同步辐射(软X射线)对冬小麦的诱变效应及机理研究Ⅲ.辐照种子产生的自由基和辐照引起种胚DNA非按期合成的研究

MUTAGENIC EFFECTS AND MECHANISM OF WINTER WHEAT IRRADIATED BY SYNCHROTRON RADIATION(SOFT X\|RAY) Ⅲ FREE RADICALS AND UNSCHEDULED DNA SYNTHESIS OF IRRADIATED SEEDS

应用电子自旋 (ESR)波谱术研究了同步辐射辐照种子产生的自由基及其与辐射损伤之间的关系。结果表明 ,同步辐射辐照的种子产生了大量的自由基 ,其种类、性质不同于γ射线 ,短寿命自由基 (小于 48h)产额高于γ射线 ,长寿命自由基 (大于48h)的稳定性大于γ射线。同步辐射自由基产额与辐照剂量呈线性关系。用3H TdR掺入法研究了受辐照种胚萌发早期DNA的合成动态 ,结果表明 ,同步辐射能够引起种胚DNA的损伤修复合成 ,其特点不同于γ射线。原冬 6号和北京41 1品种的DNA修复合成出现在种胚吸水后第一个正常的DNA合成峰之前 ,京冬8号品种出现在第一个小峰之后和

Free radicals of irradiated seeds were measured at room temperature by ESR spectrum technique. Experimental results showed that the radical's concentration in seeds increased continuously with the SR's doses, yet after γ ray's reaching a maximum they declined. The yields of short\|life radical(<48h) and the stability of long\|life radical by SR were greater than that by γ ray.\;With the method of 3H\|TdR incorporation, the changes of DNA synthesis in the early period of wheat seeds germination by SR were studied. The results showed that SR was able to induce an unscheduled DNA synthesis (UDS) in seed embryos of wheat, furthermore, a special trend of UDS. The level of the normal DNA synthesis decreased with the increase of the UDS in the irradiated wheat seed embryos. The feature and the 3H\|TdR incorporation of the UDS were not equal to that of in three varieties.