Shifting access to pools of shoot water sustains gas exchange and increases stem hydraulic safety during seasonal atmospheric drought
Shifting access to pools of shoot water sustains gas exchange and increases stem hydraulic safety during seasonal atmospheric drought
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DOI：
10.1111/pce.14080
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发表时间：
2021-05-25
影响因子：
7.3
通讯作者：
Ball, Marilyn C.
中科院分区：
文献类型：
--
作者：
Bryant, Callum;Fuenzalida, Tomas, I;Ball, Marilyn C.
了解植物如何适应干旱对于预测未来的脆弱性至关重要，但提高树木耐旱性的性状的季节性适应仍然没有得到很好的解决。我们假设，旱季驯化的叶和茎性状影响拍摄水存储和水力电容将减轻干旱相关的风险，减少气体交换和液压故障的红树林海桑alba。到了旱季后期，叶片内以及叶片和茎之间的储存水的可用性发生了变化。在整个地上部电容保持稳定的情况下，叶水共质体含量增加了86%，叶电容增加了104%，茎电容下降了80%。尽管植物水势下降，叶和全株导水率保持不变，中午同化率增加。此外，有效叶水之间的最低水势观察到的和相应的茎导损失50%增加了111%。在器官内部和器官之间转移水的可用性，保持叶片水可用于缓冲光合作用增加和茎导水率损失的时期，减轻大气干旱期间碳耗竭和水力失效的风险。获得组织和器官水分的季节性变化可能在干旱适应和避免中起重要作用。
Understanding how plants acclimate to drought is crucial for predicting future vulnerability, yet seasonal acclimation of traits that improve drought tolerance in trees remains poorly resolved. We hypothesized that dry season acclimation of leaf and stem traits influencing shoot water storage and hydraulic capacitance would mitigate the drought-associated risks of reduced gas exchange and hydraulic failure in the mangrove Sonneratia alba. By late dry season, availability of stored water had shifted within leaves and between leaves and stems. While whole shoot capacitance remained stable, the symplastic fraction of leaf water increased 86%, leaf capacitance increased 104% and stem capacitance declined 80%. Despite declining plant water potentials, leaf and whole plant hydraulic conductance remained unchanged, and midday assimilation rates increased. Further, the available leaf water between the minimum water potential observed and that corresponding to 50% loss of stem conductance increased 111%. Shifting availability of pools of water, within and between organs, maintained leaf water available to buffer periods of increased photosynthesis and losses in stem hydraulic conductivity, mitigating risks of carbon depletion and hydraulic failure during atmospheric drought. Seasonal changes in access to tissue and organ water may have an important role in drought acclimation and avoidance.