条纹龙胆的胚胎学研究(英文)

Embryology of Gentiana striata (Gentianaceae)

首次报道了条纹龙胆 (Gentiana striata Maxim.)的胚胎学特征 ,研究结果用以讨论龙胆属狭蕊组 (Gentiana Sect.Stenogyne)的系统演化关系。主要研究结果如下 :花药四室 ;药壁发育为双子叶型 ;绒毡层细胞仅来源于初生壁细胞 ,故绒毡层起源属单型起源 ,细胞具单核 ,原位退化 ,属腺质型绒毡层 ,药隔处的绒毡层细胞经多次平周分裂形成 2层至多层的绒毡层细胞 ,其余部位的绒毡层细胞仍为 1层细胞 ;中层细胞 1层 ;在花药成熟时 ,花药的表皮细胞和药室内壁均部分纤维状加厚且柱状伸长。小孢子母细胞减数分裂为同时型 ,四分体的排列主要为四面体形 ;成熟花粉为 3-细胞型。子房为 2心皮 ,1室 ,侧膜胎座。胚珠 4列。薄珠心 ,单珠被 ,珠心基部产生珠被原基 ,进而形成珠被 ,条纹龙胆仅有 1层珠被。珠被沿珠心向上生长并将珠心包围 ,于胚珠顶部形成珠孔。胚珠在发育过程中 ,整个胚珠的本体倒转 ,而且珠柄继续生长并弯曲 ,使珠孔与合点端的连线与珠柄垂直 ,形成 Hypertropous胚珠。大孢子母细胞减数分裂形成的 4个大孢子呈直列式排列 ,合点端的大孢子具功能。胚囊发育为蓼型。极核在受精前融合为次生核 ,反足细胞 3个、多宿存。雄蕊先熟。珠孔受精。胚乳发育为核型。胚胎发育为茄型酸浆 变型。

This paper describes embryological characters of Gentiana striata Maxim.For the first time,The results are used to discuss the systematic position of Gentiana Sect.Stenogyne.Anthers are tetrasporangiate.The development of anther walls conforms to the dicotyledonous type.The tapetum cells origin from the primary parietal cells,and thus the tapetum is of single origin.The development of the tapetum with uninucleate cells is of the Glandular type.The tapetal cells on the connective side show radial elongation or periclinal division and intrude into the anther locule.There are one middle layers.Parts of the epidermis and endothecium persist and the cells become pillar and fibrous.Cytokinesis in the microsporocyte meiosis is simultaneous type and the microspore tetrads are tetrahedral.Pollen grains are 3 celled.The ovary is bicarpellary and unilocular.The placentation is of reduced parietal placentae with 4 rows of ovules.The type of ovule is Hypertropous.The ovule is unitegmic and tenuinucellar.The embryo sac originates from a single archesporial cell.The one chalazal megaspore in linear tetrad becomes functional.The development of embryo sac is of the Polygonum type.Before fertilization,two polar nuclei fuse into a secondary nucleus.Three antipodal cells persist.Flowers are protandrous.Fertilization is porogamous.The development of the endosperm is of the Nuclear type.The embryogeny corresponds to the Soland type Physalis Ⅱ variation type.The present paper indicates that Gentiana Sect.Stenogyne is more similar to Tripterospermum than to other sections of Gentiana in embryological characters.Sect.Stenogyne might be separated from Gentiana .