摘要
黑松(Pinus thunbergii Parl.)小孢子发生在三月上、中旬,三月下旬至四月上旬为花粉发育期,散粉时花粉为四细胞型。减数分裂后期Ⅰ、Ⅱ淀粉粒聚集于赤道区。花粉分裂前,细胞质浓缩至远极面,核由松散结构转变为紧密的球状结构。胼胝质最初出现在紧靠母细胞壁的内侧,然后分别出现在后期Ⅰ、Ⅱ的赤道区紧靠母细胞壁。有时,减数分裂的后期Ⅰ、Ⅱ不形成胼胝质或胼胝质发育不完全,在子核之间不产生细胞壁。黑松具单、三个或四个气囊的异型花粉。
The microsporogenesis in Pinus thunbergii occurs in early to middle March,and the deve- lopment of pollen in late March to early April.A mature pollen grain consists of four cells. The starch grains aggregate in the equators during meiosis Ⅰ to Ⅱ.The callose materials appear first in inner side of the wall of meiocyte and then in the equator Sometimes the 3-or 4-sac- care pollen grains have been found.In the ontogeny of pollen in Pinus thunbergii following events are noteworthy.(1)During meiosis the equatorial aggregation of starch grains in me- iocyte becomes conspicuous.(2)During formation of tetrad the callose wall appears in regular activity.It is noteworthy that there is itself feature for the accumulation of callose in Pinus thunbergii.After formation of prothallial cells the callose appears mainly in the area between body and saccus.So the prominent symmetry of distribution of callose occurs in the pollen grains.But almost no callose accumulation takes place in tenuity in distal face of pollen grain.On the contrary,there are certain callose accumulation around the prothallial cells in the proximal face,forming the polar distribution of callose in pollen grains.
关键词
黑松
个体发育
花粉
Callose
Microsporogenesis
Ontogeny
Pinus thunbergii
Pollen
