A style-specific 120-kDa glycoprotein enters pollen tubes ofNicotiana alata in vivo

Pistils ofNicotiana alata (Link et Otto) contain an abundant, style-specific glycoprotein (120 kDa) that is rich in hydroxyproline and has both extensin-like and arabinogalactan-protein-like carbohydrate substituents. An antibody specific for the protein backbone of the glycoprotein was used to localise the glycoprotein in both unpollinated and pollinated pistils. The glycoprotein is evenly distributed in the extracellular matrix of the style transmitting tract of unpollinated pistils and, despite the presence of extensin-like carbohydrate substituents, is not associated with the walls of the transmitting tract cells. In pollinated pistils the 120-kDa glycoprotein is concentrated in the extracellular matrix adjacent to pollen tubes, and is also present in the cytoplasm and the cell walls of pollen tubes. Pollen tubes grown in vitro do not contain the 120-kDa glycoprotein unless it is added to the growth medium, suggesting that the 120kDa glycoprotein located in pistil-grown pollen tubes is derived from the extracellular matrix of the transmitting tract.     

Efficient microspore embryogenesis in wheat (Triticum aestivum L.) induced by starvation at high temperature

We have established an efficient method to induce embryo formation from isolated wheat (Triticum aestivum L.) microspores. Culture of excised anthers under starvation and heat shock conditions induced the formation of embryogenic microspores at high frequency in nine Austrian winter wheat genotypes, including cultivars that had been considered as recalcitrant in anther culture. Percoll gradient centrifugation of the mechanically isolated microspores allowed us to obtain homogeneous populations of embryogenic microspores in all genotypes which, after transfer to a rich medium containing immature ovaries for conditioning, divided and produced globular embryos. Thousands of embryos were produced in one petri dish. Many of these embryos developed into plantlets after transfer to a solid medium without ovaries.     

The influence of ambient temperature on the abundance of Poaceae pollen

The sampling of pollen concentrations over six seasons in north London has revealed the importance of temperature in influencing the start, severity, daily and diurnal variation of Poaceae pollen seasons. Using accumulated degree days above 6°C and rainfall amount as predictors, models have been developed which account for 96% of the variation in the starting date and 91% of the variation in the severity of the Poaceae pollen season. Maximum daily temperature is an important influence on the daily pollen count although this relationship is not linear and maximum daily temperatures within the range 21.1–25°C are associated with the highest daily pollen concentrations. Likewise, when the two-hourly variation of pollen concentration is examined, temperatures within 2–4.9°C above the normal diurnal range, rather than in excess of 5.0°C, are found to be associated with the highest two-hourly concentrations. Occasional night-time maxima of pollen concentration have also been recorded and these are examined in relation to the possibility of temperature inversions, although few conclusive results have emerged.     

花粉通量与气象要素的关系及其在预报小麦、玉米产量上的前景

应用花粉通量测定新技术,于1992～1994年在小麦(Triticum aestivum L.)、玉米(Zea mays L.)传粉期间,应用库尔式收集仪收集和测定空气中的花粉,记录气象资料,进行统计分析,确定小麦、玉米产量与它们最大传粉期空气中花粉浓度的相对应数据,根据这些数据,试图建立禹城实验区小麦和玉米产量预报图式。     

云南大叶茶体细胞胚发生及体细胞胚苗形成体系的建立

利用云南大叶茶(Camellia sinensis var.assamica Kitamura)胚性细胞系(CL_1)中悬浮培养物,建立了高频率同步化体细胞胚发生及体胚苗形成体系。以改良的MS为基本培养基,将CL_1中培养物由液体保持培养基(0.1mg/L 2,4-D 0.5mg/L 6-BA)继代转入液体诱导培养基(0.05mg/L 2,4-D 0.50mg/L6-BA),暗培养诱导28d,转入不含任何激素的液体分化培养基中再培养28d,获得了不同发育时期的体细胞胚,其发生频率为81.5％。不同发育时期的体细胞胚用不同目的细胞筛收集,在液体生长培养基(1/2 MS 1.0mg/L GA_3 0.5mg/L 6-BA)中培养发育成熟。ABA有利于高质量体细胞胚的形成。20～70月大小的体细胞胚在固体生长培养基中成苗转换率为75％。在液体悬浮培养条件下观察记录了体细胞胚发育过程,证实其过程与合子胚的形态发生过程相似。     

百合花粉母细胞核骨架的超微结构观察

参照动物细胞核骨架的研究方法,用整装电镜技术和DGD包埋-去包埋技术研究了选择性抽提的和完整的百合(Lilium davidii var. willmottiae (Wilson) Roffill)花粉母细胞。结果表明,住减数分裂前期Ⅰ,百合花粉母细胞核内存在一个精细的非染色质纤维——核骨架。该网络由5～15nm的纤维交织而成,广泛地分布于细胞核内。这些核骨架有的分布于染色体间,有的分布于染色体周围,并与染色体和核仁相连。随着减数分裂时间的推移,染色体(质)间核骨架纤维逐渐减少,染色体(质)周围的核骨架纤维逐渐增多,并与染色体内部的纤维结构相连,表明核骨架一方面为染色体拓扑变化提供一个空间支架,另一方面也可能参与了染色体骨架的构建。     

陆地棉雌蕊的花粉管生长途径中钙分布的超微细胞化学定位

用焦锑酸盐沉淀法对陆地棉(Gossypium hirsutum L.)授粉前后的柱头、花柱、珠孔与珠心组织中的钙进行了超微细胞化学定位。X射线波谱与能谱分析证明所定位的沉淀确系焦锑酸钙。观察结果表明:在整个花粉管生长途径中的雌蕊组织,钙分布均较其它相邻组织密集;钙主要分布在细胞壁与胞间基质等质外体系统中。在雌蕊中生长的花粉管,其尖端细胞器区也有丰富的钙。     

Scanning electron microscopy of microspore embryogenesis inBrassica spp.

Scanning electron microscopy was employed to study and compare microspore embryogenesis in vitro with pollen development in planta inBrassica napus andB. oleracea. An exine with its specific pattern had already been formed, when microspores were released from tetrads. During subsequent pollen development, microspores increased in size and continued to strengthen the exine. Upon in vitro culture, all microspores, i.e., embryogenic and nonembryogenic, initially showed the same morphological features. After 24 h in culture, the microspores had increased in size. Thereafter, embryogenesis was indicated in some microspores by two different morphological changes. One featured an expansion in volume of the cell cluster around the germination aperture (type I), the other showed cell cluster volume expansion over the entire microspore surface (type II). Two-thirds of embryogenic microspores in bothB. napus andB. oleracea demonstrated type I development. When followed by fluorescence microscopy, in vitro culture of microspores revealed cultures with a high embryo frequency were those with a high frequency of symmetrical division.Abbreviations SEM Scanning electron microscopy - TEM Transmission electron microscopy     

Developmental and structural aspects of somatic embryos formed on medium containing 2,3,5-triiodobenzoic acid

Cotyledon explants of ginseng (Panax ginseng C.A. Meyer) zygotic embryos produced somatic embryos at a high rate (68%) on medium without any growth regulators. Under this culture condition, apparent polar somatic embryogenesis occurred near the basal-excised portion of the cotyledons. When the cotyledon explants were cultured on medium containing 2,3,5-triiodobenzoic acid (TIBA), an auxin polar-transport inhibitor, the frequency of somatic embryo formation markedly decreased and was completely inhibited on medium containing 20 μM TIBA. On medium containing 5–10 μM, somatic embryos developed sporadically on the surface of the cotyledons and had a normal embryo axis but jar-shaped cotyledons. Embryos with jar-shaped cotyledons were also observed to occur at a high frequency when the early globular embryos formed on hormone-free medium were transferred to medium containing 20 μM TIBA. From these results, it was deduced that endogenous auxin in the cotyledon explants plays an important role in the induction of somatic embryos and that the cotyledon development in somatic embryos is also related to the polar transport of endogenous auxin. Received: 11 October 1996 / Revised version received: 8 January 1997 / Accepted: 26 January 1997     

Somatic embryogenesis and plant regeneration from immature embryos of five families of Quercus acutissima

Immature embryos of sawtooth oak (Quercus acutissima Carruth.) were obtained from five seed families and cultured on modified Murashige and Skoog nutrient medium containing 1 g/l l-glutamine and 5 mM proline and supplemented with 1.0 mg/l indole-3-butyric acid and 1.0 mg/l 6-benzylaminopurine. The frequency of somatic embryogenesis from immature embryos was a function of the collection date and seed family. The highest frequency of explants forming somatic embryos was obtained with seeds of family Chungnam 11, i.e. 7 weeks post-fertilization (90.9%) and 9 weeks post-fertilization (91.2%). No response was shown by families Chungnam 14, 15 and Jeonbook 29 (0%), at 10 weeks post fertilization. During germination, the highest frequency of epicotyl formation was obtained with Chungnam 11 (44.0%) or Chungnam 15 (43.5%), and the highest rate of radicle formation was shown by Chungnam 11 (26.1%). The most responsive seed family with respect to the formation of both epicotyl (43.5%) and radicle (26.1%) was Chungnam 11. Twenty plantlets were transplanted to a perlite:peatmoss:vermiculite (1:1:1) soil mixture, and 8 plants survived in the field. Received: 6 December 1996 / Revised version received: 18 April 1997 / Accepted: 10 May 1997