Differential sensitivity of chloroplasts in mesophyll and bundle sheath cells in maize, an NADP-malic enzyme-type C4 plant, to salinity stress
Differential sensitivity of chloroplasts in mesophyll and bundle sheath cells in maize, an NADP-malic enzyme-type C4 plant, to salinity stress
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DOI：
10.1626/pps.8.567
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发表时间：
2005-12-01
影响因子：
2.5
通讯作者：
Miyake, H
中科院分区：
文献类型：
--
作者：
Hasan, R;Ohnuki, Y;Miyake, H
以具有二型叶绿体的玉米为材料，研究了盐胁迫下叶绿体超微结构和叶绿素、Na、K含量的变化。在光照或黑暗条件下，用0、1、2或3%NaCl处理幼苗3或5天。在光照和黑暗条件下，盐处理植株的干重随着NaCl浓度的增加而降低。在光照条件下，第二叶叶绿素和钾含量随NaCl浓度的增加而降低，但在黑暗条件下不随NaCl浓度的增加而降低。在高盐浓度下，第二叶片的Na含量显着较高，在光和黑暗条件下。而在黑暗条件下，Na含量明显低于光照条件。高浓度NaCl（2%和3%）处理使叶绿体中的质体小泡体积增大，淀粉粒的数量和体积减小，叶绿体超微结构发生改变。在光照条件下，叶肉细胞（MC）叶绿体比维管束鞘细胞（BSC）叶绿体对盐胁迫的反应更为敏感。盐胁迫使MC叶绿体球形化，类囊体肿胀、结构紊乱，基粒厚度减小。BSC叶绿体受盐度的影响小于MC叶绿体。虽然叶绿体的大小和数量和大小的淀粉颗粒减少，有没有在BSC叶绿体类囊体的结构畸变。在黑暗条件下，盐对叶绿体结构的影响较小。盐胁迫下，虽然BSC叶绿体的被膜偶尔会受到破坏，但MC和BSC叶绿体中的类囊体仍得以保存。本研究表明，盐胁迫对叶绿体的损伤是光依赖性的，MC叶绿体比BSC叶绿体对盐胁迫更敏感。
The changes in chloroplast ultrastructure and the contents of chlorophyll, Na and K in response to salinity stress were investigated in leaves of maize, an NADP-malic enzyme-type C, plant species possessing dimorphic chloroplasts. The seedlings were treated with 0, 1, 2 or 3% NaCl for three or five days under a light or dark condition. In both light and dark conditions, the dry weight of salt-treated plants decreased as NaCl concentration increased. Chlorophyll and K contents of the second leaf blade decreased as NaCl concentration increased under the light condition but not under the dark condition. Na content of the second leaf blade was significantly higher at high NaCl concentrations under both light and dark conditions. However, Na content was much lower under the dark condition than light condition. Higher concentrations (2 and 3%) of NaCl significantly increased the size of plastoglobules, decreased the number and size of starch granules and altered the chloroplast ultrastructure. Under the light condition, mesophyll cell (MC) chloroplasts appeared more sensitive to the damaging effect of salinity than the bundle sheath cell (BSC) chloroplasts. MC chloroplasts became more globular in shape and showed swollen and disorganized thylakoids and reduced thickness of grana by salinity. BSC chloroplasts were less affected by salinity than MC chloroplasts. Although chloroplast size and number and size of starch granules were reduced, there was no structural distortion in the thylakoids of BSC chloroplasts. However, the thickness of grana was increased by salinity, Under the dark condition, the chloroplast structure was less affected by salinity. Though the envelope of BSC chloroplasts was occasionally damaged, the thylakoids in both MC and BSC chloroplasts were preserved under salinity stress. The present study suggests that the chloroplast damage caused by salinity is light-dependent and MC chloroplasts are more sensitive to salinity than BSC chloroplasts.