核桃楸的胚胎学研究（Ⅰ）——小孢子发生及雄配子体发育

通过石蜡制片技术对小孢子的发生和雄配子体发育过程进行了系统的研究。结果表明：花药含有4个花粉囊;花粉囊壁包括表皮、纤维层、中层、绒毡层;花药壁发育属基本型,腺质绒毡层,中层和绒毡层在花粉发育过程中逐渐解体,成熟的花粉囊只保留表皮和纤维层。小孢子母细胞减数分裂中,细胞质分裂是同时型。四分体排列方式为四面体型,四分体解体产生单核花粉粒,成熟花粉为2-细胞型。     

黄顶菊小孢子发生与雄配子体发育的研究

利用常规石蜡切片技术,观察了黄顶菊小孢子发生及雄配子体发育过程.结果表明:(1)花药具4个花粉囊,花药肇发育为基本型,由4层细胞构成一表皮、药室内壁、中层和绒毡层,绒毡层属于变形型,其细胞为双核;(2)从孢原细胞出现到二细胞花粉粒形成,同一花药四个花粉囊的发育不同步;(3)孢原细胞为单孢原起源;小孢子母细胞减数分裂为连续型,形成的四分体为四而体型排列;(4)成熟花粉粒为二细胞型,三个萌发孔,花粉外壁具有明显的刺,偶尔观察到巨大花粉;(5)小孢子母细胞时期,花药壁中层毗邻绒毡层的一面产生外绒毡层膜,包被绒毡层和小孢子母细胞.     

毛百合小孢子发生和雄配子体发育过程的解剖学研究

在显微水平上对毛百合小孢子发生和雄配子体的发育过程与不同发育阶段花蕾的外部形态的相关性进行了研究.结果显示:毛百合每个花药具4个花粉囊,小孢子母细胞减数分裂属连续型,小孢子在四分体中的排列属左右对称型,也有少数四面体型.成熟花粉粒属2-细胞型,并有1个萌发沟.花粉囊壁由4层细胞构成,即表皮、药室内壁、中层、绒毡层.绒毡层细胞为腺质,出现多核现象.研究发现花蕾大小与小孢子各发育时期密切相关.     

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.     

芡实绒毡层细胞发育的超微结构变化

芡实（ Ｅｕｒｙａｌｅｆｅｒｏｘ Ｓａｌｉｓｂ） 绒毡层细胞在小孢子母细胞时期, 质体出现明显的变形期,细胞中二核常相互贴近或呈嵌合状态, 细胞壁间层中胞间连丝发达。减数分裂期, 绒毡层细胞壁融解消失, 胞间连丝断离, 细胞间发育出现不同步现象。质体开始积累淀粉, 部分质体呈空泡状, 并出现质体膜内陷, 这与液泡具相似的功能。四分体时期, 绒毡层细胞内部结构开始解体。单核小孢子时期, 绒毡层细胞解体消失, 使小孢子后期发育的营养来源受到影响,作者认为这是生产上成熟花粉囊中花粉粒少而且发育不正常的主要原因之一。     

金银忍冬雌雄配子体发育的解剖学研究

对金银忍冬(Lonicera maackii(Rupr.)Maxim)大、小孢子的发生和雌、雄配子体的发育过程进行了研究,结果表明:(1)4月上中旬,幼嫩的花粉囊壁由表皮、纤维层、中层和绒毡层共4层细胞组成,绒毡层类型为变形绒毡层。4月15日左右小孢子母细胞进行减数分裂形成四面体型四分体,四分体时期后,部分小孢子为空瘪状态。4月23-26日即将开花时形成三细胞型的成熟花粉。(2)子房三心皮,中轴胎座,胚珠倒生,单珠被,薄珠心。4月下旬开花前发育形成成熟胚囊,胚囊的发育为蓼型,合点端具有承珠盘。研究结果表明金银忍冬雌雄配子体的发育均属正常。     

羽叶薰衣草雄性不育的细胞学研究

用光镜和电镜观察羽叶薰衣草(Lavandula pinnata L.)雄性不育小孢子发育过程的细胞形态学特征.结果表明:羽叶薰衣草花药4枚,每枚花药通常具4个小孢子囊.花药壁发育为双子叶型,从外向内分为表皮、药室内壁、中层和绒毡层4层细胞.减数分裂形成的四分体为四面体及十字交叉型.小孢子的发育过程可分为造孢细胞期、减数分裂时期、小孢子发育早期、小孢子发育晚期.未观察到二胞花粉期和成熟花粉期.羽叶薰衣草花粉败育主要发生在单核花粉时期,细胞内物质解体并逐渐消失变成空壳花粉或花粉皱缩变形成为各种畸形的败育花粉.在此之前小孢子的发育正常.羽叶薰衣草小孢子不育机制体现在绒毡层过早解体、四分体时期以后各细胞中线粒体结构不正常、胼胝质壁与小孢子母细胞脱离、花药壁细胞中淀粉出现时间异常等. 壁发育为双子叶型,从外向内分为表皮、药室内壁、中层和绒毡层4层细胞.减数分裂形成的四分体为四面体及十字交叉型.小孢子的发育过程可分为造孢细胞期、减数分裂时期、小孢子发育早期、小孢子发育晚期.未观察到二胞花粉期和成熟花粉期.羽叶薰衣草花粉败育主要发生在单核花粉时期,细胞内物质解体并逐渐消失变成空壳花粉或花粉皱缩变形成为各种畸形的败育花粉.在此 前小孢子的发育正常.羽叶薰衣草小孢子不育机制体现在绒毡层过早解体、四分体时期以后各细胞中线粒体结构不正常、胼胝质壁与小孢子母细胞脱离、花药壁细胞中淀粉出现时间异常等. 壁发育为双子叶型,从外向内分为表皮、药室内壁、中层和绒毡层4层细胞.减数分裂形成的四分体为四     

一叶萩小孢子发生和雄配子体发育北大核心CSCD

采用石蜡切片法对一叶萩(Flueggea suffruticosa(Pall.)Baill.)的小孢子发生及雄配子体的发育过程进行了解剖学研究。结果表明:一叶萩雄花含5枚雄蕊,每个花药4个花粉囊,但有个别雄花仅含4枚雄蕊,且其中一枚具7～8个花粉囊;不同花药以及同一花药各花粉囊发育不完全同步;花药壁发育为基本型,由外到内依次为表皮、药室内壁、中层(2层)和绒毡层,绒毡层为腺质绒毡层;小孢子母细胞减数分裂为同时型,产生四分体为正四面体型,也有少数对称型;有部分小孢子在四分体时期败育;成熟花粉二细胞型,圆球形,具三条萌发沟;雄花内着生无子房结构只有花柱发育的退化雌蕊;在花萼和花药中发现大量结晶体。本研究为大戟科植物生殖生物学和传粉生物学研究提供了基础资料。     

S351┐1西瓜雄性不育的细胞学研究

西瓜Ｓ３５１－１雄性不育材料的细胞学观察表明：与对照的同系可育株相比,败育发生在次级造孢细胞到小孢子母细胞或小孢子四分体阶段,多数不育雄花花药中绒毡层始终未分化,药壁常由７－８层细胞组成,少数不育花药中出现绒毡层徒长现象;次级造孢细胞败育不同步,出现多核及多核仁现象,败育后期,药壁细胞逐渐解体,药室瓦解,花粉囊收缩变形。由此可见：其雄性不育与绒毡层的发育异常有直接联系。     

矮沙冬青小孢子发生和雄配子体发育的观察

对矮沙冬青（Ammopiptanthus nanus）小孢子发生及雄配子体发育过程进行了观察,结果表明：花约具4个花粉囊,花药壁发育为基本型,由表皮、药室内壁、中层（2—3层）和绒毡层组成,绒毡层为腺质型。小孢子母细胞减数分裂后胞质分裂为同时型,四分体为四面体型排列,成熟的花粉粒为二细胞型。在矮沙冬青小孢子发生及雄配子体发育过程中没有发现异常现象,认为矮沙冬青濒危不存在雄性生殖结构与发育过程异常的内在因素。     

七叶树小孢子发生及雄配子体发育研究

用石蜡切片法观察了七叶树花药的发育过程.结果表明:(1)雄蕊花药四室,花药壁完全分化时,从外到内依次是表皮、药室内壁、中层和绒毡层,花药壁发育为基本型.表皮细胞1层,发育过程中始终存在;药室内壁在花药成熟时形成带状纤维层加厚;幼小花药壁的中层3~4层细胞,在花药发育成熟时退化消失;绒毡层1层细胞,发育类型为分泌型,小孢子母细胞减数分裂时绒毡层开始退化解体,花药成熟完全消失,仅剩1层绒毡层膜.每一花药中有多列雄性孢原细胞,发生于幼小花药表皮下方;(2)小孢子母细胞减数分裂为同时型,四分体多呈正四面体排列;减数分裂过程中,小孢子母细胞外方被胼胝质壁所包被,小孢子形成后胼胝质壁逐渐消失.成熟花粉二细胞型,外形呈圆三角状,具三孔沟.     

红菜薹雄性不育系花药败育的细胞形态学观察

采用石蜡切片技术,在光学显微镜下系统研究了红菜薹(Brassica campestris L.ssp．chinensis L.var．utilis TsenetLee．)波里马胞质雄性不育系(Polima CMS)、红菜薹萝卜胞质雄性不育系(Ogura CMS)及相应保持系花药发育过程的细胞形态学特征。观察结果表明：红菜薹Polima CMS花药发育受阻于孢原细胞阶段,不形成花粉,属无花粉型,此不育系花药不形成绒毡层和中层;而红菜薹Ogura CMS花药败育发生于小孢子母细胞期或四分体时期,表现为绒毡层细胞异常,挤压四分体,导致四分体和绒毡层同时解体而败育。     

一品红雄配子体发育研究

一品红花药来源于雄蕊原基,花药由表皮(1层)、药室内壁(1层)、中层(1层)、绒毡层(1层)及造胞细胞组成,花药四室,药壁发育为双子叶型。小孢子发生和雄配子体发育是经由小孢子母细胞减数分裂形成四分体,该四分体胞质分裂为同时型,四分体排列为四面体型,小孢子再经有丝分裂形成2-核花粉。花药壁层的变化是表皮在花药成熟期消失,中层在四分体时消失,药室内壁在花药成熟期形成柱状纤维层。绒毡层在单核小孢子期径向伸长,有双核或多核,另外有的绒毡层细胞形成横隔或类胎座;进入2-核花粉期,绒毡层细胞分泌颗粒物进入药室,为非典型腺质绒毡层;进入成熟期绒毡层消失。同时观察到花药发育异常现象。     

A Comparative Study of Anther and Pollen Development in Male Fertile and Male. Sterile Green Onion (Allium fistulosum L.)

Anther and pollen development in male-fertile and male-sterile green onions was studied. In the male-fertile line, both meiotic microspore mother ceils and tetrads have a callose wall. Mature pollen grains are 2-celled. The elongated generative cell with two bended ends displays a PAS positive cell wall. The tapetum has the character of both secretory and invasive types. From microspore stage onwards, many oil bodies or masses accumulate in the cytoplasm of the tapetal cells. The tapetum degenerates at middle 2-celled pollen stage. In male-sterile line, meiosis in microspore mother cells proceeds normally to form the tetrads. Pollen abortion occurs at microspore with vacuole stage. Two types of pollen abortion were observed. In type I, the protoplasts of the microspores contract and gradually disintegrate. At the same time the cytoplasm of microspores accumulates oil bodies which remain in the empty pollen. The tapetal cells behave normally up to the microspore stage and early stage of microspore abortion, but contain fewer oil bodies or masses than those in the male-fertilt line. At late stage of microspore abortion, three forms of the tapetal ceils can be observed: (1) the tapetal cells with degenerating protoplasts become flattened, (2) the tapetal cells enlarge but protoplasts retractor, (3) the cells break down and tile middle layer enlarges. In type Ⅱ, the cytoplasm degenerates earlier than the nucleus of the microspores and no protoplast is found in the anther locule. There are fibrous thickenings iii the endothecium of both types. It is difficult to verify whether the tapetum behavior and pollen abortion is the cause or the effect.     

New views of tapetum ultrastructure and pollen exine development in Arabidopsis thaliana

Background and Aims

The Arabidopsis thaliana pollen cell wall is a complex structure consisting of an outer sporopollenin framework and lipid-rich coat, as well as an inner cellulosic wall. Although mutant analysis has been a useful tool to study pollen cell walls, the ultrastructure of the arabidopsis anther has proved to be challenging to preserve for electron microscopy.

Methods

In this work, high-pressure freezing/freeze substitution and transmission electron microscopy were used to examine the sequence of developmental events in the anther that lead to sporopollenin deposition to form the exine and the dramatic differentiation and death of the tapetum, which produces the pollen coat.

Key Results

Cryo-fixation revealed a new view of the interplay between sporophytic anther tissues and gametophytic microspores over the course of pollen development, especially with respect to the intact microspore/pollen wall and the continuous tapetum epithelium. These data reveal the ultrastructure of tapetosomes and elaioplasts, highly specialized tapetum organelles that accumulate pollen coat components. The tapetum and middle layer of the anther also remain intact into the tricellular pollen and late uninucleate microspore stages, respectively.

Conclusions

This high-quality structural information, interpreted in the context of recent functional studies, provides the groundwork for future mutant studies where tapetum and microspore ultrastructure is assessed.     

垂花悬铃花雌雄配子体发育研究

对垂花悬铃花雄配子体发育观察表明,其花药由表皮(1层)、药室内层(1层)、中层(2层)、绒毡层(1层)及造孢细胞组成,花药四室,药壁发育为双子叶型。雄配子体发育经由花粉母细胞减数分裂形成四分体,该四分体胞质分裂为同时型,四分体排列方式为四面体型,十字交叉型及左右对称型;小孢子再经有丝分裂形成营养核和生殖核,生殖核再经有丝分裂形成3-核花粉。花药壁层的变化,在单核小孢子期,表皮细胞解体,仅留下痕迹;中层在花粉母细胞期逐渐消失;药室内壁在单核小孢子期开始纤维化;绒毡层在单核小孢子期消失,属变形绒毡层。雌配子体发育观察表明,其子房上位,5室,每室1个胚珠,胚珠弯生,中轴胎座,大多数胚珠发育停留在珠心形成阶段,极少数珠心形成一群孢原细胞及单核、双核胚囊。     

调控拟南芥花粉发育突变体zy1511的基因定位及特征分析

为了进一步研究花药花粉发育过程,我们通过EMS诱变,筛选到拟南芥雄性不育突变体zy1511。遗传分析表明,zy1511为隐性单位点突变。细胞学观察表明．突变体花药中小孢子从四分体释放出后绒毡层并没有开始退化,花药发育后期绒毡层依然部分存在。说明突变体花药绒毡层退化比野生型的要迟,因此,小孢子不能发育成正常花粉粒。利用图位克隆的方法将zv1511定位于第一条染色体上分子标记F25P12和T8L23之间134．kb的区间内。本项工作为zy1511基因的克隆及对花粉发育功能分析奠定了基础。目前尚未见到该区间内雄性不育基因的报道。因此,zy1511是控制花粉发育的尚未发现的关键基因。     

蜡梅小孢子发生和花粉形成的研究

通过对蜡梅小孢子发生和花粉形成的研究,结果表明：蜡梅幼小花药中的多列孢原细胞经造孢细胞发良为小孢子母细胞。减数分裂为同时型。四分体呈四面体型排列,同时观察了小孢子在发育过程中液泡的动态变化。成熟花粉为２－细胞型。花药壁的发育为双子叶型。花药壁由５－６层细胞组成,腺质绒毡层。花粉具有异型性现象。     

Receptor-like protein kinase 2 (RPK 2) is a novel factor controlling anther development in Arabidopsis thaliana

Receptor-like kinases (RLK) comprise a large gene family within the Arabidopsis genome and play important roles in plant growth and development as well as in hormone and stress responses. Here we report that a leucine-rich repeat receptor-like kinase (LRR-RLK), RECEPTOR-LIKE PROTEIN KINASE2 (RPK2), is a key regulator of anther development in Arabidopsis. Two RPK2 T-DNA insertional mutants (rpk2-1 and rpk2-2) displayed enhanced shoot growth and male sterility due to defects in anther dehiscence and pollen maturation. The rpk2 anthers only developed three cell layers surrounding the male gametophyte: the middle layer was not differentiated from inner secondary parietal cells. Pollen mother cells in rpk2 anthers could undergo meiosis, but subsequent differentiation of microspores was inhibited by tapetum hypertrophy, with most resulting pollen grains exhibiting highly aggregated morphologies. The presence of tetrads and microspores in individual anthers was observed during microspore formation, indicating that the developmental homeostasis of rpk2 anther locules was disrupted. Anther locules were finally crushed without stomium breakage, a phenomenon that was possibly caused by inadequate thickening and lignification of the endothecium. Microarray analyses revealed that many genes encoding metabolic enzymes, including those involved in cell wall metabolism and lignin biosynthesis, were downregulated throughout anther development in rpk2 mutants. RPK2 mRNA was abundant in the tapetum of wild-type anthers during microspore maturation. These results suggest that RPK2 controls tapetal cell fate by triggering subsequent tapetum degradation, and that mutating RPK2 impairs normal pollen maturation and anther dehiscence due to disruption of key metabolic pathways.