银杏叶片生长和衰老过程中叶绿体超微结构的变化

摘要

Changes in ultra-structure in chloroplasts of 10-year-old seeded ginkgo ( Ginkgo biloba L. ) leaves during expansion and senescence were studied in the field under natural environmental condition. The results showed that the chloroplast ultra-structure changed obviously during leaf expansion, grana thylakoids were increasingly richer, lamellar structure was more developed and neatly arranged, and the photosynthetic apparatus was gradually improved. The chloroplast ultra-structure changed significantly during leaf senescence. As the leaf senesced, the volume of chloroplasts became swollen, the envelope membranes became disrupted, the inclusions became reduced and the granal thylakoids became loose. The chloroplasts changed from ellipses or ship-like shapes to the irregular circles, had damaged in membranes and fewer grana with loose stacks of thylakoids and more and larger osmiophilic granules. With the leaf senescence, the whole structure of chloroplasts became disorganized, the thylakoid membranes became disrupted, the stroma in chloroplasts almost lost, and finally, the chloroplast was completely disintegrated.%本研究以大田栽培的十年生雄性银杏植株为试材，研究了自然条件下叶片生长和衰老过程中叶肉细胞叶绿体超微结构的变化。结果表明：叶片生长过程中叶肉细胞叶绿体的超微结构有着明显改变，基粒类囊体逐渐丰富，片层结构更为发达，排列更加整齐，光合器官逐步完善。叶片衰老过程中其叶肉细胞叶绿体的超微结构也发生了显著变化，随着叶片的衰老，叶绿体内基质片层变得松散，叶绿体体积逐渐膨大，形态以不正常的圆形为主，类囊体膜的结构遭到破坏，基粒类囊体膜逐渐松散或消融，基质逐渐散失，嗜锇滴变大并逐渐增多。随着衰老的加剧，叶绿体开始解体，被膜破裂，内含物减少，内部结构出现破坏，最后叶绿体完全解体。