X射线对根尖细胞分裂和分化的作用

EFFECTS OF X-IRRADIATION ON CELL DIVISION AND CELL DIFFERENTIATION OF ROOT TIPS

用30—70GyX射线照射小麦幼苗(浸种后5天)后发现根毛区到根尖的距离缩短,根毛变密,根毛长度为对照的2—3倍。照射后2—3天就可看到该现象。根毛着生处到根尖的距离随剂量增加而减少,甚至根尖全为根毛所复盖,另外还看到有分叉的根毛。根尖纵切片表明根尖分生区随剂量增加而缩小,分生区后接着就出现输导组织。玉米和黄瓜也有类似现象。这现象说明根细胞的分裂过程对射线很敏感,而分化过程则相当耐辐射,细胞分裂停止后立即转向细胞分化过程。

When wheat seedlings were irradiated with various dosage of 30-70 Gy X-rays, the distance between root hair zone and root tip was shortened, the root hairs became denser and its length was increased to 2—3 times of the control. These phenomena were observed on 2nd or 3rd day after irradiation. The distance between root hair zone and root tip was decreased with increasing radiation dosage and the whole root tip was covered by root hairs treated with higher dosage. The bifurcate root hairs of wheat seedlings irradiated were also observed. It was observed from the longitudinal sections of wheat root tips the number of meristematic cells decreased with increasing of radiation dosage and the vessels appeared near the meristem zone of root tip of wheat seed ling irradiated with 60 Gy X-rays. Similar phenomena were also observed in Zea mays and Cucumis sativus. These phenomena showed that cell division process was very sensitive to radiation. However, cell differentiation process was very tolerant to radiation. When the cell division was inhibited by radiation, the cells differentiated immediatly.