TY  - JOUR
AU  - Metzner, R.
AU  - Schneider, H. U.
AU  - Breuer, U.
AU  - Thorpe, M.R.
AU  - Schurr, U.
AU  - Schröder, W. H.
TI  - Tracing cationic nutrients from xylem into stem tissue of Phaseolus vulgaris by stable isotope tracers and cryo-secondary ion mass spectrometry
JO  - Plant physiology
VL  - 152
SN  - 0032-0889
CY  - Rockville, Md.: Soc.
PB  - JSTOR
M1  - PreJuSER-6761
SP  - 1030 - 1043
PY  - 2010
N1  - Record converted from VDB: 12.11.2012
AB  - Fluxes of mineral nutrients in the xylem are strongly influenced by interactions with the surrounding stem tissues and are probably regulated by them. Toward a mechanistic understanding of these interactions, we applied stable isotope tracers of magnesium, potassium, and calcium continuously to the transpiration stream of cut bean (Phaseolus vulgaris) shoots to study their radial exchange at the cell and tissue level with stem tissues between pith and phloem. For isotope localization, we combined sample preparation with secondary ion mass spectrometry in a completely cryogenic workflow. After 20 min of application, tracers were readily detectable to various degrees in all tissues. The xylem parenchyma near the vessels exchanged freely with the vessels, its nutrient elements reaching a steady state of strong exchange with elements in the vessels within 20 min, mainly via apoplastic pathways. A slow exchange between vessels and cambium and phloem suggested that they are separated from the xylem, parenchyma, and pith, possibly by an apoplastic barrier to diffusion for nutrients (as for carbohydrates). There was little difference in these distributions when tracers were applied directly to intact xylem via a microcapillary, suggesting that xylem tension had little effect on radial exchange of these nutrients and that their movement was mainly diffusive.
KW  - Biological Transport
KW  - Cryoelectron Microscopy
KW  - Isotopes: chemistry
KW  - Microscopy, Electron, Scanning
KW  - Phaseolus: chemistry
KW  - Plant Stems: ultrastructure
KW  - Plant Transpiration
KW  - Spectrometry, Mass, Secondary Ion: methods
KW  - Xylem: chemistry
KW  - Isotopes (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:19965970
C2  - pmc:PMC2815875
UR  - <Go to ISI:>//WOS:000274246600052
DO  - DOI:10.1104/pp.109.143776
UR  - https://juser.fz-juelich.de/record/6761
ER  -