侧柏和北美香柏(柏科)的传粉机制(英)

观察了侧柏（Phaycladusorientalis（L．）Franco）和北美香柏（ThujaoccidentalisL．）散粉后花粉进入珠孔的过程。在散粉期,这两种植物的胚珠均分泌出传粉滴。当花粉落到传粉滴上后,引起传粉滴表面的形状发生改变或减弱胚珠的继续分泌,使得该传粉滴蒸腾加快,导致其比未授粉的传粉滴明显收缩。观察结果表明：不同植物的花粉导致侧柏传粉滴的收缩速率不尽相同。其中,与侧柏亲缘关系较近的植物花粉引起传粉滴的收缩速率和侧柏自身花粉引起的传粉滴收缩速率相似;反之,收缩速率变慢。侧柏传粉滴的收缩可能主要是由于花粉减弱胚珠分泌的结果。     

侧柏和北美香柏（柏科）的传粉机制

观察了侧柏和北美香柏散粉后花粉进入珠孔的过程。在散粉期,这两种植物的胚珠均分泌出传粉滴。当花粉落于传粉滴上后,引起传粉滴表面的形状发生改变或减弱胚珠的继续分泌,使得该传粉滴药膳加快,导致其比未授粉的传粉滴明显收缩。观察结果表明;不同植物的花粉导致侧柏传粉滴的收缩速度不尽相同,其中,与侧柏亲缘关系较近的植物花粉引起传粉滴的收缩速率和侧柏自身花粉引起的传粉滴收空速率相似;反之,收缩速率变慢。侧柏传粉滴     

南方红豆杉小孢子发生与雄配子体发育

采用石蜡切片法,对南方红豆杉小孢子发生及雄配子体发育过程进行了系统地观察。结果表明：南方红豆杉小孢子叶球于7月下旬分化,9月中旬形成造孢细胞,11月初形成小孢子母细胞;同一小孢子叶球中的小孢子母细胞表现出发育不同步现象;11中旬,进入减数分裂时期,形成游离小孢子后休眠越冬,于翌年1月下旬逐渐成熟,成熟花粉粒为单核;2月中下旬开始散粉,散粉时间持续15 d 左右。花粉落入胚珠后,经过3次分裂形成管细胞、柄细胞和2个精子;管细胞和柄细胞最终退化解体,未见花粉败育现象。认为南方红豆杉小孢子发生与雄配子体发育正常,不是致其濒危的主要原因。     

攀枝花苏铁传粉生物学研究

在攀枝花苏铁(Cycas panzhihuaensis L.Zhou et S.Y.Yang)自然群体中,雌雄株在数量上基本相等,但雄株的无性系产量是雌株的1.31倍,小孢子叶球的数量是大孢子叶球的2.21倍,呈现偏雄现象。小孢子叶球散粉次序是从轴基部向顶部和从小孢子叶的基部向顶部进行的,散粉高峰出现在午后,风传花粉浓度在2.55m内随着距离增加而迅速下降,而在2.55m以外维持在一个较低的水平上。在大孢子叶球内发现有两种蚂蚁和一种蜚蠊类昆虫在活动,没有发现这些昆虫对大孢子叶球的破坏,小孢子叶球则几乎没有昆虫探访。清晨在大孢子叶叶片上出现许多水样液滴,可能起着将大孢子叶叶片上沉积的花粉传递至胚珠的作用。研究表明,在攀枝花苏铁的传粉过程中,风是将花粉从小孢子叶球传至大孢子叶球的唯一媒介,大孢子叶球内活动的昆虫和大孢子叶叶片上的液滴同样起着传粉媒介作用,但不排除风传花粉一步到位的可能性。     

雄全异株植物瘿椒树（省沽油科）的传粉生物学

从开花动态、传粉昆虫、花的形态结构、繁育系统、花粉活力和柱头可授性等方面研究了我国特有珍稀植物瘿椒树（Tapiscia sinensis Oliv.）的传粉生物学特性。瘿椒树是典型的雄全异株植物,两性花中含有功能性花粉,且自交亲和,但雄花花粉活力和萌发力是两性花的10倍以上。雄株和两性植株具有相同开花物候期,花期均为5月下旬至6月上旬,单花期为4-5天,雄花和两性花的5枚花药开裂的不同步性明显延长了散粉时间。两性花雌蕊先熟,柱头可授性较长。具有适应风媒和虫媒传粉的花部特征。传粉昆虫主要为蜜蜂科（Apidae）和食蚜蝇科（Syrphidae）昆虫,访花高峰期为8：30-10：30。维持瘿椒树雄全异株的可能机制是：雄株总体上增加了异交花粉的数量和质量;两性花的雄蕊为该物种提供了繁殖保障,同时为传粉者提供了报酬。     

极小种群野生植物崖柏的生殖物候、传粉及胚胎发育研究

以濒危植物崖柏（Thuja sutchuenensis Franch.）为对象,对其生殖物候、传粉机制进行观察,并采用石蜡切片法对其胚胎发育过程进行研究。结果显示：崖柏于8月分化出大、小孢子叶球,次年3月传粉,为花粉无气囊、具传粉滴、胚珠直立型传粉机制,球果于10月开裂;显微观察发现,传粉期花粉进入珠孔后,贮藏在珠心上方的贮粉室内,同时珠心组织中分化出孢原细胞,进入雌配子体发育阶段,5月中旬,花粉管开始萌发,6月初完成受精,进入胚胎发育阶段,10月初,胚胎发育成熟。研究表明崖柏从大、小孢子叶球形成至种子成熟的整个发育过程中均存在败育,而胚珠败育及雌配子体游离核时期至幼胚发育期间的败育是其生殖障碍的主要原因。本研究获得了崖柏生殖生物学的基础资料,为其人工繁育和制定保护策略提供了重要依据。     

红豆杉的胚珠发育,传粉滴形成和传粉过程

观察了红豆杉（Ｔａｘｕｓ ｃｈｉｎｅｎｓｉｓ （Ｐｉｌｇ．）Ｒｅｈｄ）的花粉形态和水合特性及胚珠发育、传粉滴形成与传粉过程。成熟花粉为单细胞,无气吓,形状不规则,外壁表面具大量乌氏体。花粉水合时,内壁膨胀,外壁开裂。通常情况下,外壁保留在水滴或传粉滴的表面,而花粉的其他部分进入水滴或传粉滴内。在８月下旬,可观察到下弯的雌性生殖芽。下弯这一特性是雌性生殖芽区别于营养芽的重要特征。这一时期的雌性生殖芽     

雄全异株植物瘿椒树(省沽油科)的传粉生物学

从开花动态、传粉昆虫、花的形态结构、繁育系统、花粉活力和柱头可授性等方面研究了我国特有珍稀植物瘿椒树(Tapiscia sinensis Oliv.)的传粉生物学特性。瘿椒树是典型的雄全异株植物,两性花中含有功能性花粉,且自交亲和,但雄花花粉活力和萌发力是两性花的10倍以上。雄株和两性植株具有相同开花物候期,花期均为5月下旬至6月上旬,单花期为4-5天,雄花和两性花的5枚花药开裂的不同步性明显延长了散粉时间。两性花雌蕊先熟,柱头可授性较长。具有适应风媒和虫媒传粉的花部特征。传粉昆虫主要为蜜蜂科(Apidae)和食蚜蝇科(Syrphidae)昆虫,访花高峰期为8:30-10:30。维持瘿椒树雄全异株的可能机制是:雄株总体上增加了异交花粉的数量和质量;两性花的雄蕊为该物种提供了繁殖保障,同时为传粉者提供了报酬。     

刺五加、短梗五加的开花动态及繁育系统的比较研究

野外定位观测刺五加（Eleutherococcus senticosus),短梗五回（E.sessiliflorus)的开花进程,花朵的功能形态特征和开花动态,用杂交指数（OCI）,花粉－胚珠比（P／O）,去雄,套袋,人工授粉等方法分别测定刺五加,短梗五加的繁育系统,结果显示,刺五加种群,短梗五加种群的花期均持续1个月左右,刺五加比短梗五加早开花20d 左右,二均有雄蕊先熟现象,刺五加是单全异株植物,种群内既具有雄性,又具有雌株,还具有两性株,繁育系统主要为异交,需要传粉活动才能完成授粉过程,与刺五加不同,短梗五加仅具两性花,但繁育系统也以异交为主,短梗五加两性花中的雌,雄器官既在空间上分离,又在时间上分离,只能进行同株异花间或异株,异花间传粉才能受精结实。     

杉木大孢子叶球发育过程中形态结构的变化

以福州生长的成年杉木（Cunninghamia lanceolata（Lamb.） Hook.）为实验材料,采用数码相机实地拍照、体视镜、半薄切片以及扫描电镜等方法,从形态学、解剖学系统观察了杉木大孢子叶球的发育过程。结果显示,2011年10月底至11月初,杉木大孢子叶球形成,此时大孢子叶球呈绿色,体积较小;翌年3月中下旬,大孢子叶球成熟,进入传粉期,期间大孢子叶球经历了由绿变黄的颜色转变、体积增大以及苞片开张的过程。胚珠发育过程中,胚珠原基于1月上旬发生,1月中下旬珠被和珠心组织已分化形成;2月下旬,珠心组织继续发育,形态呈椭圆型,并在其上方形成贮粉室,周围的珠被组织继续生长包围珠心组织,形成珠孔道;3月初珠孔形成,开口达到最大,胚珠的体积继续增大;3月中下旬,胚珠珠孔处开始分泌传粉滴。授粉后,传粉滴消失,珠孔上方的组织停止生长,珠孔开口亦不再增大。研究结果表明杉木大孢子叶球从分化形成到发育成熟需要约5个月的时间,胚珠的形态结构经过长期演化形成了许多适应风媒传粉的结构特征。     

Orientation and withdrawal of pollination drops in Cupressaceae s. l. (Coniferales)

Pollination in the Cupressaceae is studied ex situ, focused on orientation and withdrawal of pollination drops. Orientation of pollination drops is a constant feature in most taxa studied and important for pollen capture. Conspecific pollen causes a withdrawal of pollination drops, varying in time among species from 8 to 24 min, but with little variation within species. Pollination drops of each tested Cupressaceae taxon are also withdrawn when pollinated with foreign, but Cupressaceous pollen. However, they remain unchanged and are not withdrawn immediately when pollinated with pollen of other seed plants. The results clearly indicate that the time for the total withdrawal of pollination drops is strongly influenced by the evolutionary distance of the taxa being involved in the pollination process. Among closely related taxa the withdrawal is much more rapid than in distantly related ones. This points to an effective recognition system regulating the withdrawal of pollination drops, probably controlled by the nucellus. This recognition system can be regarded as an important preadaption for the evolution of a self-incompatibility mechanism. The withdrawal of pollination drops is thus not exclusively a physically induced process as suggested in some earlier studies. Pollination drops of several ovules can fuse to form a large common one, perhaps increasing by this way successful pollen capture.     

A Contribution to Pollination and Fertilization of Amentotaxus argotaenta

The present investigation was conducted during 1980–1982, and mater- ials collected from Jin-Fo shan (Golden Buddha Mountain), at a height of 1400-1600 m, Sichuan province, China. Pollination of Amentotaxus argotaenia began to proceed last week of May, and came into bloom the first week of June. The male strobiles were almost entirely wilting at June 12–15. Thus, florescence of Amentotaxus spread over a period of 3 weeks. While the pollen grains approaching to maturity, most of the microspores divide to form a larger tube cell and a smaller antheridial initial. In this case the mature pollen grains of Amentotaxus consist of two cells. Then pollen grains are attracted down into the pollen chamber in the apex of the nucellus after pollination. The pollen chamber of Amentotaxus in longitudinal section looks like a flask in shape and is very much similar to that of Ginkgo biloba. As pollen grains at pollen chamber begin to germinate, the antheridial initials divide again to give rise to a spermatogenous cell and a sterile cell. At first, the spermatogenous cell is of a size only 11–13 μ in diameter. When the pollen tube reaches the middle part of the nucellus, the spermatogeneous cell is of a size about 30 μ. In the middle of July, pollen tube approaches the top of the female gametophyte. In this time, the spermatogenous cell has already been mature enough and is of 58–85 μ in diameter. The nuclei of spermatogenous ceils, 30–36 μ in size, are usually lying in the lateral side of the cytoplasm at its micropylar end. From the middle to the end of July, spermatogenous cells divide to form two unequal sperms, one of which is larger than the other and is the functional one. The large sperm is almost round in shape and about 56 μ in diameter. The small sperm is elliptic in shape, non-functional, and about 33 μ in diameter. The nuclei of the large and small sperms are about 40 μ and 26 μ, respectively. In some cases there are lateral pollen tube and sperms in the ovules of Amentotaxus, or the pollen tube even grows toward the lower part of female gametophyte in the chalazal end and there are well developed sperms in such a case. In the middle of July, nucleus of the central cell divides to form a ventral canal nucleus and an egg nucleus. The former then breaks down quickly and the latter continues to develope and moves toward the central part of the egg cell gradually. It is interesting to note that there are a number of nucleolus-like grains in the cytoplasm of the egg cell in Amentotaxus. The large nueleolus-like grains contain a larger central vacuole with several smaller vacuoles surrounding it. These grains show a positive reaction and blue colour by PAS and aniline blue black or coomassie brilliant blue, respectively. The above facts show that the nucleolus-like grains contain not only po- lysaccharides, but also protein. Similar grains may also found in the developing pollen tube. This is a unique feature in Amentotaxus and even in Gymnosperms. Otherwise, there are often two groups of the dense cytoplasm under the egg nucleus in Amentotaxus. Fertilization of Amentotaxus took place around July 20–29 (1980–1982). Interval between pollination and fertilization was about two months. After male nucleus fuses entirely with the female nucleus, the zygote begins to divide by mitosis. During fertilization, in addition that the large sperm enters the egg cell and fuses with the egg nucleus, the small sperm, tube nucleus, and sterile cell are often delivered into the egg cell. But they are disintegrated gradual]y and eventually. It is worthy to note that the nucleolus-like grains and the starches in pollen tube are also released into the egg cell. Then enlargement, fusion, and budding in the nucleolus-like grains may be found within the cytoplasm of the egg cell after fertilization. The history of investigating Amentotaxus found in 1883 has been lasting a long period of 100 years. But researches in sex production has never been studied before. The present work has shown that fertilization in Araentotaxus is very much similar to that in Taxus, Pseudotaxus, and Torreya. In other words, they all belong to the same type, that is, mitosis of zygote taking place after fusion of the two sexual nuclei. This condition constitutes one of the features of Taxaceae. But fertilization in Cephalotaxaceae is different from that of Taxaceae in having mitosis taking place before fusion of the two sexual nuclei. Pollination of Amentotaxus is similar to that of Cephalotaxus with dual-cell pollen grains at shedding stage. On the other hand, interval between pollination and fertilization in Austrotaxus lasts for 13.5 months, and this is the longest one in Taxaceae, and it is similar to that of Cephalotaxus proceeding for 14 months. To sum up, from the point of view of pollination, fertilization, and embryogenesis, Amentotaxus could be considered a primitive type in Taxaceae. Perhaps an order of systematic position of the genera belonging to Taxaceae can be arranged thus: Amentotaxus, Austrotaxus, Taxus, Pseudotaxus, and Torreya. And Cephalotaxaceae may be related to Taxaceae by way of Amentotaxus.     

Significance of exine shedding in Cupressaceae-type pollen

In conifers, which have non-saccate Cupressaceae-type pollen, the pollen must land on a pollination drop or be picked up by the pollination drop from the surface of the cone near the ovule before it can be taken into the ovule. After contact with the drop, the pollen intine absorbs moisture from the drop, expands and the exine is shed. In this study the significance of the shedding of the exine is interpreted from experiments in which simulated pollination drops and micropyles were used to determine the movement of pollen and other particles in suspension. The non-expanded pollen, which can be observed upon contact with the pollination drop, sheds the exine, which then functions as a non-elastic particle, while the pollen from which the exine was shed swells and functions as an elastic particle because it is enclosed by the flexible intine. Non-elastic particles are not easily transferred through narrow passages (the micropyle and micropylar canal) and tend to plug these passages. However, elastic particles, such as the swollen pollen, are easily transferred along narrow passages even when non-elastic particles are present. The simulated experiments demonstrate that exine shedding is an important feature in getting pollen through the narrow micropyle and micropylar canal to the nucellus of the ovule.     

青阳参花部特征及其传粉适应性

对青阳参花（Cynanchum otophyllum）部综合特征、访花昆虫种类、访花行为及传粉过程进行了研究,结果表明,青阳参花结构复杂,两个子房基部离生、花柱联合与雄蕊形成合蕊柱,柱头表面被邻近花药的侧翼紧密包围形成5个柱头腔。青阳参的花粉形成独特的花粉块,一次传粉过程可以转运大量的花粉。东方蜜蜂（Apis cerana）是青阳参的主要传粉昆虫,其传粉包括两个过程：（1）当蜜蜂的口器或足插入着粉腺的槽口后借助蜜蜂的力量将花粉块从花上拔起;（2）当蜜蜂再次访花时将携带的花粉块插入其中一个柱头腔。花粉块里面的花粉粒住柱头腔中萌发出花粉管,然后沿着花柱道向下生长最后进入子房。在整个花期仡粉保持有相对较高的生活力,而其柱头可授性则在7天后逐渐降低。     

Pollination Biology of Cycas panzhihuaensis L. Zhou et S.Y.Yang

The population of cone-bearing cycad, Cycas panzhihuaensis L. Zhou et S. Y. Yang, was male-biased. Although the number of male individuals was almost equal to that of female individuals, the clonal and cone production of male individuals was 1.31 and 2.21 times as much as that of female individuals respectively. The sequence of pollen shedding was from the base to the top of the cone and microsporophyll. The peak of daily pollen shedding occurred at noon and in the afternoon. The airborne pollen concentration decreased quickly within 2.55 m and finally maintained at a low level along with the distance from emitting male cone. The megastrobilus was transformed into a receptive state at the beginning of pollination due to the regular morphological changes of megasporophylls. Two kinds of ants and one kind of cockroaches were found to be active within the megas- trobili during pollination, albeit causing no tissue damage. The microstrobili gave off a strong odor of fennel that could dispel all the insects nearby. The sterile foliar structure of the megasporophyll was able to secret aqueous droplets at dawn which might function as transporting adhered pollen grains by dislodging and accumulating them on or near micropyles during the process of droplets falling. Resuits from field observation showed that pollination of C. panzhihuaensis might be accomplished by different pollinators. Pollen grains were firstly wind-transported from microstrobili to megastrobili and then insects and secreted droplets on the megasporophyll either directly or indirectly carried the pollen grains to ovules within a megastrobilus. However, insects might play as a subsidiary pollinator due to the preferential concentration of airborne pollen grains transported to the megasporophylls.     

Ovulate cone,pollination drop,and pollen capture in Sequoiadendron (Taxodiaceae)

In Sequoiadendron ovules are borne inside the ovulate cone, and pollination drops secreted from these ovules collect pollen. We examined: (1) the relation between ovular position and pollen capture; (2) pollen behavior when in contact with a pollination drop; and (3) ultrastructure of ovules during pollination drop secretion. During wet periods a water sheet forms on the surface of the cone due to bract shape and wettability. Pollination drops persist inside the wetted cone, and pollen capture resumes immediately after drying. Pollen landing on a pollination drop is taken inside the drop and carried into the micropyle when the drop contracts. Several notable ultrastructural features appear in the nucellus, integument, chalaza, and bract lamina during pollination-drop secretion. The abaxial surface of the lamina is covered by a membrane that may contribute to the wettable nature of the surface.     

Changes in proteins and peroxidases induced by compatible pollination in the ovary of Nicotiana tabacum L. ahead of the advancing pollen tubes

Proteins and peroxidases produced by the ovules and placenta of tobacco (Nicotiana tabacum L.) in response to compatible pollination were analyzed by two-dimensional polyacrylamide gel electrophoresis and by enzyme staining in flat-bed native isoelectric focusing gels. For two-dimensional gels, ovaries were sampled at 36 h after pollination, at which time pollen tubes have penetrated much of the length of the style but have not yet entered the ovary. At least 11 major proteins from pollinated ovaries had no detectable counterparts in unpollinated ovaries. These showed a range of molecular mass and pI. For peroxidase isozyme assays, ovaries were sampled at 0, 12, 24, 36 and 48 h after pollination. At 45–50 h, pollen tubes were beginning to enter the top of the ovary but could still be separated from the ovules and placenta during sampling. Ovules and placentae from unpollinated pistils showed only one form of peroxidase, whereas those from pollinated pistils showed additional isozymes at pH 5.4 and pH 10.0. Both new isozymes increased in staining intensity over the first 36 h after pollination. At 48 h, however, the acidic peroxidase had continued to increase, while the basic component had declined so as to be barely detectable. The observations are discussed in relation to accumulating evidence that some form of pollination-induced signal reaches the ovary ahead of the advancing pollen tubes. The nature of this signal and possible involvement of peroxidases are also briefly discussed.