The biological effects during seed germination were investigated after the dry seeds of Stevia rebaudianum Bertoni were implanted with carbon ion beam of 75 keV and 10 14 ions/cm 2. The results showed that the germination rate of carbon ion implanted seeds was slightly higher than that of the control, but the survival rate of the treated seedlings, on the contrary, was lower than that of the control (P <0.02), while the height of the treated seedlings was significantly higher than that of the control (P <0.01). On the 4th day after germination, the leaf cell wall in the treated group was thick, some high electron-dense substance deposited in the enlarged plasmodesma; Cell membrane reased with high electron-dense granules deposited on it. The plasma membrane protruded towards cell wall, and the granules shifted via plasmodesma or deposited onto cell wall. These phenomena may be related to the conveyance of implanted ions across cell wall, or be related to the accumulation of callose. In addition, the implantation of carbon ions could increase the lamellae of the chloroplast and cause high development of the chloroplast which sometimes contained two plastid centers in an individual chloroplast. Also, the highly developed cristae, abundant mitochondria and typical crystalloid structure in microbody could be found. All these results indicated that the anabolic and catabolic activities in the seedlings implanted with carbon ions before germination were obviously more active than those in the controls.
注入碳离子对甜菊的生物学效应
沈明山 蒋先志 徐金森 陈亮 陈睦传*
（厦门大学细胞生物学及肿瘤细胞工程教育部重点实验室，厦门361005）
摘要：对甜菊 (Steviarebaudianum Bertoni)种子注入能量为 75keV、剂量为 10 14 /cm2 的碳离子 ,研究其种子萌发期产生的一系列生物学效应。注入碳离子的种子萌发率略高于对照组 ,但种苗的成活率比对照组低 (P <0 .0 2 )。运用假设检验法分析 ,结果表明注入离子的种子出苗株高显著高于对照组 (P <0 .0 1)。萌发 4d的处理组 ,叶片细胞壁增厚 ,胞间连丝扩大 ,内有高电子密度的物质沉积 ,细胞质膜皱折 ,膜上有高电子密度的沉积颗粒 ,质膜向细胞壁方向突起 ,质膜上的颗粒通过胞间连丝转移或沉积于细胞壁上。上述现象可能与注入离子的过壁运输有关 ,也可能与胼胝质的积累有关。此外 ,实验组植物的叶绿体发达 ,片层结构明显多于对照组 ,两个质体发生中心同时存在于同一个叶绿体内 ;线粒体丰富 ,内嵴发达 ;微体内可见典型的晶格排列结构。这些结果表明 ,离子注入种子以后 ,种子萌发期的合成代谢和呼吸代谢能力明显强于对照组
关键词： 甜菊；碳离子注入；细胞器；生物学效应
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