淀粉含量的关系以及造成稻米透明度下降的淀粉结构基础。【方法】采用扫描电镜对经过不同处理的具有不同透明度的籼稻和粳稻胚乳横断面进行淀粉粒结构观察研究。【结果】籼稻和粳稻稻米的透明度在直链淀粉含量低于15%的软米中明显下降。通过比较不同籽粒横断面断开方式,发现直接机械断裂法无法断开单个淀粉粒,机械断裂加玻璃刀刮刻法可以断开单个淀粉粒但断面结构变形且无法定量分析。液氮脆断法可以观察到单个断裂的淀粉粒以及其中的空腔。比较籼稻和粳稻胚乳横断面淀粉粒的排列方式和单个淀粉粒内部结构,表明所有品种稻米胚乳淀粉粒均规则且紧凑排列,但所有暗胚乳稻米籽粒横断面中淀粉粒内部存在明显的空腔且糯稻淀粉粒空腔的数目和大小均明显高于暗胚乳稻米。进一步通过梯度烘干实验,证明稻米淀粉粒中的空腔数目和大小随着水分的降低而增多和变大。【结论】液氮直接脆断法是观察水稻单个淀粉粒断面的有效方法。稻米透明度与胚乳淀粉粒的排列紧密程度无关而与稻米的含水量以及单个淀粉粒中间的气腔数目和大小直接相关。此外,直链淀粉含量越低,淀粉粒中间的空腔数目越多,孔径越大。     

利用野生稻选育水稻恢复系研究

为了利用野生稻优良基因选育强优势的水稻恢复系,从野生稻资源中筛选出抗性强、具有较好农艺性状且恢复能力强的野生稻,与传统优良恢复系远缘杂交,后代适当复交,采用“大群体、多世代”的系谱法处理杂交后代。经过17 a（1980—1997）的选育,获得了测25、测253、测258、测1012等4个优良恢复系。至2006年,用这些恢复系配组育成的14个杂交稻组合通过了省级以上品种审定,累计推广面积达693.3万hm^2。     

同源四倍体水稻胚乳发育:极核融合和胚乳细胞化

利用激光扫描共聚焦显微术和塑料包埋半薄切片技术观察同源四倍体水稻极核融合及游离核进一步发育的过程,发现同源四倍体水稻约有1/3子房极核融合过程和游离核进一步发育与其二倍体原种的基本一致;2/3子房出现各种异常现象,如极核未受精、受精异常和胚乳游离核发育滞后等。应用荧光增白剂染色对胚乳细胞化过程进行观察,直接观察到胚乳初生壁的出现和形成过程以及不同部位的胚乳细胞壁的形成机理。表明同源四倍体水稻与二倍体水稻胚乳的细胞化过程基本一致,胚乳细胞初始垂周壁来源于珠孔端胚囊壁内突向心游离生长,初始平周壁来源于游离核有丝分裂产生的成膜体,而中间胚乳细胞壁则有些来源于游离核有丝分裂产生的成膜体,有些是自由生长而来。同源四倍体水稻胚乳细胞化过程也出现相当比例的异常现象,如无细胞壁形成、细胞化不同步和产生分枝状的细胞壁等。同源四倍体水稻胚乳发育过程中出现的极核融合、游离核发育和细胞化过程等异常都可能导致同源四倍体水稻的结实率降低。     

秋水仙素处理后水稻种子内胚乳蛋白的差异性比较分析

经过秋水仙素对二倍体水稻品种圭630（2）处理后,其后代材料在蛋白质水平上表现出明显的差异性。染色体组的倍性水平对水稻种子内胚乳蛋白的表达量有明显的影响。经过秋水仙素处理后,在具有嵌合性特征的植株上大粒种子与原始亲本的种子在总蛋白含量上存在着明显的差异,大粒种子与小粒种子的差异也很明显。染色体组的多倍化对原始亲本的胚乳蛋白含量有明显的影响,由此所获得的同源四倍体水稻株系,其种子内的蛋白质含量比较多。SDS—PAGE分析结果表明,经过秋水仙素诱导后,试验材料的种子内蛋白质亚基的类型没有出现新的变异,而蛋白质亚基的表达量发生了明显的变化。     

Location of Starch Granule-associated Proteins Revealed by Confocal Laser Scanning Microscopy

Distinct locations of starch granule-associated proteins were revealed using a protein-specific dye with confocal laser scanning microscopy (CLSM). The dye, 3-(4-carboxybenzoyl) quinoline-2-carboxaldehyde, fluoresces only after it reacts with primary amines in proteins, thereby removing background interference from residual dye. CLSM has the capability to discern fluorescence-labelled protein distribution in an optical slice of an intact starch granule while it is still in an intact state. With these techniques, starch granule proteins were revealed to be concentrated in internal concentric spheres in potato, maize, and wheat starches. Spheres were more distinct in potato starch than in other starches. Amylose-free potato and waxy maize starches showed no protein spheres, indicating that the internal protein spheres are composed of granule-bound starch synthase (GBSS). Identification of GBSS suggests the location of biosynthesis of amylose in starch granules, as well as spatial and temporal aspects of biosynthesis.     

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。     

甘薯近缘种Ipomoea cordatotriloba基因组大小测定及高通量调查测序

利用流式细胞术,以大豆Williams 82为内参,对甘薯近缘野生种Ipomoea cordatotriloba进行基因组大小测定,结合染色体压片技术进行倍性鉴定,并利用二代高通量测序技术对测定结果进行验证。结果表明:利用流式细胞术测得I. cordatotriloba基因组大小为(539.69±13.76)Mb;染色体压片结果显示其染色体数目为30条,由于其基数x=15,从而获知I. cordatotriloba为二倍体;经K-mer计算并修正后得出的C值为560.70 Mb,与流式细胞分析结果相近;同时,测序结果显示其基因组杂合率为0.40%;重复序列比率为57.93%;GC含量为38.10%。以上结果为此物种全基因组精细图谱绘制打下基础,同时为甘薯近缘野生种的利用提供参考。