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Localized stem chilling alters carbon processes in the adjacent stem and in source leaves

Veerle De Schepper UGent, Lynn Vanhaecke UGent and Kathy Steppe UGent (2011) TREE PHYSIOLOGY. 31(11). p.1194-1203
abstract
Transport phloem is no longer associated with impermeable pipes, but is instead considered as a leaky system in which loss and retrieval mechanisms occur. Local stem chilling is often used to study these phenomena. In this study, 5-cm- lengths of stems of 3-year-old oak trees (Quercus robur L.) were locally chilled for 1 week to investigate whether observations at stem and leaf level can be explained by the leakage-retrieval mechanism. The chilling experiment was repeated three times across the growing season. Measurements were made of leaf photosynthesis, carbohydrate concentrations in leaves and bark, stem growth and maximum daily stem shrinkage. Across the growing season, a feedback inhibition in leaf photosynthesis was observed, causing increased dark respiration and starch concentration. This inhibition was attributed to the total phloem resistance which locally increased due to the cold temperatures. It is hypothesized that this higher phloem resistance increased the phloem pressure above the cold block up to the source leaves, inducing feedback inhibition. In addition, an increase in radial stem growth and carbohydrate concentration was observed above the cold block, while the opposite occurred below the block. These observations indicate that net lateral leakage of carbohydrates from the phloem was enhanced above the cold block and that translocation towards regions below the block decreased. This behaviour is probably also attributable to the higher phloem resistance. The chilling effects on radial stem growth and carbohydrate concentration were significant in the middle of the growing season, while they were not at the beginning and near the end of the growing season. Furthermore, maximum daily shrinkages were larger above the cold block during all chilling experiments, indicating an increased resistance in the xylem vessels, also generated by low temperatures. In conclusion, localized stem chilling altered multiple carbon processes in the source leaves and the main stem by changing hydraulic resistances.
Please use this url to cite or link to this publication:
author
organization
year
type
journalArticle (original)
publication status
published
subject
keyword
sugar transport, translocation, stem growth, Quercus robur L, seasonal variation, phloem, feedback inhibition of photosynthesis, cold girdling, carbohydrates, DIAMETER VARIATIONS, PHLOEM TRANSPORT, TRUNK SHRINKAGE, STORAGE MODEL, WATER-FLOW, PINE TREES, SINK, PHOTOSYNTHESIS, CARBOHYDRATE, ASSIMILATE
journal title
TREE PHYSIOLOGY
Tree Physiol.
volume
31
issue
11
pages
1194 - 1203
Web of Science type
Article
Web of Science id
000297223100005
JCR category
FORESTRY
JCR impact factor
2.876 (2011)
JCR rank
2/59 (2011)
JCR quartile
1 (2011)
ISSN
0829-318X
DOI
10.1093/treephys/tpr099
language
English
UGent publication?
yes
classification
A1
copyright statement
I have transferred the copyright for this publication to the publisher
id
2135514
handle
http://hdl.handle.net/1854/LU-2135514
date created
2012-06-07 10:09:27
date last changed
2012-06-20 15:56:49
@article{2135514,
  abstract     = {Transport phloem is no longer associated with impermeable pipes, but is instead considered as a leaky system in which loss and retrieval mechanisms occur. Local stem chilling is often used to study these phenomena. In this study, 5-cm- lengths of stems of 3-year-old oak trees (Quercus robur L.) were locally chilled for 1 week to investigate whether observations at stem and leaf level can be explained by the leakage-retrieval mechanism. The chilling experiment was repeated three times across the growing season. Measurements were made of leaf photosynthesis, carbohydrate concentrations in leaves and bark, stem growth and maximum daily stem shrinkage. Across the growing season, a feedback inhibition in leaf photosynthesis was observed, causing increased dark respiration and starch concentration. This inhibition was attributed to the total phloem resistance which locally increased due to the cold temperatures. It is hypothesized that this higher phloem resistance increased the phloem pressure above the cold block up to the source leaves, inducing feedback inhibition. In addition, an increase in radial stem growth and carbohydrate concentration was observed above the cold block, while the opposite occurred below the block. These observations indicate that net lateral leakage of carbohydrates from the phloem was enhanced above the cold block and that translocation towards regions below the block decreased. This behaviour is probably also attributable to the higher phloem resistance. The chilling effects on radial stem growth and carbohydrate concentration were significant in the middle of the growing season, while they were not at the beginning and near the end of the growing season. Furthermore, maximum daily shrinkages were larger above the cold block during all chilling experiments, indicating an increased resistance in the xylem vessels, also generated by low temperatures. In conclusion, localized stem chilling altered multiple carbon processes in the source leaves and the main stem by changing hydraulic resistances.},
  author       = {De Schepper, Veerle and Vanhaecke, Lynn and Steppe, Kathy},
  issn         = {0829-318X},
  journal      = {TREE PHYSIOLOGY},
  keyword      = {sugar transport,translocation,stem growth,Quercus robur L,seasonal variation,phloem,feedback inhibition of photosynthesis,cold girdling,carbohydrates,DIAMETER VARIATIONS,PHLOEM TRANSPORT,TRUNK SHRINKAGE,STORAGE MODEL,WATER-FLOW,PINE TREES,SINK,PHOTOSYNTHESIS,CARBOHYDRATE,ASSIMILATE},
  language     = {eng},
  number       = {11},
  pages        = {1194--1203},
  title        = {Localized stem chilling alters carbon processes in the adjacent stem and in source leaves},
  url          = {http://dx.doi.org/10.1093/treephys/tpr099},
  volume       = {31},
  year         = {2011},
}

Chicago
De Schepper, Veerle, Lynn Vanhaecke, and Kathy Steppe. 2011. “Localized Stem Chilling Alters Carbon Processes in the Adjacent Stem and in Source Leaves.” Tree Physiology 31 (11): 1194–1203.
APA
De Schepper, V., Vanhaecke, L., & Steppe, K. (2011). Localized stem chilling alters carbon processes in the adjacent stem and in source leaves. TREE PHYSIOLOGY, 31(11), 1194–1203.
Vancouver
1.
De Schepper V, Vanhaecke L, Steppe K. Localized stem chilling alters carbon processes in the adjacent stem and in source leaves. TREE PHYSIOLOGY. 2011;31(11):1194–203.
MLA
De Schepper, Veerle, Lynn Vanhaecke, and Kathy Steppe. “Localized Stem Chilling Alters Carbon Processes in the Adjacent Stem and in Source Leaves.” TREE PHYSIOLOGY 31.11 (2011): 1194–1203. Print.