大叶杨的受精作用和胚胎发育

FERTILIZATION AND EMBRYO DEVELOPMENT OF POPULUS LASIOCARPA OLIV.

用细胞化学方法研究了大叶杨(Populus lasiocarpa Oliv.)的受精作用和胚胎发育。结果表明:柱头在授粉期有蛋白质和多糖性质的分泌物。花粉在授粉后6小时大量萌发。授粉后6天开始出现双受精作用。次生核受精完成较卵核受精完成为早,精卵融合为有丝分裂前型。受精作用消耗大量淀粉粒。核型胚乳于授粉后开始细胞化。胚乳主要成分为蛋白质,游离核形成后不出现淀粉粒。胚乳在胚的发育中被吸收。休眠期的合子经历液泡消失、合子皱缩、液泡再出现、合子伸长等极性化过程。胚胎发生类型为茄型。授粉后44天,胚相继发育成熟。成熟胚直立,具2枚相互包裹的子叶。根冠原中具类根冠柱结构。

The double fertilization and embryo development of P.lasiocarpa were studied using cy- tcchemical method for DNA,RNA,polysaccharides and proteins.Stigmas were covered by secretion stained positively with PAS and mercuric bromphenol blue at receptive stage.The pollen grains germinated on the stigma in large quantities 6 hours after pollination.Fertiliza- tion started at the 6th days after pollination.The sperm nucleus fused with the secondary nuc- leus faster than the sperm nucleus with the egg nucleus.The syngamy belonged to peremitotic type.A great deal of starch grains in the embryo sac disappeared during fertilization.The endosperm was nuclear type and becomed a cel 31 days after pollination.The endosperm was characterized by a dense cytoplasm rich in protein.No discrete starch grains were observed in endosperm.Afterwards,the endosperm was consumed by the developing embryo,thus the mature seeds were non-endospermous The zygote was dormant for 6—8 days.During the dormency,many striking changes took place,and then,the zygotes showed more pronounced polarity.These changes included the shinkage of the large vacuole,the reduced size,the reap- pearance of large vacuole,the enlarging of the size.The embryogenesis conformed to the So- lanad type.The ovules matured into seeds successively 44 days after pollination.The mature embryo was straight.Two cotyledons folded each other.