J Integr Plant Biol. ›› 1991, Vol. 33 ›› Issue (1): -.

• Research Articles •    

Embryology of Astragalus mongholicus Bge.

Tian Guo-wei and Shen Jia-heng   

Abstract: This paper describes the microsporogenesis and development of the male gametophyte, me gasporogenesis and development of the female gametophyte, the double fertilization and development of the embryo and endosperm in Astragalus mongholicus Bge., the main results are as follows: 1. The male archesporium differentiates from a series of cells under the epidermis of the anther. The microspore tetracls are tetrahedial and the cytokinesis of the microspore mother cells in meiosis is the simultaneous type. The development of anther walls conforms to the monocotyledonous type. The tapetum, of which each cell contains one or many calcium oxalate crystals and always remains uninucellate, is the secretory type. The mature pollen grain is the two-celled type. 2. It is of uniovary and of multiovule being bitegeminous, crassinucellate and campylotropous, and the development of the embryo sac conforms to the Polygonum type. The female archesporium differentiates from many cells under the subhypodermis of nucellus. The four megaspores that the first one, or the second one, or the third one towards the chalazal end is functional arrange in a line. The mature embryo sac has a caecum structure. 3. The pollen tube enters into embryo sac through a degenerated synergid. The double fertilization belongs to the premitotic type of syngamy. 4. The development of the embryo belongs to the Onagrad type and the development of the endosperm belongs to the nuclear type. The endosperm cells start to form during the stage of the globular proembryo. The phenomenon of free nuclei gathering and fusing in the end of the embryo sac, amitosis of free nuclei and fusing of many nuclei in anendosperm cell have been seen during the development of the endosperm.

Key words: Astragalus mongolicus Bge., Microspore, Male gametophyte, Megaspore, Female gametophyte, Double fertilization, Embryo, Endosperm

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