千里光配子体发育、配子形成与双受精的细胞学特征（英文）

Cytological Features of Gametophyte Development and Zygotic Formation in Senecio scandens Buch.-Ham. ex D. Don(Compositae)

千里光(Senecio scandens Buch.-Ham.ex D.Don)是具有良好开发前景的传统抗菌中草药。为了探讨该物种有性生殖的细胞学机制,实现在物种的遗传育种过程中的指导作用,本研究从细胞学角度观察了千里光配子体发育、配子形成和双受精作用。结果表明,在生殖核分裂为精细胞的过程中,其位置和形态呈现差异,表现为"二态"精细胞;此外,雌配子体的形成符合孢子发育模式,成熟胚囊的形态结构为卵形或梨形,成熟的卵细胞和极核位于珠孔端。根据上述结果可推断,合子在随后二分裂时表现为"基细胞—顶细胞"极性,可能与"二态"精细胞导致的合子细胞质不均一有关。此外,从植物分类学角度,千里光的"二态"精细胞,胚囊极性和合子极性可成为菊科近缘植物分类的细胞学依据。

Senecio scandens Buch.-Ham.ex D.Don(Compositae)is a crucial plant source of Chinese traditional medicine with antibacterial properties.To obtain basic knowledge for an insight into its cytology mechanism and further practical breeding application in this species,we focus on characterizing progress on gametophyte developments and zygote formation in this paper.Based on a chronological description of the male gametic development,two dimorphic sperm cells release from their separate position in the male germ unit.Moreover,mature embryo sac exhibits an ovoid to pyriform shape locating at wider micropylar extreme,by following the monosporic pattern on development of embryo sac in the current species.It is therefore reasonable to deduce that the origin of apico-basal polarity of zygotic embryo may be related to an unevenly spaced distribution of cytoplasm in zygotic embryo which results from fertilization between the dimorphic sperm cells and the polar ovule.As the distinguishable characteristics,these morphological features will be usefulness for the taxonomy studies in other Compositae species,including dimorphic sperm cells,polar embryo sac and zygotic polarity.