TY  - JOUR
AU  - Windt, C. W.
AU  - Gerkema, E.
AU  - Van As, H.
TI  - Most Water in the Tomato Truss Is Imported through the Xylem, Not the Phloem: A Nuclear Magnetic Resonance Flow Imaging Study
JO  - Plant physiology
VL  - 151
SN  - 0032-0889
CY  - Rockville, Md.: Soc.
PB  - JSTOR
M1  - PreJuSER-5901
SP  - 830 - 842
PY  - 2009
N1  - Record converted from VDB: 12.11.2012
AB  - In this study, we demonstrate nuclear magnetic resonance flow imaging of xylem and phloem transport toward a developing tomato (Solanum lycopersicum) truss. During an 8-week period of growth, we measured phloem and xylem fluxes in the truss stalk, aiming to distinguish the contributions of the two transport tissues and draw up a balance between influx and efflux. It is commonly estimated that about 90% of the water reaches the fruit by the phloem and the remaining 10% by the xylem. The xylem is thought to become dysfunctional at an early stage of fruit development. However, our results do not corroborate these findings. On the contrary, we found that xylem transport into the truss remained functional throughout the 8 weeks of growth. During that time, at least 75% of the net influx into the fruit occurred through the external xylem and about 25% via the perimedullary region, which contains both phloem and xylem. About one-half of the net influx was lost due to evaporation. Halfway through truss development, a xylem backflow appeared. As the truss matured, the percentage of xylem water that circulated into the truss and out again increased in comparison with the net uptake, but no net loss of water from the truss was observed. The circulation of xylem water continued even after the fruits and pedicels were removed. This indicates that neither of them was involved in generating or conducting the circulation of sap. Only when the main axis of the peduncle was cut back did the circulation stop.
KW  - Biological Transport
KW  - Lycopersicon esculentum: growth & development
KW  - Lycopersicon esculentum: physiology
KW  - Magnetic Resonance Spectroscopy
KW  - Phloem: physiology
KW  - Rheology: methods
KW  - Water: physiology
KW  - Xylem: physiology
KW  - Water (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:19710234
C2  - pmc:PMC2754649
UR  - <Go to ISI:>//WOS:000270389500028
DO  - DOI:10.1104/pp.109.141044
UR  - https://juser.fz-juelich.de/record/5901
ER  -