γ射线辐照对大蒜和洋葱生长点细胞及超微结构的影响

电镜观察表明,γ射线2～30 krad辐照大蒜和洋葱,能造成生长点细胞及超微结构的不同程度损伤。如细胞外形畸变、细胞壁加厚、质壁分离、原生质破坏呈电子透明,核破碎,染色质变粗变短,微结构变形,甚至膜破裂等。其损伤程度随辐照剂量的增加而趋严重。不同微结构的抗辐照能力不同,其中液泡的辐射敏感性最强,核仁和线粒体最抗辐照。辐照后的细胞和超微结构一般在萌动期才表现出明显的形态损伤、细胞分裂受阻,因此抑制了大蒜和洋葱的发芽。

THE EFFECTS OF γ-RAY IRRADIATION ON THE CELLULAR AND SUBCELLULAR STRUCTURES OF APICAL MERISTEM IN GARLIC(Allium sativum) AND ONION (Allium cepal)

Electronic-microscopic study revealed that 2~30 krads of γ-ray irradiation to garlic and onion could cause various damages to cellular and subcellular structures of the shoot apical meristem.Among the various oganelles,the vacuoles showed the highest radio-sensitivity while mitochondria and nucleus seemed to be most resistant to irradiation.The irradiated cells did not show any visible structural damages untill the dormancy ended,suggesting that metabolism played an important role in the structural damages.The study also suggested that even after the irradiation which caused intensive subcellular structural damages,the tissues could survive.However,the potence of mitosis in the apex was lost,resulting in the inhibition of sprouting.