^(60)Co-γ辐照对三七叶片叶绿体和线粒体超微结构的影响

Effect of ^(60)Co-γ Irradiation on the Ultrastructure of Chloroplast and Mitochondrion of Panax notoginseng Leaves

应用透射电子显微镜观察了经不同剂量60Co-γ射线辐照的三七叶片叶绿体和线粒体超微结构,研究了60Co-γ辐照对三七叶片叶绿体和线粒体超微结构的影响,旨在为三七辐照育种提供理论依据。结果表明:(1)未受辐照情况下,三七叶片细胞形态规则,细胞内叶绿体数量多,基粒片层、基质片层多且有序,光合作用能力强;线粒体形态饱满,双层膜完整,管状内嵴清晰可见,基质浓厚。(2)当辐照剂量为10 Gy时,叶绿体和线粒体超微结构发生变化,但受影响程度较轻。叶绿体被膜轻微破坏,内部基粒片层和基质片层结构基本不受影响,淀粉粒增大增多;多数线粒体结构完整,数量略微增加,可以看出,线粒体对60Co-γ射线辐照的耐受性比叶绿体强。(3)随着辐照剂量的增加,叶绿体和线粒体超微结构受损伤程度随之增强。当辐照剂量达到40 Gy时,叶绿体大量解体,空泡大量出现,并连成大的空洞,结果必然影响叶绿素含量和光反应的正常进行,从而显著减弱光合作用强度;部分线粒体内部降解严重甚至已完全空泡化,线粒体数目明显减少,线粒体结构和功能遭到不可逆的严重损伤,细胞衰老严重。上述结果表明,60Co-γ射线辐照对三七叶片叶绿体和线粒体超微结构产生不同程度的损伤,但适当的辐照可增加线粒体数量。以上结论可以为不同目的的三七育种提供理论依据,并为选择最适辐照诱变育种剂量提供理论参考。

The ultrastructure of ^60Co-γ irradiation with different doses on chloroplast and mitochondrion of Panax notoginseng was observed by transmission electron microscop（TEM） and the effects of ^60Co-γirradiation on the ultrastructure were studied,aimed at providing theoretical basis for notoginseg irraditionbreeding.The results showed that：（1） without irradiation,the notoginseng leaf cells＇ shapes were normal andhad many chloroplasts,there were many orderly grana lamellas and stroma lamellas,which led to strongphotosynthesis capacity; mitochondria with complete double membrances were full of strong matrix and tubularcristae could be clearly observed;（2） when the irradiaion dose was 10 Gy,the ultrastructure of chloroplast andmitochondria changed,while they were affected to a lesser degree; the chloroplast membranes were damagedslightly,the structures of internal grana lamellas and stroma lamellas were not affected basically and there had more and bigger starch grains; the structures of most mitochondria were integrity and the number had slightlyincreased,which showed that the mitochondria had better tolerance to ^60Co-γ irradiation than chloroplasts;（3）the study also indicated that the damage degree of the ultrastructure of chloroplast and mitochondria becamemore serious with the increase of irradiation dose.When the irradiation dose was 40 Gy,a large number ofchloroplasts disintegrated,vacuoles appeared in great numbers and were connected into a big holes,the resultsinevitably affected chlorophyll content and light reaction,thereby significantly weakened the intensity ofphotosynthesis; internal degradations of some mitochondria were serious and some even had completelyvacuolization,mitochondrial number was significantly reduced,meanwhile,the structure and function ofmitochondria were severely damaged irreversibly with serious cell senescence.It might be concluded that therewere different damages in the ultrastructure of chloroplast and mitochondrion of Panax notoginseng leaves by ^60Co-γ irradiation,but proper radiation could increase the number of mitochondria.The above conclusionscould provide theoretical basis for notoginseng breeding of different purposes and theoretical reference forchoosing the most appropriate irradiation dose of mutation breeding.