Linking phloem function to structure: Analysis with a coupled xylem-phloem transport model
Linking phloem function to structure: Analysis with a coupled xylem-phloem transport model
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DOI：
10.1016/j.jtbi.2009.03.039
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发表时间：
2009-07-21
影响因子：
2
通讯作者：
Nikinmaa, E.
中科院分区：
文献类型：
--
作者：
Holtta, T.;Mencuccini, M.;Nikinmaa, E.
基于Munch假说，建立了木质部-韧皮部耦合运输模型，对韧皮部运输进行了理论分析。结果表明，韧皮部的最大糖运输速率受溶液粘度的限制，运输要求强烈地受当时的木质部水势的影响。分别计算了维持蒸腾作用和同化作用所需的木质部和韧皮部导管的最小数量。在其最大的糖运输速率，韧皮部的功能与高膨压差之间的糖源和汇，但膨压差减少，如果额外的平行管道添加或溶质继电器引入。溶质传递被证明可以减少韧皮部运输所需的平行筛管的数量，从而导致更均匀的膨压，并允许韧皮部内更快的信息传递。由于木质部水势影响木质部和韧皮部的运输，这两个系统的电导被发现耦合，从而在木质部的大的结构投资减少了在韧皮部的投资，反之亦然。(C)2009爱思唯尔有限公司版权所有。
We carried out a theoretical analysis of phloem transport based on Munch hypothesis by developing a coupled xylem-phloem transport model. Results showed that the maximum sugar transport rate of the phloem was limited by solution viscosity and that transport requirements were strongly affected by prevailing xylem water potential. The minimum number of xylem and phloem conduits required to sustain transpiration and assimilation, respectively, were calculated. At its maximum sugar transport rate, the phloem functioned with a high turgor pressure difference between the sugar sources and sinks but the turgor pressure difference was reduced if additional parallel conduits were added or solute relays were introduced. Solute relays were shown to decrease the number of parallel sieve tubes needed for phloem transport, leading to a more uniform turgor pressure and allowing faster information transmission within the phloem. Because xylem water potential affected both xylem and phloem transport, the conductance of the two systems was found to be coupled such that large structural investments in the xylem reduced the need for investment in the phloem and vice versa. (C) 2009 Elsevier Ltd. All rights reserved.