Slower phloem transport in gymnosperm trees can be attributed to higher sieve element resistance
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Slower phloem transport in gymnosperm trees can be attributed to higher sieve element resistance. / Liesche, Johannes; Windt, Carel; Bohr, Tomas; Schulz, Alexander; Jensen, Kaare.
In: Tree Physiology, Vol. 35, No. 4, 2015, p. 376-386.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Slower phloem transport in gymnosperm trees can be attributed to higher sieve element resistance
AU - Liesche, Johannes
AU - Windt, Carel
AU - Bohr, Tomas
AU - Schulz, Alexander
AU - Jensen, Kaare
PY - 2015
Y1 - 2015
N2 - In trees, carbohydrates produced in photosynthesizing leaves are transported to roots and other sink organs over distances of up to 100 m inside a specialized transport tissue, the phloem. Angiosperm and gymnosperm trees have a fundamentally different phloem anatomy with respect to cell size, shape and connectivity. Whether these differences have an effect on the physiology of carbohydrate transport, however, is not clear. A meta-analysis of the experimental data on phloem transport speed in trees yielded average speeds of 56 cm h-1 for angiosperm trees and 22 cm h-1 for gymnosperm trees. Similar values resulted from theoretical modelling using a simple transport resistance model. Analysis of the model parameters clearly identified sieve element anatomy as the main factor for the significantly slower carbohydrate transport speed inside the phloem in gymnosperm compared to angiosperm trees.In order to investigate the influence of sieve element anatomy on the hydraulic resistance, anatomical data on sieve elements and sieve pores were collected by transmission electron microscopy analysis and from the literature for 18 tree species. Calculations showed that the hydraulic resistance is significantly higher in the gymnosperm than in angiosperm trees. The higher resistance is only partially offset by the considerably longer sieve elements of gymnosperms.
AB - In trees, carbohydrates produced in photosynthesizing leaves are transported to roots and other sink organs over distances of up to 100 m inside a specialized transport tissue, the phloem. Angiosperm and gymnosperm trees have a fundamentally different phloem anatomy with respect to cell size, shape and connectivity. Whether these differences have an effect on the physiology of carbohydrate transport, however, is not clear. A meta-analysis of the experimental data on phloem transport speed in trees yielded average speeds of 56 cm h-1 for angiosperm trees and 22 cm h-1 for gymnosperm trees. Similar values resulted from theoretical modelling using a simple transport resistance model. Analysis of the model parameters clearly identified sieve element anatomy as the main factor for the significantly slower carbohydrate transport speed inside the phloem in gymnosperm compared to angiosperm trees.In order to investigate the influence of sieve element anatomy on the hydraulic resistance, anatomical data on sieve elements and sieve pores were collected by transmission electron microscopy analysis and from the literature for 18 tree species. Calculations showed that the hydraulic resistance is significantly higher in the gymnosperm than in angiosperm trees. The higher resistance is only partially offset by the considerably longer sieve elements of gymnosperms.
U2 - 10.1093/treephys/tpv020
DO - 10.1093/treephys/tpv020
M3 - Journal article
VL - 35
SP - 376
EP - 386
JO - Tree Physiology
JF - Tree Physiology
SN - 0829-318X
IS - 4
ER -
ID: 131165058