千里光合子胚和胚乳形成及其早期发育的细胞学特征（英文）

Embryological features of early development of zygotic embryo and endosperm in Senecio scandens(Compositae)

千里光(Senecio scandens Buch.-Ham. ex D. Don)是传统中草药,抗菌功效显著。本研究从细胞学角度对千里光合子胚和胚乳的形成与发育进行观察研究。结果显示,结构和功能迥异的基细胞和顶细胞源自细胞质不均一分布的合子所致,推测合子的极性与胚囊的极性和生殖核分裂为"二态"精细胞有关;基细胞在合子胚胎"球型期"末期出现分化,早期胚胎的组织分化始于"三角期",可辨别的结构差异直到"鱼雷期"才出现。此外,胚乳形成遵循无细胞壁核化模型。本研究对千里光细胞分化、组织分化和结构差异各发育阶段特征的观察结果,不仅可为深入分析胚胎发育过程功能基因的时空表达提供依据,也为相关近缘物种的系统植物学研究提供参考资料。

Senecio scandens Buch.-Ham.ex D.Don(Compositae)plays a crucial antibacterial role in Chinese traditional medicines.Here,we characterized the development of the zygotic embryo and endosperm of this species to obtain basic knowledge regarding its cytological mechanism and practical breeding application.Based on chronological description of the embryogenesis events,the oblique first division in the zygote indicated that the origin of the apico-basal polarity of zygotic embryo development was established by the polar ovule.We deduced,therefore,that cell differentiation was attributable to an unevenly spaced distribution of cytoplasm in the zygotic embryo,where the ovule polarity impinged on the polar orientation of the embryo sac,egg cell,and thereby zygotic embryo.The recognizable developmental structure appeared at the torpedo stage,suggesting that tissue differentiation could be related to the signal substance throughout the outer and inner cells.Moreover,endosperm development followed the nuclear type model,resulting from the initial endosperm nuclei repeatedly dividing without cell wall formation.These representative morphological features of embryo development will be useful for further studies on functional genes,in vitro fertilization,and haploid plant production in this species.