ULTRASTRUCTURE AND DEVELOPMENT OF THE NEXINE AND INTINE IN THE POLLEN WALL OF SILENE ALBA (CARYOPHYLLACEAE)

Nexine and intine development in Silene alba (Caryophyllaceae) was investigated by electron microscopy and enzyme cytochemistry. Nexine-2 forms by deposition of sporopollenin along unit membrane lamellae closely associated with the microspore plasma membrane in the late tetrad stage. After the callose wall dissolves, electron density increases along the tangentially oriented fibers of the proximal primexine, forming nexine-1. When the exine is essentially complete, the intine begins to develop. In the nearly mature microspore, acid phosphatase activity appears in the peripheral cytoplasm just prior to its extrusion into the intine of the mature pollen grain.     

白刺小孢子和雄配子体发育的超微结构研究

对白刺小孢子和雄配子体发育的各个阶段进行了超微结构研究,结果表明在造孢细胞时期,药室内壁细胞形成“分隔细胞”;绒毛毡层细胞为分泌型,但后期完全解体而形成大量的原生质团;造孢细胞质浓,细胞器丰富;母细胞显示休眠细胞的特征;上孢子具有很厚的外壁内层;花药表皮具很厚的角质层等特征可能是旱生环境的适应。     

山明桐小孢子败育及与小孢子囊壁发育异常的关系

作者研究了山明桐(Paulownia sp.)小孢子败育及小孢子囊壁异常发育的过程,并探讨了两者之间的关系。结果表明:小孢子败育发生在减数分裂至单核小孢子期间。在小孢子有丝分裂前小孢子已全部敗育拚辈惴⒂斐V饕硐衷诒3只疚唇到饣虬虢到庾刺敝脸墒旎ㄒ┦逼凇R┦夷诒谙赴┓只鎏踝丛龊裣赴凇P℃咦幽冶诜⒂械恼庑┮斐O窒蟮氖抵适瞧湔7⒂瘫恢型就V?而以幼态保持至花药最后干缩。观察表明小孢子囊壁发育异常不是小孢子败育的原因,而可能是其结果。     

Development of Plastids in Pollen and Tapetum of Rye-grass, Lolium perenne L

Proplastids of both tapetal cells and microsporocytes were presentearly in anther development. Tapetal proplastids differentiated—probablyinto elaioplasts—at late microspore stage. The tapetalcytoplasm was completely resorbed by early tricellular pollenstage. Microspore proplastids differentiated into amyloplastsat early bicellular stage, and were present in both vegetativeand generative cells. In the generative cell, the amyloplastswere ephemeral and apparently degenerated within autophagicvacuoles. Plastids were absent from sperm cells. Vegetativecell amyloplasts increased in number apparently by fission suchthat one amyloplast produced one amyloplast and one proplastidper division. Mature pollen grains were estimated to containbetween 550 and 820 amyloplasts with only one starch granuleper plastid. Elaioplasts, amyloplasts, plastid division, plastid differentiation, starch granules, autophagy, Lolium perenne, Poaceae, rye-grass     

枸杞花药发育过程中脂滴和淀粉粒的分布特征

宁夏枸杞(Lycium barbarurn L．)花药发育过程中,淀粉粒和脂滴两种营养物质的积累和分布具有一定的特点：在造孢细胞时期,药隔薄壁细胞,表皮和药室内壁细胞中开始积累淀粉粒,而造孢细胞、绒毡层细胞和中层细胞中则没有淀粉粒。在四分体时期,绒毡层细胞开始积累脂滴并且数量逐渐增加。到小孢子晚期,绒毡层细胞降解,内含脂滴流入药室中。在小孢子发育过程中既没有淀粉粒也没有脂滴积累,直到二胞花粉的大液泡消失后花粉粒中才开始积累脂滴,然后又开始出现淀粉粒。枸杞成熟花粉中的营养储存物是脂滴和淀粉粒。     

枸杞花药发育过程中钙的分布

在枸杞花药发育过程中,用焦锑酸钾沉淀的钙颗粒显示出了一个与花药发育事件有关的分布特征：在孢原细胞时期的花药中钙颗粒很少。在造孢细胞到小孢子母细胞时期,花药中钙颗粒增加。当花粉母细胞进行减数分裂时,花药中的钙颗粒进一步增加,尤其是在小孢子母细胞的胼胝质壁中。在小孢子发育早期,花药药隔部位的绒毡层细胞质中钙颗粒也明显增加并特异性地分布在其内切向壁上。当小孢子被释放出后,钙颗粒开始特异性积累在正在形成的花粉外壁中,尤其在萌发孔的部位聚集了大量的钙颗粒。当小孢子形成大液泡时,其细胞质中的钙颗粒明显减少。在小孢子分裂形成二胞花粉后,在二胞花粉的大液泡中又特异性地出现许多细小钙颗粒。随着二胞花粉的大液泡完全消失,其细胞质中又出现了许多钙颗粒。接近开花时的成熟花粉粒细胞质中,细小的钙颗粒主要分布在营养细胞和生殖细胞中。枸杞花药发育过程中钙的分布特征反映了其参与调控花粉发育过程。     

橡胶树花药和小孢子发生与发育过程的观察

应用石蜡切片法,观察橡胶树的实生树和RRIM600、CT-1品系的花药壁以及小孢子的发生和发育过程,得到如下结果:1.实生树的花药壁通常由四层细胞组成,发育形式为双子叶型。药室内壁细胞在发育后期进行径向条纹加厚,至花药开裂时仍保留着原生质体。中层由一层或不规则的两层细胞组成,在小孢子单核期消失。绒毡层细胞具单核或双核,属分泌型,至花粉发育到三细胞时消失。小孢子母细胞减数分裂为同时型。成熟花粉粒具三个细胞。精细胞椭圆形,在光镜下不能区分出细胞质鞘和核仁。所观察的实生树雄花,多数发育正常,很少有空秕的花粉。2·RRIM600品系的花药和小孢子发生与发育和实生树相似,但至后期只有少数花粉发育正常,多数成为大小不等的败育花粉;此外也有一些败有的雄花。3.GT-1的花药在小孢子母细胞减数分裂时,绒毡层细胞的体积开始异常增大并液泡化,小孢子在四分体内解体或分离后成为空秕花粉。     

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。     

白菜细胞核雄性不育花药的细胞化学观察

对一种由一对隐性基因控制的白菜细胞核雄性不育和可育株的花药进行了细胞学和组织化学研究。种子播种后,有1/4植株为不育株,其余的为可育株。通过对不育株和可育株花药发育的细胞学观察,确认不育花粉的败育发生在小孢子发育时期。用组织化学的方法研究了可育株和不育株花药发育过程中的多糖和脂类的分布动态,发现在减数分裂前,可育花药和不育花药的药隔细胞中都储藏了大量的淀粉粒。二者的差异仅是不育花药的绒毡层细胞液泡化明显。在减数分裂后的小孢子发育时期,可育花药的绒毡层细胞具有将药隔细胞中的淀粉粒多糖吸收并转化成脂类的功能,小孢子及以后的二胞花粉中也积累了大量的脂类储藏物质在不育花药中,虽然减数分裂后药隔细胞中的淀粉粒也都消失,但绒毡层细胞中的脂类物质相比很少,同时绒毡层细胞显示了明显的多糖反应,表明不育花药的绒毡层细胞将糖类转化为脂类的功能受阻。在小孢子的表面有些脂类物质,但在细胞质中却没有脂类积累。这一结果暗示在该种白菜细胞核雄性不育株中,由于花药绒毡层细胞转换多糖为脂类的功能失常,导致了小孢子的败育。     

Sporopollenin accumulation in <Emphasis Type="Italic">Nicotiana tabacum</Emphasis> L. microspore wall during its development

The paper is addressed to the accumulation of sporopollenin components in the microspore wall, sporopollenin polymerization dynamics and possible participation of reactive oxygen species (ROS) in this process. Fluorescent and transmission electron microscopy (TEM) was used. It has been revealed that phenylpropanoid components of sporopollenin accumulate in the microspore wall at the middle and late tetrad stages. At the late tetrad stage they completely cover the microspore surface and accumulate abundantly in aperture areas. In accordance with this, numerous thick sporopollenin lamellae emerge in aperture areas; the lamellae are electron dense and acetolysis-resistant. The exine in non-aperture areas includes acetolysis-resistant sporopollenin, as well as washout components. These particular parts of the wall are intensively stained with fluorescent dye MitoSOX Red, which detects the presence of ROS. The staining disappeared after the treatment of the microspore with superoxide dismutase, demonstrating the presence of superoxide in the exine. Superoxide easily converts to hydrogen peroxide, which can cause oxidative polymerization of sporopollenin components, forming a chemically stable biopolymer. The obtained data favor the hypothesis of ROS involvement in the formation of sporopollenin.