无籽八月桔胚囊及胚胎发育细胞学观察

Cytological observation of embryo sac and embryonic development in the new mandarin cultivar‘Wuzibayueju'(Citrus reticulata Blanco)

关键词:  无籽八月桔  无籽机理  胚囊  胚胎发育

Key words:  ‘Wuzibayueju'  seedless mechanism  embryo sac  embryonic development

摘要:

运用酶解振荡压片技术和常规石蜡切片技术分别研究了无籽八月桔的胚囊育性及无籽八月桔自交和异交(无籽八月桔×台湾椪柑,无籽八月桔×有籽八月桔)的胚胎发育。结果表明:无籽八月桔胚囊可育,成熟胚囊具一个卵细胞、两个助细胞、三个反足细胞以及一个大的含二个极核的中央细胞; 其自交和异交的胚胎发育均正常,授粉后2周出现球形胚和少量心形胚,授粉后3周出现心形胚和鱼雷形胚,授粉后4周全部为鱼雷形胚,授粉后5周发育成子叶胚,授粉后7周子叶胚继续发育形成种子痕迹,仍具珠柄。可以得出,无籽八月桔胚囊育性正常,且不具胚胎中途败育现象,胚胎败育不是无籽八月桔无籽的原因。

Abstract:

Enzymolysis oscillation squash method and routine paraffin section were used to study embryo sac fertility of ‘Wuzibayueju' and the embryonic development of three pollinated combinations(‘Wuzibayueju'בWuzibayueju',‘Wuzibayueju'בPonkan',‘Wuzibayueju'בBayueju'). The results were as follows:(1)The embryo sac fertility of ‘Wuzibayueju' was normal. Mature embryo sac had one egg,two synergids,three antipodal cells and a big central cell containing two polar nuclei.(2)The embryonic development of self-pollinated ‘Wuzibayueju' and cross-pollinated ‘Wuzibayueju'בPonkan',‘Wuzibayueju'בBayueju'were normal. Two weeks after self-pollination,the zygotic embryo became globular-shaped and a few heart-shaped. Three weeks later,heart-shaped embryos and torpedo-shaped embryos were observed. Four weeks later,embryo reached at the torpedo stage. Five weeks later,cotyledonary embryos were observed. And seven weeks later,cotyledonary embryos were developing into seeds while funiculi were still existent. Those results indicated that embryo sac fertility of ‘Wuzibayueju' was normal and there was no embryo abortion during embryonic development. Therefore,the embryo abortion was not the seedless reason of the new cultivar ‘Wuzibayueju'.