Consequences of salt stress on conductance to CO2 diffusion, Rubisco characteristics and anatomy of spinach leaves
Consequences of salt stress on conductance to CO2 diffusion, Rubisco characteristics and anatomy of spinach leaves
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DOI：
10.1071/pp97161
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发表时间：
1998-01-01
期刊：
影响因子：
--
通讯作者：
Loreto, F
中科院分区：
文献类型：
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作者：
Delfine, S;Alvino, A;Loreto, F
菠菜 (Spinacia oleracea L.) 叶子在用含有 1% (w/v) NaCl 的水灌溉 20 天后，其气孔和叶肉中的 CO2 扩散传导性均较低。盐胁迫下叶片的叶肉解剖结构发生变化，这可能是叶肉电导率降低的原因。核酮糖 1,5-二磷酸羧化酶/加氧酶的体外活性和含量不受暴露于盐度长达 20 天的影响，但当叶片暴露于盐胁迫超过 20 天时，活性和含量会降低。盐的积累还导致钙和镁的下降，这可能分别降低膜稳定性和叶绿素含量。叶绿素荧光测量表明，20天的盐胁迫并没有直接影响光化学。我们得出的结论是，盐度主要通过减少二氧化碳向叶绿体的扩散来减少光合作用，既通过气孔关闭，又通过叶肉结构的变化，从而降低了叶片内二氧化碳扩散的传导性。碳代谢的能力最终会降低，但这是在二氧化碳扩散的传导性大幅降低之后发生的。
Spinach (Spinacia oleracea L.) leaves stressed by irrigation with water containing 1% (w/v) NaCl for 20 days had low conductance to CO2 diffusion both at the stomata and in the mesophyll. Mesophyll anatomy changed in salt-stressed leaves, which could have accounted for the decreased mesophyll conductance. Ribulose 1,5-bisphosphate carboxylase/oxygenase in vitro activity and content were not affected by up to 20 days exposure to salinity but decreased when leaves were exposed to salt stress for longer than 20 days. Salt accumulation also caused a drop of Ca and Mg which might have decreased membrane stability and chlorophyll content, respectively. Measurements of chlorophyll fluorescence indicated that the 20-day-long salt stress did not directly affect photochemistry. We conclude that salinity reduces photosynthesis primarily by reducing the diffusion of CO2 to the chloroplast, both by stomatal closure and by changes in mesophyll structure which decreases the conductance to CO2 diffusion within the leaf. The capacity for carbon metabolism is eventually reduced but that occurs after substantial decreases in the conductance to CO2 diffusion.