用X或Υ射线照射诱发非S期DNA合成,现已视为修复复制的一种证据。研究由细胞周期中合成前期细胞组成的萌发种子胚以及无蔗糖培养基上人工同步培养的根尖分生组织片断证明,后者的细胞是不进入DNA合成期的。观察正常生长并进行非同步分裂的分生组织细胞的非S期合成还存在困难。非S期DNA合成被正常复制和某些分生组织细胞的多倍化现象掩盖了。例如,Wolff和Scott计算了 Induction of non-S-phase DNA synthesis with X or Υ-ray irradiation is now considered as evidence of repair replication. The study demonstrated that germ-seed embryos composed of presynthesized cells in the cell cycle and apical meristematic sections of artificial synchronous cultures on sucrose-free medium proved that the latter cells did not enter the stage of DNA synthesis. It is difficult to observe the non-S-phase synthesis of meristematic cells that grow normally and perform asynchronously. Non-S-phase DNA synthesis is masked by normal replication and polyploidization of some meristematic cells. For example, Wolff and Scott calculated