The stigmas of five species, Populus euphratica Oliv., P. alba L., P. simonii Carr., P. lasiocarpa Oliv. and P. nigra L. have been studied. Scanning electron microscopy re veals that exudates are present in the intercellular spaces, in the clefts between the multicel lular papillae and on the receptive surface. Release and movement of exudates can be visual ized when the fresh stigmas are stained with sudan Ⅲ and auramine O. Paraffin and semi thin resin sections of stigmas after glutaraldehyde osmium fixation evidence the lipidic nature of the exudates. Transmission electron microscopy reveals the glandular features of the stigmatic papillae cells, such as abundance of rough and smooth endoplasmic reticulum, polyribosomes, and well developed dictyosomes with secretory vesicles. Pellicle and epicuticular lamellate layers which have been considered as typical features of the dry type stigmas are also present in the species where stigmas appear extremely wet. It is concluded that stigmas in all of the five species are secretory at the receptive stage. Well developed generative and sperm cells were observed in the pollen tubes penetrating through the deep layers of the stigmatic tissue in the reciprocal crosses between P. euphratica and P. simonii, which indicated that there is no significant barrier in the stigma.
An intergeneric artificial hybridization was conducted between Cunninghamia R. Br. and Cryptomeria D.Don The results are as follows:1. A considerable number of hybrid seeds shed from 76 pollinated cones were empty and a total of 628 looks plump. Soft X ray radiographs showed that, still and all, a majority of the “plump" seeds were embryoless (597, 95.6%) whereas some were partially developed (17,2.7%) and only a few were really full (14, 2.2%). 2. Germination test showed that all of the radiographed hybrid seeds with fully developed embryos were germinable whereas those with partially developed embryos were ungerminable. 3. Physiologically, the growth rate of hypocotyl, the date for shedding of seed coat and spreading of cotyledons, the elongation of epicotyl, and the branching of shoot of the 11 month old seedlings showed a tendency to fall behind those of the female parent; morphologically, the 11 month old hybrid seedlings with linear leaves appeared rather short, slender and weak, whereas the seedlings of the female parents with linear_lanceolate leaves appeared rather tall, stout and strong. 4. It is considered that the hybrid may be true and the crossability reveals a close phylogenetic affinity of Cunninghamia with Cryptomeria.
用细胞化学方法,对大叶杨(Populus lasiocarpa Oliv.)不同发育阶段的柱头细胞进行了 ATP 酶的超微结构定位。结果表明:(1)大叶杨柱头表膜上存在 ATP 酶的定位沉淀,但ATP 酶的活性随可授期的到来而活性增加;幼嫩期和过盛花期的柱头表膜上少或无 ATP 酶活性。显示出 ATP 酶与花粉一柱头相互作用的相关性。(2)可授期柱头细胞中,ATP 酶主要定位于线粒体内嵴、叶绿体片层、内质网、核膜及核仁、质膜和胞间连丝上,高尔基体及液泡膜上无 ATP 酶活性的定位。(3)柱头细胞在衰亡中,ATP 酶转而分布于液泡膜、消化液泡膜、线粒体外膜、叶绿体被膜及膜结构的消化残片上,而原先可授期时 ATP 酶活性最高的线粒体内嵴和叶绿体片层则失去 ATP 酶的活性。
