Ca在水稻籽粒中的富集及其与其它7种元素的关系

通过环境扫描电镜结合X射线电子探针显微分析技术,对21种不同基因型的水稻籽粒颖壳内、外表面以及颖果表面、糊粉层、近糊粉层和米中部的Ca含量进行测定。结果表明,Ca元素在水稻籽粒不同部位的含量有明显差异,颖壳内外表面和颖果表面Ca含量较高,近糊粉层和颖果中部含量较低,在颖果中Ca主要富集在糊粉层中;而且不同基因型水稻籽粒同一部位或不同部位Ca的积累量也有较大差异,这可能是由遗传差异引起的。糊粉层中的Ca含量影响着颖壳外表面、颖果表面、近糊粉层和米中部的Ca含量。另外,籽粒不同部位Ca含量与P、Mg、K、Si、Al、Cd含量之间存在显著或极显著的非线性关系,与Pb含量之间不存在显著的非线性关系。说明Ca在水稻籽粒中富集的同时也影响着P、Mg、K、Si、M、Cd等元素的富集。     

Si在燕麦籽粒中的富集及其与其它8种元素的关系

通过环境扫描电镜结合X射线电子探针显微分析技术,对22个基因型的燕麦籽粒皮层、糊粉层、近糊粉层和颖果中部的Si含量进行测定.结果表明,Si元素在燕麦籽粒不同部位的含量有明显差异,皮层和糊粉层Si含量较高,近糊粉层和颖果中部含量较低,在颖果中Si主要富集在糊粉层中;而且不同基因型燕麦籽粒同一部位或不同部位Si的积累量也有较大差异,这可能是由遗传差异引起的.糊粉层中的Si含量影响着近糊粉层和颖果中部的Si含量.另外,籽粒不同部位Si含量与P、Ca、Mg、S、Al、Pb含量之间存在显著或极显著的非线性关系,颖果中部的Si含量与K、Cd含量之间不存在显著的非线性关系.说明Si在燕麦籽粒中富集的同时也影响着P、Ca、Mg、S、Al、Pb等元素的富集.     

利用原子吸收光谱法和电镜能谱仪法分析重金属Pb、Cd在水稻颖果不同部位中的分配

比较研究了传统原子吸收光谱法与电镜能谱仪法分析重金属Pb、Cd在水稻籽粒不同部位中的分配情况,研究结果表明:两种方法均显示,Pb、Cd在水稻颖果中的分配为胚>糊粉层>果皮>近糊粉层处胚乳>颖果中心,其中,胚、糊粉层和果皮Pb、Cd含量差异较小,整个胚乳Pb、Cd含量变化也不大,但胚、糊粉层和果皮Pb、Cd含量显著高于胚乳.扫描能谱仪能够准确反映重金属在植物不同部位分布的差异,结果与原子吸收光谱法无显著差异.扫描能谱仪法的优点在于操作方便快捷,但是只能用于定性,不能定量测定出某一部位重金属的准确含量,因此,不能代替传统的原子吸收光谱法.     

Cd、Pb和As在不同品种水稻籽粒中的富集特征研究

为研究不同品系水稻籽粒对Cd、Pb和As吸收累积的差异,于2014年采集了粤北矿区周边农区的316份水稻样品。研究结果表明:常规稻稻米中Cd、Pb和As含量平均值分别为:0.290 mg/kg、0.060 mg/kg和0.144 mg/kg,杂交稻稻米中Cd、Pb、As含量分别为:0.237 mg/kg、0.044 mg/kg和0.132 mg/kg,常规稻重金属含量整体均高于杂交稻。稻壳向大米中的转移能力为CdAsPb。银占、美香占和深两优等品系水稻为Cd污染敏感富集型品系,深优为Cd、Pb耐性低累积品系。常规稻稻米中Cd和As的吸收呈拮抗作用,杂交稻稻米中Cd和Pb的吸收呈协同作用。因此,根据不同基因型水稻对重金属累积的差异性,筛选出重金属低累积水稻品种的方法是可行的。     

转基因cry1Ab在高粱不同器官中的表达水平

用Cry1Ab/Cry1Ac板式试剂盒测定了Cry1Ab蛋白在转基因高粱不同器官中的表达水平。结果表明,不同组织器官的Cry1Ab蛋白含量有明显差异,其顺序为叶鞘>叶>颖壳>籽粒>根>茎髓,在花药中则检测不到;不同部位的叶片、叶鞘和茎髓的Cry1Ab蛋白含量也有较大差异,中部叶的Cry1Ab蛋白含量高于上部叶和基部叶,叶鞘中是中部>基部>上部,茎髓中则表现为基部最高。     

水稻不同品种对铅吸收、分配的差异及机理

为探究水稻不同品种对Pb吸收积累的差异及机理,以20个不同基因型水稻品种(系)为材料,采用盆栽方法,研究了Pb在水稻植株各器官中的分配及在籽粒中的分布．结果表明,不同品种间,Pb积累量存在显著差异,但品种间的这种差异与品种类型关系不明显;不同器官、不同生育时期,Pb积累量和积累速率不同;各器官Pb浓度按根、茎、叶、穗、籽粒的顺序大幅度下降,分配到籽粒中的Pb比例很低;根与茎,茎与叶片、穗(抽穗期)、籽粒Pb含量呈极显著负相关;根与叶、穗(抽穗期)、籽粒,叶与穗(抽穗期)、籽粒的Pb含量呈正相关,相关性大多达极显著或显著水平;不同品种抽穗期叶片与成熟期籽粒间的Pb含量达显著正相关;Pb在稻米加工各产物中的分布很不均匀,稻谷经脱壳及精加工1次(2min)后,精米Pb含量仅为籽粒总含Pb量的32．88％．     

导入反义蜡质基因改良水稻稻米的食味品质和营养品质

经PCR、Southern blot和稻米GUS检测,蜡质基因反义片段与gus构成的融合基因已整合到8株水稻基因组中,并能正确表达。通过稻米GUS染色追踪分析获得转反义蜡质基因纯合后代。将转基因植株的稻米送农业部稻米及制品质量监督检验测试中心进行糙米蛋白质含量和直链淀粉含量测定。结果显示：（1）在转反义蜡质基因纯合的超2-10粳稻后代中,大多数单株糙米在直链淀粉含量降低的同时,蛋白质含量有不同程度提高,糙米蛋白质含量和直链淀粉含量呈显著负相关关系;（2）对照糙米直链淀粉平均含量和糙米蛋白质平均含量分别为13.4%和9.5%。在转基因植株中,稻米直链淀粉含量最低的为11.4%,而蛋白质含量也相对最高,为13.5%。本试验结果表明在水稻中导入反义蜡质基因不仅能够降低水稻稻米的直链淀粉含量,还有可能提高水稻稻米的蛋白质含量。     

臭氧胁迫对稻穗不同部位糙米直链淀粉含量和RVA谱特征值的影响

近地层臭氧浓度升高使水稻产量下降,但臭氧胁迫对稻米品质的影响及其强弱势粒差异尚不清楚.本研究以8个不同类型水稻品种为供试材料,利用自然光气体熏蒸平台,设置对照(9 nL·L^-1)和高浓度臭氧(约100 nL·L^-1)处理,研究臭氧胁迫对稻穗不同部位糙米直链淀粉含量和RVA谱特征值的影响.结果表明: 与对照相比,臭氧处理使糙米直链淀粉含量、最高粘度、热浆粘度、崩解值和冷胶粘度分别下降5.9%、7.6%、5.9%、11.6%、2.9%,消减值和糊化温度分别增加24.9%和1.0%,均达显著水平.稻米直链淀粉含量和所有RVA特征参数的品种间差异均达极显著水平.稻穗不同部位稻米直链淀粉含量、最高粘度、热浆粘度、崩解值、冷胶粘度从大到小依次为强势粒>中势粒>弱势粒,消减值则表现相反.绝大多数情形下,臭氧与年度或臭氧与品种间的互作对稻米直链淀粉含量和RVA谱的影响达显著水平;尽管稻米RVA特征值对臭氧胁迫的响应多表现为稻穗上部略小于中部和下部,但臭氧与部位间的互作均未达显著水平.表明中等强度的臭氧胁迫使水稻食味品质明显变劣,变劣的程度因生长季和供试品种而异,籽粒着生位置受臭氧胁迫的影响较弱.     

水稻地方品种铁含量的差异评价

以来自我国12个省的113份水稻地方品种为试验材料,分析了不同省份、不同类型、不同品种糙米铁含量的差异.结果表明,113份水稻地方品种的铁含量变异范围为8.1～19.9mg/kg,平均值为11.5mg/kg,变异系数为15.56%.各省份水稻地方品种的平均铁含量大小顺序为吉林>江西>福建>广东>安徽>四川>云南>广西>江苏>湖北>湖南>贵州.粳米的铁含量显著高于籼米;糯米的铁含量显著高于粘米;紫米的铁含量显著高于普通米和红米.福建省的陆种糯和吉林省的红毛稻铁含量较高,分别为19.9mg/kg和16.5mg/kg.今后应重视吉林省地方品种以及粳稻、糯稻和紫稻地方品种的铁含量分析,积极发掘富铁水稻种质,以提供利用于水稻育种研究.     

籼稻稻米蛋白质含量与外观品质性状间不同遗传体系的条件遗传相关分析

选用稻米蛋白质含量等品质差异较大的7个籼型不育系(A)及相应的保持系(B)与5个籼型恢复系(R)杂交,组成7×5不完全双列杂交组合。应用包括胚乳、细胞质和母体植株基因的遗传主效应以及基因型×环境互作效应的数量性状遗传模型及非条件和条件分析方法,研究了籼稻稻米蛋白质含量与外观品质性状间的遗传相关性,进一步揭示了籼稻糙米重、稻米直链淀粉含量对稻米蛋白质含量与外观品质性状间遗传相关性的影响。非条件分析的结果表明,除了与糙米厚的相关性未达到显著水平以外,蛋白质含量与其它稻米外观品质性状间的遗传相关性均达极显著水平,其中与糙米宽间的相关性表现为正值,其余为负向相关。条件分析的结果显示,糙米重和直链淀粉含量对稻米蛋白质含量与外观品质性状间的遗传相关性均可产生较大的影响。糙米重主要通过基因型×环境互作效应影响蛋白质含量与外观品质性状间的遗传相关性,其中对蛋白质含量与糙米长、糙米宽、糙米厚间遗传相关性的影响主要表现为负向作用,而对蛋白质含量与糙米长宽比、糙米长厚比间遗传相关性的影响则表现为正向作用。稻米直链淀粉主要通过细胞质遗传主效应和母体加性效应影响蛋白质含量与糙米长、糙米长宽比、糙米长厚比间的遗传相关性,而对蛋白质含量与糙米宽间的相关性影响主要表现为负向作用。     

Microscopic Observation on the Development of Puccinia striiformis in the Spike and Stem of Wheat

The majority of germ tubes of the pathotype CYR32 of Puccinia striiformis f.sp. tritici formed on the surface of spike organs of the susceptible wheat cv. Suwon 11 penetrated through the stomatal pore, only a few germ tubes formed small appressoria over the stomata. In the lemma, palea and glume, the stripe rust fungus spread between the parenchyma cells close to the inner epidermal layer, but the fungus did not develop between the thick‐walled cells near the outer epidermal layer of these organs. In the awn and stem, spread of the stripe rust was confined to the intercellular spaces of the chlorophyll parenchyma, beneath the invaded stomatal pore of the epidermis and the urediniospores to be released disrupted the epidermis. In the caryopsis, the spread of hyphae was restricted to the intercellular spaces of the pericarp cells.     

糖蜜草（Melinis minutiflora Beauv．）幼穗分化发育．及花和果实形态的研究

本文对糖密草（ＭｅｌｉｎｉｓｍｉｎｕｔｉｆｌｏｒａＢｅａｕｖ．）的幼穗分化发育及花和果实的形态作了研究,将幼穗分化发育过程划分为以下九个时期：第一苞原基形成期;第一次枝梗原基形成期;第二、三次枝梗原基形成期;小穗及颖花原基形成期;雌、雄蕊原基形成期;花粉母细胞形成期;花粉母细胞减数分裂期;花粉充实期;花粉成熟期。全过程历时约需４２ｄ．从抽穗到颖果成熟约需５０ｄ。糖蜜草的花序为圆锥花序。每花序有可育花２０００—３０００朵．小穗是由小穗轴、内外颖片、不育花外稃和小花构成。小花包括有内外稃各一片、一鳞被、雄蕊三枚和一枚雌蕊,颖果千粒重为９１ｍｇ。     

ULTRASTRUCTURE OF THE MATURE UNGERMINATED RICE (ORYZA SATIVA) CARYOPSIS. THE CARYOPSIS COAT AND THE ALEURONE CELLS

The results of a light and electron microscopic study of the caryopsis coat and aleurone cells in ungerminated, unimbibed rice (Oryza sativa) caryopses are presented. Surrounding the rice grain is the caryopsis coat composed of the pericarp, seed coat and nucellar layers. The outermost layer, the pericarp, consists of crushed cells and is about 10 μm thick. The seed coat, interior to the pericarp, is one cell thick and has a thick cuticle. Between the seed coat cuticle and endosperm are the remains of the nucellus. The nucellus is about 2.5 μm thick and has a thick cuticle adjacent to the seed coat cuticle. Interior to the caryopsis coat is the aleurone layer of the endosperm. The aleurone completely surrounds the rice grain and is composed of two cell types—aleurone cells that surround the starchy endosperm and modified aleurone cells that surround the germ. The aleurone cells of the starchy endosperm contain many aleurone grains and lipid bodies around a centrally located nucleus. The modified aleurone cells lack aleurone grains, have fewer lipid bodies than the other aleurone cells, and contain filament bundles (fibrils). Plastids of aleurone cells exhibit a unique morphology in which the outer membranes invaginate to form tubules and vesicles within the plastid. Transfer aleurone cells are not observed in the mature rice caryopsis.     

TRANSFER CELLS IN THE PLACENTAL PAD AND CARYOPSIS COAT OF PAPPOPHORUM SUBBULBOSUM ARECH. (POACEAE)

During caryopsis development the layers of the pericarp, integuments, and nucellus all contribute to the formation of the caryopsis coat. The coat consists of a layer of outer pericarp epidermal transfer cells, a collapsed and senescent layer of middle pericarp cells, and a discontinuous layer of inner pericarp epidermal transfer cells. The latter is not present across the placental pad. The integuments are present as a collapsed dense layer, the nucellus is discontinuous and cellular. The placental pad occurs at the ventral surface of the caryopsis, opposite the scutellum and coleorhiza. It consists of 15–20 collapsed cell layers, including the pigment strand and placental vascular bundle. From the inside several partially collapsed cell layers of the nucellar projection occur which contain transfer-cell walls. The middle dense layers, the pigment strand, consist of the middle pericarp remnant, plus the remains of the placental vascular bundle. The pericarp inner epidermis does not extend across the pad. The aleurone layer is a continuous uniseriate layer around the entire caryopsis except at the placental pad; here it is crushed and contains the remnant of a transfer-cell wall. The outer pericarp epidermis is a continuous layer of transfer cells across the pad. These cells contain membranous inclusions suggesting that they may be functional during germination.     

Rice caryopsis development I: Dynamic changes in different cell layers

Rice caryopsis as one of the most important food sources for humans has a complex structure that is composed of maternal tissues including the pericarp and testa and filial tissues including the endosperm and embryo. Although rice caryopsis studies have been conducted previously, a systematic characterization throughout the entire developmental process is still lacking. In this study, detailed morphological examinations of caryopses were made during the entire 30‐day developmental process. We observed some rapid changes in cell differentiation events and cataloged how cellular degeneration processes occurred in maternal tissues. The differentiations of tube cells and cross cells were achieved by 9 days after pollination (DAP). In the testa, the outer integument was degenerated by 3 DAP, while the outer layer of the inner integument degenerated by 7 DAP. In the nucellus, all tissues with the exception of the nucellar projection and the nucellar epidermis degenerated in the first 5 DAP. By 21 DAP, all maternal tissues, including vascular bundles, the nucellar projection and the nucellar epidermal cells were degenerated. In summary, this study provides a complete atlas of the dynamic changes in cell differentiation and degeneration for individual maternal cell layers of rice caryopsis.     

Rice caryopsis development Ⅰ: Dynamic changes in different cell layers

Rice caryopsis as one of the most important food sources for humans has a complex structure that is composed of maternal tissues including the pericarp and testa and filial tissues including the endosperm and embryo. Although rice caryopsis studies have been conducted previously, a systematic characterization throughout the entire developmental process is still lacking. In this study, detailed morphological examinations of caryopses were made during the entire 30-day developmental process. We observed some rapid changes in cell differentiation events and cataloged how cellular degeneration processes occurred in maternal tissues. The differentiations of tube cells and cross cells were achieved by 9 days after pollination(DAP). In the testa, the outer integument was degenerated by 3 DAP, while the outer layer of the inner integument degenerated by 7 DAP. In the nucellus, all tissues with the exception of the nucellar projection and the nucellar epidermis degenerated in the first 5 DAP. By 21 DAP, all maternal tissues, including vascular bundles, the nucellar projection and the nucellar epidermal cells were degenerated. In summary, this study provides a complete atlas of the dynamic changes in cell differentiation and degeneration for individual maternal cell layers of rice caryopsis.     

Cultivar differences in soluble sugar content of mature rice grain

Mature grain from 31 rice ( Oryza sativa L.) cultivars grown in the same location was analyzed for soluble sugar content to determine quantitative differences in this parameter. Cultivar variation in caryopsis sucrose content was 4-fold ranging from 15 to 59 μmol sucrose (g fresh weight)⁻¹. Soluble reducing sugar ranged from 7 to 15 μmol hexose (g fresh weight)⁻¹. Soluble sugar content was much greater in the outer part of the grain than in the endosperm. Caryopsis enzyme activities were measured in 8 cultivars having a range of grain sucrose content. No relationship between grain sucrose content of these cultivars and the level of enzymes of sucrose metabolism, glycolysis, and oxidative pentose pathway was established. Caryopsis respiration after 1 h of imbibition also was not related to the amount of soluble sugars available in the grain among these 8 cultivars. The results show that there are significant differences in the sugar-accumulating capacity of the caryopsis of different rice cultivars. The detection of a fructose 2,6-bisphosphate-sensitive, PP_i: fructose 6-phosphate phosphototransferase (EC 2.7.1.90) in the endosperm suggests the presence of a regulatory mechanism for sucrose/starch partitioning established in other plant tissues.