NaCl和Na2SO4胁迫下两种刺槐叶肉细胞叶绿体超微结构

二倍体刺槐(diploid Robinia pseudoacacia)是我国水土保持林的先锋树种,具有较强的适应性和抗逆性,对改善生态环境、防治水土流失、调节水文状况有重要作用。四倍体刺槐(tetraploid Robinia pseudoacacia)是二倍体刺槐的加倍品种,也称多倍体刺槐,由韩国引进,具有速生、耐盐碱、耐干旱和耐烟尘等特点。目前,关于四倍体刺槐的研究,主要集中于栽培技术和繁殖技术方面,而关于四倍体刺槐叶片超微结构与其耐盐性的关系尚缺乏报道。比较了二倍体刺槐和四倍体刺槐在NaCl和Na₂SO₄胁迫下,叶片叶绿体超微结构的变化特点,一方面可以对二者的耐盐性进行鉴定,同时也可以探讨不同盐分胁迫条件下的作用机制。利用NaCl和Na₂SO₄进行20d的盐胁迫处理,观察叶绿体超微结构的变化特点,发现:NaCl处理前,二者叶肉细胞叶绿体为梭形、形态饱满、结构完整,NaCl处理后10d时,二倍体刺槐的叶绿体出现变形、膜模糊、基粒片层松散、类囊体解体、脂质球增多等现象,NaCl处理后20d时,叶绿体肿胀、变形,基粒片层断裂,膜系统解体。Na₂SO₄处理后10d时,二倍体刺槐的叶绿体肿胀,膜模糊,基粒片层松散、类囊体解体,Na₂SO₄盐胁迫处理后20d时,膜系统全部解体,结构破坏更为严重。总体来说,四倍体刺槐在盐胁迫后叶绿体结构变化不明显,只是在Na₂SO₄处理20d时,四倍体刺槐的叶绿体出现中空、基粒片层松散、膜边缘模糊现象。在处理前,两种刺槐的叶绿体均紧贴细胞壁,分布于细胞壁边缘。在NaCl处理后10d时,二倍体刺槐的叶绿体仍呈有序排列,紧贴细胞壁,但在处理后20d时,大部分叶绿体脱离细胞壁,呈随机分布。在Na₂SO₄处理后10d时,二倍体刺槐部分叶绿体脱离细胞壁,位于细胞中央。在Na₂SO₄处理后20d时,二倍体刺槐叶绿体大部分与细胞壁脱离。四倍体刺槐在两种盐胁迫处理前后叶绿体的排列变化不明显,均分布于细胞壁边缘,紧贴细胞壁。所以在盐胁迫下,耐盐植物叶片的叶绿体表现为结构完整,基粒片层清晰,类囊体结构完整,而不耐盐植物则表现为叶绿体超微结构松散、变形,基粒片层模糊,破坏严重时基粒片层扭曲,叶绿体解体,失去完整结构。

The ultrastructure of chloroplast in mesophyll cell on two robinias under NaCl and Na2SO4 stress

The diploid black locust (diploid Robinia pseudoacacia) is a pioneer species of China's soil and water conservation forest, has strong adaptability and resistance and plays an important role in improving the ecological environment, preventing soil erosion and regulating hydrological conditions. The tetraploid black locust, also known as the polyploid black locust, is a double species of the diploid black locust. It was introduced from South Korea, with fast-growing, saline-alkali tolerant, drought-tolerant, dust-resistant and other characteristics. At present, studies on the tetraploid black locust focus mainly on cultivation and breeding techniques, however, the relationship between the ultrastructure of its leaves and its salt tolerance is still a lack of coverage. This study compared the changes in the leaf chloroplast ultrastructures of the diploid and tetraploid black locust under NaCl and Na₂SO₄ stress, which can not only identify their salt tolerance but also explore the function mechnism of salt stress to different plants.The ultramicrostructure of the chloroplast in the tetraploiddiploid black locust was observed under NaCl and Na₂SO₄ stress during 20 d. Before NaCl treatment, its chloroplast appeared spindle in shape, full in form and complete in structure. After NaCl treatment for 10 d, the chloroplast of the diploid black locust showed distortion, ambiguity in membrane, loose in grana lamella, disintegration in thylakoid, increases in lipid ball and so on. After NaCl stress for 20 d, the chloroplast of the diploid black locust displayed swelling and distortion, fracture in grana lamella and disintegration in membrane system. After Na₂SO₄ stress for 10 d, the chloroplast of the diploid black locust exhibited swelling, ambiguity in membrane, loose in grana lamella, disintegration in thylakoid. After Na₂SO₄ stress for 20 d, all membrane systems of the chloroplast in the diploid black locust were disintegrated and its chloroplast structures were damaged more seriously. On the whole, the ultramicrostructure of chloroplast of tetraploid black locust after salt stress had no obvious changes, only after Na₂SO₄ stress for 20 d, its chloroplast appeare hollow, loose in grana lamella and ambiguity in membrane edge.Before salt stress, the chloroplasts in two kinds of black locust were close to the cell wall and were distributed at the edge of the cell wall. After NaCl stress for 10 d, The chloroplasts of the diploid black locust were still in orderly rows and close to the cell wall, however, after NaCl stress for 20 d, most of the chloroplasts were out of the cell wall and were randomly distributed. After Na₂SO₄ stress for 10 d, part of the chloroplasts in the diploid black locust were breaked away from the cell wall and were located in the middle of it. After Na₂SO₄ stress for 20 d, most of the chloroplasts were out of the cell wall. Before and after two kinds of salt treatment, the chloroplasts in tetraploid black locust had no obvious changes in arrangement, were distributed at the edge of the cell wall and were close to it. Therefore, under salt stress, the chloroplast ultrastructure of salt-tolerant plants appeared intact, clear in grana lamellae and complete in thylakoid. The chloroplast ultrastructure of salt-intolerant plants displayed loose, deformation, fuzzy in grana lamellae, when these plants were severely damaged, their grana lamellaes were distorted, their chloroplasts were disintegrated and out of intact structures.