Short-term salt stress strongly affects dynamic photosynthesis, but not steady-state photosynthesis, in tomato (Solanum lycopersicum)
Short-term salt stress strongly affects dynamic photosynthesis, but not steady-state photosynthesis, in tomato (Solanum lycopersicum)
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DOI：
10.1016/j.envexpbot.2018.02.014
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发表时间：
2018-05
影响因子：
5.7
通讯作者：
Yuqi Zhang;E. Kaiser;Yating Zhang;Qichang Yang;Tao Li
中科院分区：
文献类型：
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作者：
Yuqi Zhang;E. Kaiser;Yating Zhang;Qichang Yang;Tao Li
由于广泛的土壤盐渍化，盐胁迫在世界范围内发生。此外，植物经常受到阳光和阴影的快速交替（晒斑）。尽管盐胁迫和晒斑共同发生，但在盐胁迫下对晒斑的动态光合反应尚不清楚。本研究通过探索光合气体交换和叶绿素荧光，解决了这一差异，在暗-光转换和人工光波动（光斑和暗斑）期间，盐胁迫叶片。3周龄的室内生长番茄（Solanum lycopersicumMill ' Beijing Cherry tomato '）植株分别暴露于0、70或140 mM氯化钠（NaCl）中7-9 天。在盐胁迫下，暗-光过渡后的光合诱导受到强烈抑制，这是由于瞬态气孔限制增加和Rubisco表观活化减慢。在光合诱导过程中，非光化学猝灭（NPQ）和内在水分利用效率（WUEi）与[NaCl]呈正相关。在弱光期（暗斑期），暗斑期持续时间越长，盐胁迫对再照后光合作用的下调越强烈，且这种下调与盐胁迫的严重程度呈正相关。在常规光照条件下，盐胁迫使光合作用降低了12-42%，这主要是由于气孔导度降低所致。盐胁迫下叶片气孔孔面积和气孔指数均显著降低。至关重要的是，盐胁迫对稳态光合能力没有影响，这与光合作用的光响应曲线和co2响应曲线相似。因此，短期盐胁迫对番茄叶片动态光合作用的影响较大，而对稳态光合作用的影响可以忽略不计。
Salt stress occurs worldwide due to widespread soil salinization. Also, plants are often subjected to rapidly alternating periods of sun and shade (sunflecks). Despite this combined occurrence of salt stress and sunflecks, dynamic photosynthetic responses to sunflecks under salt stress remain unknown. This study addresses this discrepancy by exploring photosynthetic gas exchange and chlorophyll fluorescence, both after dark-light transitions and during artificial light fluctuations (lightflecks and shadeflecks), in salt stressed leaves. Three weeks old growth-chamber grown tomato (Solanum lycopersicumMill ‘Beijing Cherry Tomato’) plants were exposed to 0, 70 or 140 mM of sodium chloride (NaCl), for 7–9 days. Photosynthetic induction after dark-light transitions was strongly inhibited in salt-stressed leaves, due to increased transient stomatal limitation and slower apparent Rubisco activation. During photosynthetic induction, non-photochemical quenching (NPQ) and intrinsic water use efficiency (WUEi) were positively correlated with [NaCl]. Under periods of low light (shadeflecks), the longer the shadefleck lasted, the more strongly photosynthesis after re-illumination was downregulated by salt stress, and this downregulation in photosynthesis was positively correlated with the severity of salt stress. Under regularly applied lightflecks, salt stress decreased photosynthesis by 12–42%, which was mainly caused by decreased stomatal conductance. Salt-stressed leaves also displayed significantly lower stomatal pore area and stomatal index. Crucially, salt stress did not affect steady-state photosynthetic capacity as indicated by similar light and CO2response curves of photosynthesis. We conclude that a short-term salt stress strongly affects dynamic leaf photosynthesis in tomato while its effect on steady state photosynthesis is negligible.