Thomas C Pesacreta1,2, Karl H Hasenstein3. 1. Biology Department, University of Louisiana, PO Box 43602, Lafayette, LA, 70504, USA. tcp9769@louisiana.edu. 2. Microscopy Center, University of Louisiana, PO Box 43602, Lafayette, LA, 70504, USA. tcp9769@louisiana.edu. 3. Biology Department, University of Louisiana, PO Box 43602, Lafayette, LA, 70504, USA.
Abstract
MAIN CONCLUSION: Potassium (K), phosphorous (P), and carboxyfluorescein (CF) accumulate in functionally distinct tissues within the pine seedling root cortex. Seedlings of Pinus pinea translocate exogenous CF and endogenous K and P from the female gametophyte/cotyledons to the growing radicle. Following unloading in the root tip, these materials accumulate in characteristic spatial patterns. Transverse sections of root tips show high levels of P in a circular ring of several layers of inner cortical cells. K and CF are minimal in the high P tissue. In contrast, high levels of K and CF accumulate in outer cortical cells, and in the vascular cylinder. These patterns are a property of living tissue because they change after freeze-thaw treatment, which kills the cells and results in uniform distribution of K and P. K concentration can be reduced to undetectable levels by incubation of roots in 100 mM NaCl. Inductively coupled plasma optical emission spectrometry (ICP-OES) analysis and scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) of root segments both reliably determine K and P concentrations.
MAIN CONCLUSION: Potassium (K), phosphorous (P), and carboxyfluorescein (CF) accumulate in functionally distinct tissues within the pine seedling root cortex. Seedlings of Pinus pinea translocate exogenous CF and endogenous K and P from the female gametophyte/cotyledons to the growing radicle. Following unloading in the root tip, these materials accumulate in characteristic spatial patterns. Transverse sections of root tips show high levels of P in a circular ring of several layers of inner cortical cells. K and CF are minimal in the high P tissue. In contrast, high levels of K and CF accumulate in outer cortical cells, and in the vascular cylinder. These patterns are a property of living tissue because they change after freeze-thaw treatment, which kills the cells and results in uniform distribution of K and P. K concentration can be reduced to undetectable levels by incubation of roots in 100 mM NaCl. Inductively coupled plasma optical emission spectrometry (ICP-OES) analysis and scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) of root segments both reliably determine K and P concentrations.
Entities:
Keywords:
ICP-OES; Ion distribution; Mineral distribution; Pinus pinea; Roots; SEM/EDS
Authors: R Viola; A G Roberts; S Haupt; S Gazzani; R D Hancock; N Marmiroli; G C Machray; K J Oparka Journal: Plant Cell Date: 2001-02 Impact factor: 11.277