罗汉果胚,胚乳及胚乳有器的发育

本文采用石蜡切片与酶解分离法对罗汉果Ｓｉｒａｉｔｉａ ｇｒｏｓｖｅｎｏｒｉ胚、胚乳及胚乳吸器发育过程进行观察。ａ）罗汉果胚的发育是按Ｇｅｕｍ ｕｒｂａｎｕｍ的分裂程序进行的,属紫菀型。但在合子分裂成球胚过程中,胚芽原细胞分化明显,故属紫菀型的变异型。ｂ）胚乳发育属核型,在球形胚阶段,在合点端和珠孔端有发育的胚乳吸器形成并进行旺盛生长,最大长度达１４２０μｍ,心形胚期,吸器活动开始减退,合点端核型胚     

谷子胚和胚乳的发育

合子的第一次分裂为斜的横分裂,胚发育至棒状原胚后,胚顶端一侧的细胞加速分裂形成一团分生组织细胞,由这团分生组织分化盾片、胚芽鞘、胚芽生长点和胚根。胚体的其它部分参与部分盾片和胚根鞘的构成。胚柄不参与胚的组成,胚无外胚叶,胚胎发育属禾本型。核型胚乳。从胚囊壁产生的自由生长壁把胚乳游离核隔开形成一层胚乳细胞。然后这层细胞平周分裂使胚乳细胞变成二层,以后的胚乳细胞增殖以细胞有丝分裂方式进行。胚乳的最外层     

何首乌胚和胚乳的发育

何首乌为直生胚珠,双珠被。胚发育属于柳叶菜型。心形胚柄最为发达,鱼雷形胚期胚柄奶化。早期胚胎发育营养的主要来源可能是合了中积累的淀粉和胚柄吸收来的营养。成熟胚中积累了大量的蛋白质和淀粉粒。胚乳发育属核型。从球形胚期起,胚乳细胞化过程由珠孔端向合点端逐渐推进。初始垂周壁源于姊妹核间的细胞反或非姊妹核间由次生成膜生的细胞板。初始平周壁源于有丝分裂所产生的细胞板。心形胚期,除合点端保持游离核胚乳吸器外,     

西瓜胚和胚乳的发育

应用显微技术对西瓜胚和胚乳的发育过程进行了观察并分析了西瓜胚珠败育的原因。西瓜胚发育属紫菀型。合子第一次分裂为不均等分裂 ,形成的基细胞体积明显较顶细胞大 ,两细胞均含有多个液泡。原胚发育过程中没有明显的胚柄。最外层的原胚细胞 ,与胚乳细胞相邻的壁上被胼胝质物质包围 ,且无外连丝存在 ;与胚囊壁相接的壁上无壁内突结构。胚的子叶体积增长的同时 ,子叶细胞内积累蛋白质和脂类物质 ,多糖物质的含量下降。胚乳发育属核型 ,在球形胚期开始自珠孔端向合点端细胞化 ,胚子叶分化出后开始自珠孔端向合点端退化。胚乳合点端在球形胚早期形成发达的胚乳吸器 ,开始呈游离核状态 ,后细胞化 ,在心型胚期之后退化。     

葡萄胚珠,胚乳及胚的发育

本文研究了“早玫瑰”和“新玫瑰”葡萄胚珠、胚乳和胚的发育。结果表明:花后3天胚珠即开始迅速生长,其生长的最终大小依品种成熟期的不同而各异。胚乳游离核在花后33天成为细胞状态。受精后16—21天,合子才开始第一次分裂。当胚乳充满珠心组织时,胚开始迅速发育并一直持续到果实成熟.胚的发育与果实的发育无明显竞争关系。     

花椒球心胚及胚乳的发生和发育

对花椒珠心胚及胚乳的发生和发育过程进行了详细的细胞学及细胞学研究。主要研究结果如下;珠心胚发生前,有性胚囊发育过程中从大孢子发生到胚囊形成的各个阶段均可发生退化,退化频率５０％,未退化的胚囊发育成熟,成熟胚囊仅含卵器和两个极核。卵器最终退化,极核不经受精自发形成胚肥。当胚乳游离核达到１５或３２个时,最早的珠心胚原始细胞由靠近胚囊球孔端的珠心细胞分化形成。随着子房生长,多个原始细胞持续不断地从珠孔端     

柽柳胚和胚乳发育的观察

利用常规石蜡制片技术,对柽柳（Tamarix chinensis Lour.）胚和胚乳的发育过程进行了观察。结果表明,胚发育属茄型,其基细胞先行纵裂。胚柄基部发育迅速,具吸器作用,球形胚期胚柄最为发达,其细胞质丰富,贮藏淀粉类物质,至晚心形胚期胚柄依然存在。助细胞被受精产生多胚现象。胚乳发育属核型,初生胚乳核常常晚于合子分裂,胚乳核的分裂速度慢于胚体细胞的分裂速度。当胚乳游离核为 32个时,以自由生长细胞壁的方式进行胚乳细胞化。胚乳细胞进一步增殖极少。珠心细胞只有两层,细胞核大,胞质丰富,内含贮藏物质,至心形胚期逐渐解体。     

短柄五加胚和胚乳发育的研究

短柄五加胚发育属茄型,棒形胚后期胚柄最为发达,球形胚胚柄开始退化,心形胚期胚柄解体。胚乳发育属核型,当胚乳游离核为２００￣３００个时,以自由生长细胞壁的方式进行胚乳细胞化。胚乳细胞进一步增殖以有丝分裂方式进行,球形胚时,胚乳细胞最外层细胞特化为分泌层,胚乳细胞贮藏蛋白质和脂类物质。在胚乳游离核为３２￣６４个时,单珠被的内表皮层分化为珠被绒毡层。合子分裂后,珠被绒毡层发育最为充分;棒形胚后期,珠被绒     

华山新麦草胚和胚乳的发育研究

采用常规石蜡切片法,观察了华山新麦草胚和胚乳的发育过程,结果表明,华山新麦草胚和胚乳的发育过程与一般禾本科植物基本相同,胚胎发生属紫宛型,顶细胞和基都参与胚体的形成,胚胎发育经过二细胞原胚,多细胞原胚,球形原胚,梨形原胚,分化胚和成熟胚阶段,成熟胚具有胚根,胚芽,盾片,胚牙鞘,胚根鞘,外胚叶等典型禾本科植物成熟胚的结构,胚乳发育类型为核型,包括游离核阶段,细胞化阶段和生长成熟阶段,待大量游离核形成之后才形成细胞壁,紧贴胚囊的一层胚乳细胞最后形成种子的糊粉层,其余的胚乳细胞最后充满淀粉粒,其特点为：（1）有双球形原胚的现象;（2）反足细胞解体较早;（3）胚乳游离核时期和细胞时期胚乳细胞核的核仁多样。     

鹤望兰开花结果特性

鹤望兰在亚热带厦门地区引种露地栽培,观察结果表明,实生苗始花期为4年生,全年开花,夏、秋季为盛花期,冬季产花量少。每枝花序均可产生多个果实,每个果实有种子10粒以上,果实成熟期80~140d。并观测了株高生长与种子发芽特性     

Diversity of flowering and fruiting phenology of trees in a tropical deciduous forest in India

BACKGROUND AND AIMS: In the dry tropics, vegetative phenology varies widely with tree characteristics and soil conditions. The present work aims to document the phenological diversity of flowering and fruiting with reference to leafing events in Indian dry-tropical tree species. METHODS: Nine tree species, including one leaf-exchanging and eight deciduous showing varying leafless periods, were studied. Monthly counts of leaves, flowers and fruits were made on 160 tagged twigs on ten individuals of each species for initiation, completion and duration of different phenological events through two annual cycles. KEY RESULTS: Variation in flowering relative to leaf flushing (which occurred just prior to or during a hot, dry summer) revealed five flowering types: summer flowering (on foliated shoots), rainy-season flowering (on foliated shoots following significant rains), autumn flowering (on shoots with mature leaves), winter flowering (on shoots undergoing leaf fall) and dry-season flowering (on leafless shoots). Duration of the fruiting phenophase was shortest (3-4 months) in dry-season and winter-flowering species, 6-9 months in rainy-and autumn-flowering species, and maximum (11 months) in summer-flowering species. A wide range of time lag (<1 to >8 months) between the start of vegetative (first-leaf flush) and reproductive (first-visible flower) phases was recorded in deciduous species; this time lag was correlated with the extent of the leafless period. A synthesis of available phenological information on 119 Indian tropical trees showed that summer-flowering species were most abundant (56 % of total species) amongst the five types recognized. CONCLUSIONS: The wide diversity of seasonal flowering and fruiting with linkages to leaf flush time and leafless period reflect the fact that variable reproductive and survival strategies evolved in tree species under a monsoonic bioclimate. Flowering periodicity has evolved as an adaptation to an annual leafless period and the time required for the fruit to develop. The direct relationship between leafless period (inverse of growing period) and time lag between onset of vegetative and reproductive phases reflects the partitioning of resource use for supporting these phases. Predominance of summer flowering coupled with summer leaf flushing seems to be a unique adaptation in trees to survive under a strongly seasonal tropical climate.     

白桦胚珠发育及胚、胚乳发育关系的研究

以30年生白桦(Betula platyphylla)的雌花序为材料,研究了白桦有性生殖期间胚珠和胚乳的发育过程,以及胚和胚乳发育之间的关系。观察结果表明:白桦为合生心皮雌蕊,花柱2,子房室2,每室1~2个胚珠或无,中轴胎座,倒生胚珠,单层珠被,厚珠心发育;胚柄短小,由三个细胞构成;在历时4个月之久的雌配子体形成、胚胎发育直至成熟期间,胚珠经历了形态结构的变化和适应;在胚的发育过程中,胚乳起主要营养作用,胚乳发育类型为核型胚乳。最后对胚、胚乳发育的解剖结构及其相互关系以及影响种子质量的各环节进行了研究和讨论。     

羊草受精作用及其胚与胚乳早期发育的观察

利用常规石蜡制片方法研究了羊草受精过程及胚与胚乳的早期发育,其主要结果为：(1)授粉后1h,花粉管破坏1助细胞,释放2精子。精子为眼眉状,难以区分其细胞质鞘;(2)授粉后1～2h,2个精子分别移向卵细胞与极核;(3)授粉后2～3h,精核分别贴附于卵细胞与极核核膜上;(4)授粉后3～10h,精核与卵核融合,并出现雄性核仁,形成合子;(5)授粉后3～4h,精核与极核融合,并出现雄性核仁,形成初生胚乳核,精核与极核的融合比与卵核融合快;(6)传粉后20h,合子分裂,合子的休眠期为10h左右;(7)传粉4h,初生胚乳核分裂,初生胚乳核没有休眠期;(8)羊草双受精作用属于有丝分裂前配子融合类型;(9)胚胎发育属于紫菀型,胚乳发育属于核型胚乳。     

Genomic imprinting and endosperm development in flowering plants

Genomic imprinting, the parent-of-origin-specific expression of genes, plays an important role in the seed development of flowering plants. As different sets of genes are imprinted and hence silenced in maternal and paternal gametophyte genomes, the contributions of the parental genomes to the offspring are not equal. Imbalance between paternally and maternally imprinted genes, for instance as a result of interploidy crosses, or in seeds in which imprinting has been manipulated, results in aberrant seed development. It is predominantly the endosperm, and not or to a far lesser extent the embryo, that is affected by such imbalance. Deviation from the normal 2m:1p ratio in the endosperm genome has a severe effect on endosperm development, and often leads to seed abortion. Molecular expression data for imprinted genes suggest that genomic imprinting takes place only in the endosperm of the developing seed. Although far from complete, a picture of how imprinting operates in flowering plants has begun to emerge. Imprinted genes on either the maternal or paternal side are marked and silenced in a process involving DNA methylation and chromatin condensation. In addition, on the maternal side, imprinted genes are most probably under control of the polycomb FIS genes.     

不同光质补光对火龙果茎生理特性及开花结果的影响

为探究不同光质补光对火龙果茎生理特性的影响,该文采用红光、白光、蓝光3种不同光质对火龙果进行夜间补光,测定火龙果茎中可溶性糖、可溶性蛋白、叶绿素、线粒体蛋白、线粒体膜电位及细胞分裂素(CTK)、吲哚乙酸(IAA)、赤霉素(GA)3种内源激素的含量,并统计茎长、开花数、果实产量相关指标.结果表明:3种光质补光均可提高火龙...