A cytological study on Apluda mutica L. revealed that this species was a facultative apomict with 60.74% of apomictic embryo sac formation. Its sexual reproduction exhibited the characteristics of polygonum_type embry...A cytological study on Apluda mutica L. revealed that this species was a facultative apomict with 60.74% of apomictic embryo sac formation. Its sexual reproduction exhibited the characteristics of polygonum_type embryo sac formation. After the 3 megaspores at the micropylar end had degenerated, leaving only the chalazal megaspore in the nucellus, a nucellar cell adjacent to the megaspore differentiated into an aposporous initial, which later developed into a panicum_type embryo sac. It was an aposporous 4_nucleate embryo sac without chromosome reduction and composed of an egg, a single synergid and a central cell with 2 polar nuclei. The chalazal megaspore degenerated before the onset of the division in the aposporous initial cell.展开更多
The breeding system of an endangered dioecious species, Woonyoungia septentrionalis (Dandy) Law, was studied in two natural populations, the Mulun population and the Dahuangni population, in Guangxi Province, China fr...The breeding system of an endangered dioecious species, Woonyoungia septentrionalis (Dandy) Law, was studied in two natural populations, the Mulun population and the Dahuangni population, in Guangxi Province, China from June 2001 to early September 2002. The female flowers from previously bagged buds were treated respectively with paper bags, net bags and hand pollination by comparing with natural pollination. The results showed that female flowers treated with paper bags, net bags, hand pollination, and natural pollination all set fruits and seeds, but there was great difference in their fruit set, seed set, pre-emergent reproductive success (PERS) and seed germination rate for two populations. In both populations, PERS of hand pollination and natural pollination were higher than those of paper bagged and net bagged treatments. Among them, PERS of hand pollination was the highest, and PERS of net bagged treatment was the lowest. Both sexual reproduction and apomixis occurred simultaneously in W septentrionalis and seeds from both sexual and apomixis could germinate into seedlings. Therefore, the breeding system of W septentrionalis belonged to facultative apomixis. The apomixis in Magnoliaceae was reported for the first time.展开更多
文摘A cytological study on Apluda mutica L. revealed that this species was a facultative apomict with 60.74% of apomictic embryo sac formation. Its sexual reproduction exhibited the characteristics of polygonum_type embryo sac formation. After the 3 megaspores at the micropylar end had degenerated, leaving only the chalazal megaspore in the nucellus, a nucellar cell adjacent to the megaspore differentiated into an aposporous initial, which later developed into a panicum_type embryo sac. It was an aposporous 4_nucleate embryo sac without chromosome reduction and composed of an egg, a single synergid and a central cell with 2 polar nuclei. The chalazal megaspore degenerated before the onset of the division in the aposporous initial cell.
文摘The breeding system of an endangered dioecious species, Woonyoungia septentrionalis (Dandy) Law, was studied in two natural populations, the Mulun population and the Dahuangni population, in Guangxi Province, China from June 2001 to early September 2002. The female flowers from previously bagged buds were treated respectively with paper bags, net bags and hand pollination by comparing with natural pollination. The results showed that female flowers treated with paper bags, net bags, hand pollination, and natural pollination all set fruits and seeds, but there was great difference in their fruit set, seed set, pre-emergent reproductive success (PERS) and seed germination rate for two populations. In both populations, PERS of hand pollination and natural pollination were higher than those of paper bagged and net bagged treatments. Among them, PERS of hand pollination was the highest, and PERS of net bagged treatment was the lowest. Both sexual reproduction and apomixis occurred simultaneously in W septentrionalis and seeds from both sexual and apomixis could germinate into seedlings. Therefore, the breeding system of W septentrionalis belonged to facultative apomixis. The apomixis in Magnoliaceae was reported for the first time.
