Na_2CO_3胁迫对星星草叶肉细胞超微结构的影响

Effects of Na_2CO_3 stress on the ultrastructure of mesophyll cells in Puccinellia tenuiflora

利用透射电镜技术对Na2CO3胁迫下星星草叶肉细胞超微结构进行了观察。结果表明:未胁迫的叶肉细胞排列疏松,各种细胞器结构完整,叶绿体含少量淀粉粒和脂质球。轻度盐胁迫(2g/L,4g/LNa2CO3)对叶肉细胞超微结构影响较小。中度盐胁迫(6g/L,8g/LNa2CO3)引起叶肉细胞超微结构的变化,叶绿体类囊体肿胀,基粒紊乱,不含淀粉粒,脂质球数量增加,叶绿体由原来的梭形或椭球形变成圆球状;部分线粒体嵴消失,出现晶体结构;中央大液泡破裂;核逐渐降解。高度盐胁迫(10g/L,12g/LNa2CO3)下,叶绿体片层结构消失,脂质球数量增加,体积变大,被大量的膜片层所包围,叶绿体内、外膜消失,叶肉细胞中看不到叶绿体的存在;膜片层包围线粒体;叶肉细胞中可见大量的泡状结构和膜片层,叶肉细胞死亡。上述结果表明,细胞器特别是叶绿体膜结构的破坏与盐胁迫叶肉细胞最终死亡密切相关。

The ultrastructural changes of mesophyll cells in Puccinellia tenuiflora occured during suffering from Na3CO3 stress, were observed using transmission electron microscopy. The results showed that under the normal condition, mesophyll cells arranged loosely, various organelles were morphologically integrated, some starch grains and electron-dense globules （plastoglobulus） were presented in chloroplasts. No alteration of uhrastructure was found by mild Na2 CO3 （2g/L, 4g/L Na2CO3 ） stress. While under moderate Na2 CO3 （6g/L, 8g/L Na2 CO3 ） stress, the most conspicuous change was the swelling of the thylakoid membranes, disorganization of grana, a marked increase in the number of plastoglobulus, and no starch grains in chloroplasts with the shape of spheroid. The breakdowm of cristae and appearance of certain crystal structure were observed in some mitochondria. The ultrastructure of cell nuclei and vacuole became degraded. Under severe Na2CO3 （ 10g/L, 12g/L Na2CO3 ） stress, the chloroplast membrane and the lamellar structure were almost disorganized with a mass of plastoglobulus, mitochondria became disintegrated, the whole mesophyll cells was full of vesicular multicycle-like membrane structures and degraded. These results indicated that the injury in membrane structure of various organelles, especially chloroplast, was closely associated with the eventual death of mesophyll cells.