响叶杨大、小孢子母细胞减数分裂进程及其对应关系

以响叶杨(P opu lus ad enop od a M ax im.)为材料,就大、小孢子母细胞减数分裂进程及其对应关系进行了研究.结果表明:响叶杨大、小孢子母细胞减数分裂进程与花芽外部形态存在一定的相关性,可从花芽外部形态变化估计大、小孢子母细胞减数分裂进程;响叶杨大、小孢子母细胞减数分裂进程亦存在一定的时序性相关,当雄配子发育至单核靠边期时,大孢子母细胞减数分裂进入粗线期;通过相同培养条件下小孢子发育进程的观察,可以实现响叶杨大孢子母细胞减数分裂进程的即时判别.     

通辽杨花粉母细胞减数分裂及其染色体行为研究

在温室水培条件下对通辽杨(Populus simoniiCarr.×P.nigraL.‘Tongliao’)花粉母细胞减数分裂进程及其染色体行为进行了研究。结果表明:(1)通辽杨花粉母细胞减数分裂与其雄花芽/花序外部特征和花药颜色有着密切关系,前期Ⅰ作为减数分裂过程中最关键而复杂的一个阶段,大约占整个减数分裂进程90%的时间;中期Ⅰ存在单价体,后期Ⅰ有落后染色体出现,表现出较强的遗传杂合性,而且中期Ⅱ平行纺锤体的出现与天然花粉中大花粉的存在之间可能有着一定的联系;(2)在通辽杨减数分裂过程中核仁数目存在1~8个的动态变化,这种现象可能与杨属植物古多倍性起源有关,并推测通辽杨染色体组内至少存在8对带有次缢痕的染色体;(3)在同一个花芽,同一个小花,乃至同一个花药中,往往能同时观察到5~9个不同的分裂相,这种减数分裂不同步性是通辽杨适应环境的一种进化表现,对其种群繁殖具有重要意义。     

云南松小孢子发生及雄配子体形成

本文详述了云南松花粉母细胞的减数分裂、小孢子发生及雄配子体形成过程。在研究中发现:花粉母细胞在减数分裂中有明显的不同步现象;有少数发育畸形的小孢子;在减数分裂后期Ⅰ有染色单体桥及染色体片断出现;雄配子体发育过程中核分裂的方向异常;染色体数目2n=24与其它报道一致。     

紫斑牡丹栽培品种小孢子发育过程的细胞遗传学研究

本文对紫斑牡丹栽培品种的花平细胞减数分裂过程进行了系统研究,结果发现紫斑牡丹品种约６８．９６％的花平细胞在减数分裂过程表现正常,约有３１．０４％的花粉母细胞在减数分裂的比线期、中期Ⅰ、后期Ⅰ、中期Ⅱ、后期Ⅱ及四分体时期观察到染色体行为异常。本实验表明,在小孢子形成过程中,多数小孢子发育政党,但有约３１．０４％的花粉母细胞减数分裂异常,导致了花粉的败育。     

小胡杨花粉母细胞减数分裂染色体行为研究

采用常规压片法对小胡杨花粉母细胞减数分裂过程染色体行为及花粉特性进行了研究.结果表明:小胡杨花粉母细胞减数分裂过程中表现出极强的异质性,减数分裂各时期异常细胞出现率均超过70%.其中,终变期存在大量单价体、后期观察到落后染色体,证明小胡杨的两个亲本亲缘关系较远.小胡杨花粉母细胞减数分裂过程高频率异常现象(后期I落后染色体71.87%,染色体桥8.13%;末期Ⅰ有77.18%的微核细胞;后期Ⅱ有85.60%的异常细胞等)的发生直接导致其大部分花粉发育异常(99.48%),表现出远缘杂种的败育特性.     

同一居群韭莲不同植株减数分裂行为差异的遗传分析

对韭莲(2n=48)小孢子母细胞减数分裂及小孢子发育进行研究。结果显示同一居群植株的减数分裂行为存在明显差异。多数韭莲植株小孢子母细胞减数分裂存在少量落后染色体、微核等现象,平均每株中具有异常分离行为的母细胞占14.02%,小孢子发育正常,但花粉无活力。并首次从减数分裂后期Ⅰ的特殊的细胞学形态证明韭莲是臂内倒位杂合体。而少数植株韭莲的小孢子母细胞减数分裂极其紊乱,后期Ⅰ出现多极分离、大量落后染色体,小孢子母细胞减数分裂总异常分离高达94.3%。四分孢子期多分孢子体高达73.4%。分析认为:前者减数分裂行为异常的原因主要由染色体结构变异所致,而后者的原因除染色体结构变异外,还可能与控制纺锤体形成的基因突变有关。     

高羊茅花粉母细胞减数分裂及其雄性不育的细胞生理学研究

为探讨高羊茅雄性不育株A22013189的小孢子发育过程及其败育的生理学机理,以可育株189为对照,对其结实能力、花粉活力、花粉母细胞减数分裂进程中的染色体行为及生理生化特征进行研究。结果表明:(1)不育株A22013189花粉数量少,花粉粒空瘪皱褶,自交不结实,在杂交中作父本获得杂交后代的可能性极小。(2)从减数分裂前期Ⅰ至四分体时期,不育株A22013189花粉母细胞存在大量落后染色体、染色体桥和断片、微核、单价染色体、不均等分离、染色体分裂不同步、游离染色体、三分体、60°纺锤体、染色体缺失等异常现象,初步分析这些小孢子异常分裂是导致高羊茅花粉败育的细胞学原因之一。(3)不育株A22013189的可溶性蛋白质、可溶性糖含量在整个发育时期都显著低于同期可育株189;苗期至造孢细胞期,A22013189游离脯氨酸含量与可育株189无显著差异,但减数分裂期至花粉成熟期,A22013189游离脯氨酸含量却显著低于同期可育株189;苗期至造孢细胞期,A22013189丙二醛含量显著低于同期可育株189,但小孢子进入减数分裂期后,A22013189丙二醛的增加速度和积累量明显高于同期可育株189。研究发现,高羊茅雄性不育株花粉母细胞减数分裂染色体行为异常,生长发育过程存在物质能量代谢降低,有害物质积累现象。研究结果对于高羊茅败育机理研究及杂交育种亲本选择有重要的理论指导意义。     

白杨杂种三倍体小孢子母细胞减数分裂及花粉形态观察

通过醋酸洋红压片等方法观察毛新杨×银腺杨杂种三倍体小孢子母细胞减数分裂及花粉形态,以探讨杂种三倍体雄配子的育性及其细胞学机制.结果显示:(1)在小孢子母细胞减数分裂过程中可观察到部分染色体提前分向两极、落后染色体、微核等一系列染色体异常行为,表明该三倍体存在染色体的高度不平衡性.(2)在减数第二次分裂过程中存在大量胞质分裂提前现象;减数分裂产物中发现有少量二分体、三分体的存在,同时毛新杨×银腺杨杂种三倍体花粉粒的直径变化范围为22.6～62.6 μm,呈现双峰分布,由此推测有一定数量的具可育性的未减数花粉产生.     

大麦×小麦杂种愈伤组织及再生植株的细胞学观察

本文研究了Ant-13大麦×中国春小麦未成熟胚诱导的愈伤组织细胞,再生植株体细胞和花粉母细胞染色体的变化情况。发现在这三个不同分化和发育阶段中都存在着混倍体现象。但随着分化和发育过程的进行,混倍体程度越来越小,正常双单倍体细胞的比例越来越大。从再生植株花粉母细胞减数分裂前的有丝分裂开始到整个减数分裂过程中都可以看到染色体行为的异常现象,从而形成败育花粉,造成杂种不孕。花粉败育发生在单核小孢子时期。     

木立芦荟小孢子母细胞减数分裂与花粉育性关系的初步研究

文章从减数分裂过程、小孢子发育两方面,探讨了木立芦荟（Aloe arboresens Mill.）花粉败育的原因。木立芦荟花粉母细胞染色体数目为2n=14,由四对长染色体和三对短染色体组成,属二型性核型。其减数分裂异常,发现存在单价体和多价体、染色体桥、落后染色体、不均等分离、微核等。同时观察到木立芦荟染色体具有极度的粘质性,使减数分裂各阶段的染色体不易散开。统计各种异常现象出现的频率并分析了这些异常现象形成的可能机制及对正常小孢子形成的影响,推测染色体间的丝状粘连可能是木立芦荟小孢子母细胞减数分裂异常并导致败育花粉产生的主要因素。成熟花粉粒中90%以上为败育花粉,属碘败型。     

欧洲黑杨花粉母细胞减数分裂观察及其不同步性分析

以欧洲黑杨的雄花枝为材料,采用温室切枝水培和醋酸洋红染色制片法,观察花粉母细胞减数分裂进程及其与花芽发育外部形态的关系。结果表明:(1)欧洲黑杨花粉母细胞的减数分裂进程快慢与温度高低关系密切;(2)减数分裂发生时其花芽的外部形态发育没有明显变化;(3)花粉母细胞减数分裂不同步性突出,同一花药内的花粉母细胞处于不同的减数分裂时期,且同一花芽尖端发育明显滞后于中部和基部;(4)减数分裂过程中有少量的核仁异常现象,虽观察到较多平行纺锤体现象,但未发现天然2n花粉。该研究结果揭示了欧洲黑杨减数分裂的遗传变异规律,为诱变育种、倍性育种以及分子水平的进一步研究奠定了细胞学基础。     

FLOWER DEVELOPMENT IN NORMAL TOMATO AND A GIBBERELLIN-DEFICIENT (ga-2) MUTANT

Flower buds of a tomato (Lycopersicon esculentum Mill.) gibberellin-deficient mutant (ga-2/ga-2) were initiated, but did not develop to maturity and eventually aborted. If GA, was applied to a developing inflorescence or stem tip, completion of flower bud development and fruit set occurred. In development of the ga-2 flowers, the corolla and stamens did not elongate and the style was misshapen or extended past the tip of the anthers. Light microscope observations indicated that meiosis of both microsporocytes and megasporocytes did not occur. Cells of the sporogenous layer were initiated, but growth was arrested and they eventually degenerated. The ovary was normal in appearance. However, the megasporocytes degenerated, giving rise to a cavity in the ovule. Thus, although GA is not required for flower initiation in tomato, it is essential for meiosis of the microsporocytes and megasporocytes and elongation of the corolla and stamens.     

Nucleic acids in relation to cell division in Lilium longiflorum

Methods are described for preparing cell suspensions of Lilium microsporocytes, microspores and pollen grains; for obtaining cell counts of these suspensions; and for their analysis for pentose nucleic acid (PNA) and desoxypentose nucleic acid (DNA).The results of these analyses have been calculated to nucleic acid content in μμg per microsporocyte, microspore or pollen grain, and the results related to logarithm of flower bud length, an index of the developmental status of the cells, and of their temporal relationship to meiosis, microspore mitosis and opening of the flower.DNA content per cell drops sharply at the end of meiosis, with the formation of four microspores from each microsporocyte. It then increases gradually during the microspore interphase between meiosis and the microspore mitosis. At microspore mitosis DNA content doubles rapidly. In the development of the resulting binucleate pollen grain, from microspore mitosis until the opening of the flower, there is a further gradual increase of DNA content. PNA content of these cells follows the same pattern up to microspore mitosis at a level about twice that of DNA, increases sharply at mitosis, and continues to increase rapidly at a rate nine times that for DNA in the maturing pollen grain.The absolute amounts of DNA and PNA are great. At the time of anthesis the two-celled pollen grain contains about 375 μμg of DNA and 1705 μμg of PNA.     

It is a matter of timing: asynchrony during pollen development and its consequences on pollen performance in angiosperms—a review

Functional pollen is needed to successfully complete fertilization. Pollen is formed inside the anthers following a specific sequence of developmental stages, from microsporocyte meiosis to pollen release, that concerns microsporocytes/microspores and anther wall tissues. The processes involved may not be synchronous within a flower, an anther, and even a microsporangium. Asynchrony has been barely analyzed, and its biological consequences have not been yet assessed. In this review, different processes of pollen development and lifetime, stressing on the possible consequences of their differential timing on pollen performance, are summarized. Development is usually synchronized until microsporocyte meiosis I (occasionally until meiosis II). Afterwards, a period of mostly asynchronous events extends up to anther opening as regards: (1) meiosis II (sometimes); (2) microspore vacuolization and later reduction of vacuoles; (3) amylogenesis, amylolysis, and carbohydrate inter-conversion; (4) the first haploid mitosis; and (5) intine formation. Asynchrony would promote metabolic differences among developing microspores and therefore physiologically heterogeneous pollen grains within a single microsporangium. Asynchrony would increase the effect of competition for resources during development and pollen tube growth and also for water during (re)hydration on the stigma. The differences generated by developmental asynchronies may have an adaptive role since more efficient pollen grains would be selected with regard to homeostasis, desiccation tolerance, resilience, speed of (re)hydration, and germination. The performance of each pollen grain which landed onto the stigma will be the result of a series of selective steps determined by its development, physiological state at maturity, and successive environmental constrains.     

Ultrastructural Studies on the Pollen-stigma Interaction of Intersectional Hybridization in Populus

The ultrastructural changes of pollen-stigma interaction were studied under artificial pollination in intersectional crosses of Populus lasiocarpa Oliv. × P. nigra L., P. lasiocarpa Oliv. × P. simonii Cart., P. lasiocarpa Oliv. × P. adenopoda Maxim. and P. lasiocarpa Oliv. X P. lasiocarpa Oliv. The results are as follows. Before pollination, the stigmatic cells of P. lasiocarpa containing large amounts of endo- plasmic reticulum, abund ant dictyosomes and well-developed mitochondria appear physiologi- cally active. Its outer wails are covered by a layer of cuticle with numerous branching channels toward the outer space. When the pollens of P. lasiocarpa and P. nigra are dusted, respectively, to the stigma of P. lasiocarpa, the degeneration of the stigmatic cells are rather slow. The cuticle of the stigma surface just adjacent to the alighting pollen is dissolved, but the cell contents still have large amounts of endoplasmic reticulum and the structure of the membrane system remains distinctly. When the pollens of P. simonii and P. adenopoda are forced, respectively, upon the stigma of P. lasiocarpa, the stigmatic cells degenerate rapidly. In addition to the disruption of the cuticle, heavy callose is deposited on the walls of the stigma cells adjoining the dropping pollens. Numerous vesicles are formed by the rough endoplasmic reticulum, and the electron density is increasing. The structure of the membrane system disappears gradually and becomes indistinct. Osmiophilic globuli occurs in the central vacuole. Plastids accumulate starch grains. The behavior of pollen tubes of P. nigra is similar to that of P. lasiocarpa. The pollen grains germinate rapidly and the pollen tubes penetrate into the stigma after the short-tube patten. Abnormal behavior is rare. A lot of minute exudates appear on the pollen walls. As for P. lasiocarpa × P. simonii and P. lasiocarpa × P. adenopoda, only half of the tubes can penetrate into the stigma after short-tube patten and is associated with callose deposition on the walls. The other half arresting on the stigma surface shortly after germination shows abnormal behavior; such as swelling, creeping, bursting, twisting and distortion with callose deposition on the tip of the pollen tubes. As a result of our experiments, It is concluded that the degeneration speed of the stigmatic cells may be a sign of incompatibility and the crossability in progamic phase may arrange as follows: P. lasiocarpa × P. nigra, P. lasiocarpa × P. simonii, P. lasiocarpa × P. adenopoda. The first one is compatible while the second and the third are incompatible.     

丹参小孢子发生和雄配子体发育过程的解剖学研究

在显微水平上对丹参小孢子发生和雄配子体的发育过程及其与不同发育阶段花蕾的外部形态的相关性进行了研究。结果表明：丹参有2枚雄蕊,每个花药具2个花粉囊．小孢子母细胞减数分裂属同时型,小孢子在四分体中的排列属四面体型。成熟花粉粒属3细胞型并有6个萌发沟。花粉囊壁发育属双子叶型,由4层细胞构成,即表皮、药室内壁、中层和绒毡层。绒毡层细胞为腺质,二核。植株花蕾肉眼可见,大小在1～1.5mm时雄蕊孢原细胞开始分化;花蕾长至9～12mm。即从钟型花萼的钟口肉眼可见乳白色花瓣时．形成成熟的雄配子体,雄配子体具有3细胞的花粉粒。     

小盐芥小孢子发生和雄配子体发育研究

在显微水平上研究了小盐芥的小孢子发生及雄配子体发育过程,以及不同阶段与花蕾外部形态的相关性.本实验报道的小孢子发生及雄配子体发育的研究结果表明:雄蕊为四强雄蕊,每个花药具4个花粉囊.小孢子母细胞减数分裂属同时型,小孢子在四分体中的排列方式属四面体型.成熟花粉粒属3-细胞型,有3个萌发沟.花粉囊壁发育属双子叶型,由4层细胞构成——表皮、药室内壁、中层和绒毡层.绒毡层为腺质绒毡层.植株花蕾肉眼可见时,雄性孢原细胞开始分化.花蕾露白即蕾长1.1~1.7 mm时,形成成熟的雄配子体,即3-细胞花粉粒.     

THE CYTOGENETICS OF XANTHISMA TEXANUM DC. (ASTERACEAE) AND ITS B-CHROMOSOMES

The karyotype of A-set and B-chromosomes of Xanthisma texanum DC. are described in detail and measurements are given. The distribution of B-chromosomes in stem tissue is described and the loss of B-chromosomes from primary roots confirmed. The number of B-chromosomes in pollen mother cells was constant within single inflorescence buds and in all buds throughout the flowering period. The behavior of one and two B-chromosomes during meiosis is described in detail. During meiosis, B₁'s divided in 71% of the cases during anaphase II and in 29% of the cases during anaphase I. First anaphase division resulted in some lagging and elimination of B-chromatids during second division. During anaphase I, B₁₁'s divided into chromosomes and in anaphase II these divided into chromatids in 95% of the cases. In the other 5 % non-disjunction of the B-chromosomes or chromatids and A-set chromosome abnormalities occurred. Post meiotic preferential distribution during pollen mitosis resulting in a doubling of the number of B-chromosomes passed to progeny via pollen occurred, but no doubling occurred in the female line. Crosses involving plants with two B-chromosomes each yielded fewer plants with three B-chromosomes than expected. Polyploidy is extremely rare in the species. The evolutionary significance of B-chromosome behavior is discussed in relation to its origin and survival.     

Cytological and morphology characteristics of natural microsporogenesis within Camellia oleifera

Camellia oleifera is believed to exhibit a complex intraspecific polyploidy phenomenon. Abnormal microsporogenesis can promote the formation of unreduced gametes in plants and lead to sexual polyploidy, so it is hypothesized that improper meiosis probably results in the formation of natural polyploidy in Camellia oleifera. In this study, based on the cytological observation of meiosis in pollen mother cells (PMCs), we found natural 2n pollen for the first time in Camellia oleifera, which may lead to the formation of natural polyploids by sexual polyploidization. Additionally, abnormal cytological behaviour during meiosis, including univalent chromosomes, extraequatorial chromosomes, early segregation, laggard chromosomes, chromosome stickiness, asynchronous meiosis and deviant cytokinesis (monad, dyads, triads), was observed, which could be the cause of 2n pollen formation. Moreover, we confirmed a relationship among the length–width ratio of flower buds, stylet length and microsporogenesis. This result suggested that we can immediately determine the microsporogenesis stages by phenotypic characteristics, which may be applicable to breeding advanced germplasm in Camellia oleifera.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12298-021-01002-5.