The Fine Structural Observation on the Development of Embryo and Endosperm in the Intergene- rfc Crosses of Fadish ♀ (Raphanus sativus L.) Cabbageo ♂ (Brassica oleracea L.)
Abstract:The present report deals with the structural abnormalities and abortion of the endosperm, and the related abnormal development of the embryos in the intergeneric crosses of radish (Raphanus sativus L.) ♀ with cabbage (Brassica oleracea L.) ♂. The weak development of ER, the occurence of starch grains in chloroplasts, the curious distribution of chloroplasts around the nuclei, and the earlier formation of cellular endosperm are some primary structure abnormalities of endosperm and they may indicate the poor development, low metabolic activities, and precocious growth in the hybrid endosperm. The endosperm abortion, which starts from chalazal end endosperm, comprises the damage of both structure and function of ER membrane, and the disintegration of nuclei and organelles, or even death. The hybrid embryos degenerated very early in 2-cell stage or even zygote stage in case the endosperm Aborted early. In case of endosperm late-aborted, the hybrid embryos grew for quite a long period of time but become slow down as the endosperm showed abnormal development and started to abort. As the results, the embryos were smaller, the embryo propers and the suspensors showed no growth in step with one another, and the embryo cells appeared structural abnormalities, and finally degenerated and aborted.