‘新新2’和‘温185’核桃无融合生殖的解剖学研究

Anatomy of apomixis in 'Xinxin 2' and 'Wen 185' walnut

【目的】摸清新疆核桃品种无融合生殖的发育特点及类型,为缩短核桃遗传纯化周期、加快核桃优良品种选育提供理论依据。【方法】采用石蜡切片法对‘新新2’和‘温185’2个新疆核桃品种无融合生殖胚乳和胚发育过程中组织结构变化进行观察。【结果】核桃胚囊历经10 d左右发育成熟,具7细胞8核结构;2极核融合后经多次分裂形成胚乳细胞,历经8 d左右。供试的2个品种无融合生殖胚均由卵细胞分裂发育而来,卵细胞经分裂形成2细胞原胚、4细胞原胚、8细胞原胚到多细胞原胚,后期胚胎经球形期、心形期、鱼雷形期、成熟期发育完成,历经10 d左右。【结论】供试的2个核桃品种胚囊属蓼型,无融合生殖胚乳细胞由2极核融合发育而来,属核型胚乳,无融合生殖胚由卵细胞直接发育而来,属孤雌生殖类型。

【Objective】 To find out the developing features and types of the apomixis in Xinjiang walnut varieties, to shorten the walnut genetic purification cycle, and to provide theoretical basis for breedin.【Method】 The organization structural changes in the process of the endosperm and embryo development of apomixis in the two Xinjiang walnut varieties were observed by paraffin method. 【Result】 The results showed that ten days were needed for the development and maturation of walnut embryo sac with seven cells and eight nucleus. The two polar nucleus became endosperm cells by the several times of division,which took about eight days after their fusion. The all of apomixis embryos of two tested varieties were achieved by the egg cell division and its development; the egg cells became two cell proembryo, four cell proembryo, eight cell proembryo and multicellular proembryo by cell division; The postembryonic development went through the globular stage, heart-shaped stage, torpedo-stage and mature period, which needed about ten days. 【Conclusion】 The embryo sacs of two tested walnut varieties belonged to polygonum type, and the apomixis endosperm cells came from two polar nucleus by nuclear fusion and development which belonged to nuclear endosperm type. The apomixis embryos directly came from the egg cell development which belong to the parthenogenesis type.