Studies on Megasporogenesis and the Development of Female Gametophytes in Diploid and Autotetraploid Broccoli

摘要

Traditional paraffin sectioning was used to observe the development of megaspore and female gametophytes of diploid and autotetraploid broccoli. The results indicated that the ovary has two carpels, two locular, parietal placenta and one series of ovules per locule. The development of the embryo sac was of the polygonum type. The mature ovules were campylotropous with dual-integuments and crassinu-cellate. The single archesporial cell functions directly as megaspore mother cell. The later undergoes meiotic divisions and develops into a linear tetrad. The megaspore at the chalazal end became a functional megaspore. There were eight nuclei in the mature embryo sac. Embryo sac development of antotetraploid broccoli was normal and similar with that of diploid. A total of 53.1 and 50.5% of the ovules can develop into mature embryo sac in the diploid and autotetraploid broccoli, respectively.