多胚水稻品系APⅣ不同类型胶囊的受精及其胚胎形成

FERTILIZATION OF DIFFERENT TYPES OF EMBRYO SACS AND ITS EMBRYO FORMATION IN POLY-EMBRYONIC RICE STRAIN APⅣ

通过GMA半薄切片技术对APⅣ不同类型水稻(Oryza sativa L.)胚囊的受精及其胚胎发育的研究表明,APⅣ中5-2-l型胚囊的3个卵细胞在少数情况下都可受精并发育形成3个胚;但多数情况只有 1个或2个卵细胞受精发育成1个胚或2个胚。6-2-0型和5-3-0型胚囊多个卵受精频率都很低。由此证明APIV多胚是来自如5-2-1型胚囊的多卵卵器胚囊多个卵细胞都受精的结果,其中3胚来自3个卵细胞受精发育,2胚来自2个卵细胞受精发育。双套结构胚囊受精最为复杂,多数情况是受精不正常,只有少数子房大、小胚囊中的卵细胞都能正常受精。大胚囊中的卵细胞受精发育可能是形成所谓中位胚(远离珠孔端胚)的主要原因。

The fertilization and its embryo formation of different types of embryo sacs were studied by using the technology of GMA half-section in the APIV strain of polyembryonic rice ( Oryza sativa L.). In rare cases, all three egg cells in the embryo sac of 5-2-1 type could fertilize and develop into three embryos. But in most cases only one or two egg cells fertilized and developed into one or two embryos in the respective type of embryo sac. The frequency of poly-egg fertilization in total all was very low in the embryo sac of 6-2-0 type and 5-3-0 type. These results indicated that the polyem-bryos in APIV originated mainly from overall fertilization and development of the embryo sac with poly-egg apparatus.This was observed,for example,in 5-2-1 type in which three embryos were fertilized and developed from three egg cells and two embryos from two egg cells. The fertlization process of double set of embryo sac was most complicated, all often abnormal. Only in few ovaries the egg cells in both large and small embeyo sac could fertilize simultaneously. The fertilization and development of egg cells in the large embryo sac might be the main cause of the formation of the so called 'mid-seated embryo' (the embryo far from the micropyle end).