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首页> 外文期刊>Journal of Experimental Botany >More than just a vulnerable pipeline: xylem physiology in the light of ion-mediated regulation of plant water transport
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More than just a vulnerable pipeline: xylem physiology in the light of ion-mediated regulation of plant water transport

机译：不仅仅是一条脆弱的管道：离子介导的植物水运输调节作用下的木质部生理

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Major restrictions to the hydraulic conductance of xylem (KXYL) in vascular plants have traditionally been attributed to anatomical constraints. More recently, changes in the cationic concentration of xylem sap have been suggested to be responsible for short-term changes in KXYL based on data for 35 dicot species, and very few gymnosperms and ferns, indicating that xylem water transport may no longer be considered as an entirely passive process. Recent studies have revealed that this so-called ionic effect: (i) varies from little or no increase to >30%, (ii) is species specific, (iii) changes on a seasonal basis, (iv) depends on the cationic concentration, (v) is enhanced in embolized stems, and (vi) is positively correlated with vessel grouping. Furthermore, the ionic effect has been suggested to play functional roles in planta with respect to: (i) phloem-mediated control of xylem hydraulic properties, (ii) compensation of cavitation-induced loss of hydraulic conductance, with the result of optimizing light and water utilization, and (iii) differential regulation of water delivery to branches exposed to different levels of light. Pits are likely to play a key role in the ionic effect, which has largely been explained as a consequence of the poly-electrolytic nature and hydrogel properties of the pectic matrix of interconduit pit membranes, despite little evidence that pit membrane pectins remain present after cell hydrolysis. More research is needed to address the ionic effect in more species, physico-chemical properties of pit membranes, and how the ionic effect may increase xylem hydraulic conductance ‘on demand’.
机译：传统上，维管植物木质部（K XYL ）的水力传导的主要限制是由于解剖学上的限制。最近，基于35个双子叶植物物种和极少裸子植物和蕨类植物的数据，已提出木质部汁液阳离子浓度的变化是造成K XYL 短期变化的原因。水运输可能不再被视为完全被动的过程。最近的研究表明，这种所谓的离子效应：（i）从几乎不增加或不增加到> 30％，（ii）是特定于物种的，（iii）随季节变化，（iv）取决于阳离子浓度，（v）在栓塞茎中得到增强，（vi）与血管分组呈正相关。此外，已提出离子效应在植物中可发挥以下作用：（i）韧皮部介导的木质部水力特性控制，（ii）补偿气蚀引起的水力传导损失，从而优化了光和水分利用；以及（iii）对暴露于不同光照水平的分支机构的水分输送进行不同的调节。坑可能在离子效应中起关键作用，尽管几乎没有证据表明细胞后坑膜果胶仍然存在，但坑在离子效应中可能起关键作用，这主要是由于导管间坑膜的果胶基质的聚电解性质和水凝胶特性所致。水解。需要进行更多的研究来解决更多物种中的离子效应，凹膜的理化特性，以及离子效应如何“按需”增加木质部水力传导率。

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