栓皮栎体细胞胚胎发生的细胞组织学观察

以栓皮栎未成熟合子胚为外植体,在添加0.25mg/L 2,4-D和0.5mg/L 6-BA的MS培养基上6周可诱导产生2种类型的胚性愈伤组织,一种表面具光泽、白色;另一种表面光滑湿润具光泽,色泽淡黄或无色透明。组织切片表明,胚性愈伤组织的细胞体积小,细胞核大,细胞质浓,细胞排列紧密;非胚性愈伤组织细胞的体积大,细胞核小,细胞质稀薄。胚性细胞团培养在不含激素的培养基上可诱导产生体细胞胚。体细胞胚直接起源于胚性细胞团表皮或近表皮的单细胞,经历与合子胚相似的球形胚、心形胚、鱼雷胚和子叶胚发育阶段。所有发育时期的体细胞胚的胚轴、子叶均产生次生体胚,它们起源于细胞质较浓的表皮单细胞。

Histological Observation of Somatic Embryogenesis from Cultured Embryos of Quercus variabilis BI.

Immature zygotic embryos of Quercus variabilis Bl. were excised and cultured on MS basal medium containing 0.25 mg/L 2,4-dichlorophenoxyace-tic acid and 0.5 mg/L 6-benzyl aminopurine. Callus was initiated from these embryos within 6 weeks. Two types of embryogenic calluses were formed: one was the white mucilaginous callus and the other was light yellow to translucent,glossy,mucilaginous. Histological examina-tion showed that the non-embryogenic cells derived from zygotic embryos were large in size,with small nuclei,thin cytoplasm,and the embryogenic cells were small in size,with large nuclei,thick cytoplasm and denser arrangement. Somatic embryos were induced from em-bryogenic masses (EMS) cultured on a medium not con-taining plant growth regulators (PGRs). The histologi-cal origin of somatic embryos was single epidermal or subepidermal cells. Somatic embryos displayed a stan-dard development pattern,from globular ones to heart-like and torpedo-shaped ones and finally to embryo with two cotyledons,which was similar to the development of zygotic embryo in vivo. Secondary proembryos were formed on the axis and cotyledon of existing embryos and originated from single,densely stained cells of the epidermis at all stages.