Authors：Feng Zou, Su-Juan Guo, Peng Xie, Wen-Jun Lv, Huan Xiong, Guang-Hui Li

Year：2013

Key words：Castanea mollissima, megasporogenesis, microsporogenesis, male gametophyte, female gametophyte.

　Chinese chestnut (Castanea mollissima Blume.) is a widely distributed fruit tree and well known for its ecological and economic value. In order to evaluate obstacles to sexual reproduction in C. mollissima, microsporogenesis, megasporogenesis, and development of the male and female gametophytes of the C. mollissima ‘Yanshanzaofeng’ cultivar were examined by a paraffin section technique and scanning electron microscopy. Results showed that the anther wall was of the basic type and consisted of an epidermis, endothecium, middle layers, and tapetum. The tapetum was of the glandular type. Cytokinesis during meiosis of the microspore mother cell was of the simultaneous type, tetrads were tetrahedral, pollen grains were the 2-cell type, and development of the embryo sac was of the Polygonum type. In total, 16~18 ovules were found in the ovary axis, and the ovules were anatropous, bitegmic, and crassinucellate. Before fertilization, the 2 polar nuclei fused into a secondary nucleus. The mature embryo sac was made up of 7 cells. Abnormal embryo sacs or abortive ovules were observed in the ovary. The abortive ovules are likely the cause of the low seed set in C. mollissima ‘Yanshanzaofeng’.