水稻胚囊形成过程与分期

 利用改进的GMA半薄连续切片技术对水稻品种IR36胚囊形成和发育进行了研究。结果表明：a)大孢子母细胞减数分裂Ⅰ形成的二分体和减数分裂Ⅱ形成的四分体的各个子细胞的大小都是不均等的；b)单核胚囊的3次有丝分裂的方向都较为固定；c)极核发育过程有明显的形态特征变化；d)胚囊形成各阶段淀粉粒出现与否有规律性。根据IR36胚囊形成的特点，初步将水稻胚囊形成过程分为8个时期，即孢原细胞形成期、大孢子母细胞形成期、大孢子母细胞减数分裂期、功能大孢子形成期、单核胚囊形成期、胚囊有丝分裂期、八核胚囊发育期和胚囊成熟期。

The Process of Embryo Sac Formation and its Stages Dividing in Rice

The process of embryo sac formation and development in rice (cultivar IR36) was studied by the modified GMA semi-thin serial sectioning technique. Clear photos of various embryo sac formation stages were tamed. The results showed: a) The cells of dyad and tetrad from megasporocyte meiosis Ⅰ and meiosis Ⅱ were all unequal in size. b) Fixed patterns of orientation of the three mitotic events in the mono-nucleate embryo sac. c) Obvious changes in the process of polar-nuclei development were observed. d) Regular changes in the appearance and disappearance of starch grains existed in each stage of embryo sac formation. According to the characteristics of embryo sac formation, the process of rice embryo sac formation could tentatively be divided into 8 stages, i. e, archesporial cell formation stage, megasporocyte formation stage, megasporocyte meiosis stage, functional megaspore formation stage, mono-nucleate embryo sac formation stage, embryo sac mitosis stage, eight-nucleate embryo sac developing-stage, and embryo sac matured-stage. The relationships between the stages of embryo sac development and the morphological changes of spikelet were also described.