摘要
本文报道了玉米花粉愈伤组织形成胚状体的条件及其细胞形态学观察的结果。培养基中加入酪朊水解物500毫克/升和2,4-D2毫克/升对胚状体的形成是有利的。切片观察表明:多数胚状体来源于愈伤组织表层细胞,也有少数产生于愈伤组织的里层。胚状体的发育顺序和合子胚大体相似.胚状体的原始细胞表现出原生质较浓、核较大等特点。原始细胞第一次有丝分裂产生二个子细胞——基细胞和顶端细胞,基细胞不分裂或进行几次分裂形成胚柄,顶端细胞第一次进行纵的分裂,然后由这二个细胞进行纵横分裂形成胚体。胚状体具有一个子叶、二个子叶或多子叶等各种形状。愈伤组织产生胚状体是不同步的,因而在同一块愈伤组织中可以见到不同发育时期的胚状体。
Observations on the callus sections showed that most embryoids were pro- duced from surface layer cells of the callus and a few embryoids from inside layers of the callus.The initial cell of the embryoids possessed denser protoplasm and larger nucleus than the others cells did.The developmental sequence of the initial cell was similar to that of the zygotic embryos.First division gave rise to two daughter cells,the basal cell and termi- nal cell.The basal cell was able to divide or not divide again and changed into the suspen- sor,The terminal cell first divided longitudinally and then transversely into four cells.As the four cells further divided the embryo was formed properly.The embryoids possessed mono-,di-or polycotyledons.The production of the embryoids from a callus was not syn- chronous.So embryoids of different development stages could be found on the same callus.
