太白红杉雌配子体的形成、受精、胚胎发育及其系统学意义(英文)

Female gametogeny, fertilization, embryogeny of Larix chinensis and it's systematic significance

太白红杉 LarixchinensisBeissn 雌球花于7月中下旬开始分化,9月上旬至9月中旬形成大孢子母细胞,10月中旬,大孢子母细胞进入休眠期.翌年4月底至5月初解除休眠,大孢子母细胞进行减数分裂,于5月10日左右形成直列四分体,随后珠孔端的3个大孢子退化,合点端的1个大孢子进一步发育.成熟卵细胞于7月初受精;花粉管将内含物释放入卵细胞后在尾部形成浓密物质沉淀;受精后,合子被染色较深的新细胞质所包围,并发现存在多精入卵的现象.合子经过两次连续有丝分裂,产生4个游离核后伴随新细胞质一起移至合点端,接着同时进行一次有丝分裂产生8个核,并分成上下两层后形成细胞壁,但上层细胞顶部不形成细胞壁.原胚发育属于松型.在幼胚阶段,我们发现部分胚珠发育异常,其雌配子体有的变为半透明状,有的则干瘪萎缩.太白红杉具简单多胚和莲座胚.9月中旬,成熟胚形成,成熟胚具5～6枚子叶.太白红杉从雌球花花芽分化到胚胎成熟历时14个月.

It takes 14 months from the differentiation of female strobilus to the formation of the mature embryo of Larix chinensis Beissn. The female strobilus bud initiates by mid-July. Following the formation of megasporocyte in September to October, there is an about 7-month period of winter dormancy before megasporocyte begins its meiosis in April-May of the following year. Linear tetrad appears around mid-May, and the three megaspores toward the micropyle end of the ovules degenerate, while the megaspore at the chalazal end develops later on. Each seminiferous scale of the female strobilus bears two inverted ovules which are fertilized in early July. A dense deposit appears around the remnant of pollen tube after its content released into the egg cell. After fertilization, the zygote nucleus is surrounded by neocytoplasm, and sometimes more than one pollen tubes release their contents into the egg. The development process of the proembryo is pinoid. Simple polyembryony occurs frequently and rosette embryo occurs occasionally. The mature embryo with 5~6 cotyledons appears in mid-September.