期刊
JOURNAL OF THE ROYAL SOCIETY INTERFACE
卷 10, 期 83, 页码 -出版社
ROYAL SOC
DOI: 10.1098/rsif.2013.0055
关键词
phloem transport; sugar translocation; optimal concentration theory
资金
- NSF [1021779]
- Materials Research Science and Engineering Center (MRSEC) at Harvard University [DMR-0820484]
- Direct For Biological Sciences
- Division Of Integrative Organismal Systems [1021779] Funding Source: National Science Foundation
Vascular plants transport energy in the form of sugars from the leaves where they are produced to sites of active growth. The mass flow of sugars through the phloem vascular system is determined by the sap flow rate and the sugar concentration. If the concentration is low, little energy is transferred from source to sink. If it is too high, sap viscosity impedes flow. An interesting question is therefore at which concentration is the sugar flow optimal. Optimization of sugar flow and transport efficiency predicts optimal concentrations of 23.5 per cent (if the pressure differential driving the flow is independent of concentration) and 34.5 per cent (if the pressure is proportional to concentration). Data from more than 50 experiments (41 species) collected from the literature show an average concentration in the range from 18.2 per cent (all species) to 21.1 per cent (active loaders), suggesting that the phloem vasculature is optimized for efficient transport at constant pressure and that active phloem loading may have developed to increase transport efficiency.
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