Abstract: In order to find out the effect of ⁶⁰Co-γ radiation on the leaves of Bromus inermis under drought,and to provide theoretical basis for Bromus inermis breeding under drought,the leaf cells of Bromus inermis,of which seeds exposed to ⁶⁰Co-γ radiation under drought stress were observed by transmission electron microscope,to compare the impacts of radiation on the morphological and ultrastructural structure of leaf cells,chloroplasts and mitochondria. The results showed that the cell morphology of Bromus inermis leaves was regular with plenty and orderly basal lamellae and stromal lamellae in chloroplast without irradiation and PEG stress. The membrane of mitochondria in the leaves of Bromus inermis was intact with clear cristae and the thick matrix. Under the stress of 10%PEG,the cells in the leaves,from seeds radiated by 50 Gy,distorted seriously,with largely irregular cell morphology,uneven cell wall thickness,invaginated plasmalemma and slight separation of cytoplasm and cell wall. When the radiation dose was 50 Gy under 10% and 20%PEG stress,the morphology and ultrastructure of chloroplast and mitochondrion were slightly affected. The damage degree of chloroplast and mitochondrial ultrastructure increased with the increasing of drought stress and irradiation dose. When the irradiation dose was 200 Gy under 20%PEG stress,the chloroplast membrane of leaf cells was damaged to some extent,the arrangement of basal lamellae tended to disorderly,some basal lamellae were not clear,while the structure of stromal thylakoid lamellae was clear,and a small amount of starch granules could be seen. The mitochondrial membrane of leaf cells was damaged seriously,with declined internal crista,irregular arrangement and shallow matrix. The ultrastructures of chloroplasts and mitochondria of Bromus inermis leaves were damaged to varying degrees by ⁶⁰Co-γ irradiation. In the drought resistance breeding of Bromus inermis with ⁶⁰Co-γ radiation,the low dose of 50 Gy combined with 20%PEG simulated drought stress could be selected to screen the drought resistant mutants.

Key words: Bromus inermis, PEG stress, ⁶⁰Co-gamma radiation, Leaf structure

摘要： 为明确⁶⁰Co-γ射线对干旱条件下无芒雀麦（Bromus inermis）叶片的影响，从而为无芒雀麦利用辐射进行抗旱育种提供理论依据，本试验应用透射电镜观察聚乙二醇（Polyethylene glycol，PEG）模拟干旱胁迫下的⁶⁰Co-γ射线辐射无芒雀麦的叶片细胞，比较辐射对无芒雀麦叶片细胞、叶绿体、线粒体的形态和超微结构的影响。试验结果表明：未受辐射和PEG胁迫的无芒雀麦叶片细胞形态规则，叶绿体基粒片层和基质片层多且有序，线粒体膜完整，内嵴清晰，基质浓厚。10% PEG胁迫50 Gy辐射处理组叶片细胞扭曲最严重，形态不规则，细胞壁厚度不均，质膜内陷，有轻微质壁分离。10%和20% PEG胁迫下辐射剂量为50 Gy时，叶绿体和线粒体形态和超微结构受影响程度较轻，随着干旱胁迫强度和辐照剂量的增加，叶绿体和线粒体超微结构受损伤程度增强；20% PEG胁迫下辐射剂量为200 Gy时，叶绿体膜有不同程度破损，基粒片层排列的紊乱性增加，部分基粒片层不清晰，基质类囊体片层结构清晰，可见少量淀粉粒；线粒体膜破损比较严重，内嵴减少，排列不规则，基质较浅。可见，不同⁶⁰Co-γ射线辐射剂量可对无芒雀麦叶片叶绿体和线粒体超微结构产生不同程度的影响，在利用⁶⁰Co-γ射线辐射进行无芒雀麦耐旱性育种时，可选择50 Gy低辐射剂量结合20% PEG模拟干旱胁迫进行抗旱性突变体的筛选。

关键词: 无芒雀麦, PEG胁迫, ⁶⁰Co-γ辐射, 叶片结构