Embryological Studies on Facultative Apomixis in Apluda mutica (Gramineae)

水蔗草兼性无融合生殖胚胎学研究(英文)

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.

对水蔗草 (ApludamuticaL .)的生殖方式进行研究 ,结果表明水蔗草进行兼性无融合生殖。胚囊发育分为两种类型 ,即有性生殖的蓼型和无孢子生殖的大黍型。无融合生殖胚囊频率为 6 0 .74%。在大孢子母细胞发育至四分体后 ,珠孔端的 3个大孢子解体。合点端的大孢子未解体时 ,邻近大孢子的 1个珠心细胞开始特化 ,形成无融合生殖的原始细胞 ,由该原始细胞发育形成有 1个卵细胞、1个助细胞和 2个极核的四核胚囊。