UV-B辐射对几种木本植物幼苗生长和叶绿体超微结构的影响

Effects of UV-B Radiation on Seedling Growth and Chloroplast Ultrastructure Changes in Some Woody Plants

在实验室条件下研究了UV-B辐射对广东省南亚热带森林中5种木本植物九节、鸭脚木、猴耳环、半枫荷、山乌桕和绿化树种大叶合欢的幼苗形态和细胞超微结构,特别是叶绿体超微结构的影响。结果表明,UV-B辐射抑制幼苗主根伸长和减少侧根数,抑制茎伸长,减少叶数和叶面积。UV-B辐射破坏叶片细胞膜结构,特别是叶绿体膜结构,但不同种受影响的程度不同,所表现的症状也不完全相同,鸭脚木的质膜收缩,导致质壁分离;鸭脚木、半枫荷和猴耳环的叶绿体膨胀,前二者的甚至破裂;鸭脚木和半枫荷的类囊体膨胀粘连;猴耳环的线粒体出现空泡化;半枫荷和猴耳环的叶绿体内大的淀粉粒增多;鸭脚木和山乌桕的叶绿体内或膜上黑色颗粒增多,鸭脚木的线粒体膜上也出现黑色颗粒。

A study was conducted to determine the effects of UV-B on seedling growth and chloroplast ultrastructure of Psychotria rubra, Schefflera octophylla, Archidendron clypearia, Pterospermum heterophyllum, Sapium discolor and Albizia lebbeck. The seeds of these species were collected from Nature Reserves in Guangdong, and the seedlings were grown in growth cabinets programmed for a 28/20℃ light/dark temperature regime and a 12 h photoperiod. The 15-day-old seedlings were exposed to visible light (23μmol m2 s^(-1)) supplemented with7.2 kJ m2 d^(-1) or 14.4 kJ m2 d^(-1), or without UV-B radiation (control) for 30 and 60 days Results demonstrated that UV-B radiation inhibited the growth of main roots and stems, decreased the number of lateral roots and leaf number as well as leaf area. UV-B radiation damaged membrane of leaf cells, particularly the structure of chloroplast membrane. Affected symptoms varied with plant species. Under UV-B radiation, the plasma membrane in Schefflera octophylla was contracted and corrugated, and separated from cell wall. Chloroplast in S. octophylla and Pterospermum heterophyllum was dilated and even broken, the thylakoid dilated and adhered. In Archidendron clypearia the mitochondria appeared to be cavitate. Starch grains in chloroplast in A. clypearia and Pterospermum heterophylla were increased, and the black particles in chloroplast in Schefflera octophylla and Sapium discolor were also increased, and appeared on mitochondrial membrane of S. octophylla.