Subcellular compartmentation of elements in non‐mycorrhizal and mycorrhizal roots of Pinus sylvestris: an X‐ray microanalytical study. II. The distribution of calcium, potassium and sodium

Abstract

The inter‐ and intracellular distribution of the elements calcium, potassium and sodium in non‐mycorrhizal and mycorrhizal roots of Pinus sylvestris dependent on different external nutrient supply conditions was detected by energy‐dispersive X‐ray microanalysis after cryofixation, freeze‐drying and pressure infiltration of the material. In non‐mycorrhizal and mycorrhizal roots, calcium was mainly detectable in the apoplastic regions. The levels in vacuoles and cytoplasm were near the limits of detection by X‐ray microanalysis. Incubation with high concentrations of potassium and sodium, or mycorrhizal infection with Suillus bovinus and Pisolithus tinctorius reduced the amounts of calcium detectable in the roots, especially in the apoplast of cortical cells. The studies revealed that: potassium is mainly localized in cytoplasm and cell walls; the cytoplasmic content is regulated over a wide range of external potassium concentrations; potassium levels in the inner parts of roots are higher than in the outer parts. Mycorrhizal infection with Suillus bovinus had no effect on the inter‐ and intracellular distribution of potassium in roots but, if the external supply was low, the potassium content in shoots was reduced. In non‐mycorrhizal pine roots and those infected with Paxillus involutus an increase in the sodium content of all cell compartments was observed after treatment with high external concentrations of NaH2PO4. However, an increase in sodium content in mycorrhizas of S. bovinus was not detected. The X‐ray microanalytical results are discussed in relation to the apoplastic movement of nutrients in non‐mycorrhizal and mycorrhizal fine roots of pine and to the demand for these nutrients in different intracellular compartments.

A pH signaling mechanism involved in the spatial distribution of calcium and anion fluxes in ectomycorrhizal roots

“…For example, in the root cortex almost 100% of the cell wall calcium can be easily exchanged for an external 44 Ca label (Peterson & Enstone, 1996; Kuhn et al ., 2000). Similarly, studies of nutrient mobilization in ECM symbiosis have been performed by radioisotope coupling with laser microprobe mass analysis (LAMMA), energy‐dispersive X‐ray spectroscopy (EDXS) and secondary ion mass spectroscopy (SIMS) (Peterson & Enstone, 1996; Bücking & Heyser, 2000; Bücking et al ., 2007). However, very few detailed studies aiming to determine the regulation of ion dynamics in ECM symbiosis have been carried out.…”

Freeze‐dried and resin‐embedded biological material is well suited for ultrastructure research

“…Recent promising results obtained with freeze‐dried embedded material and the different available microanalytical techniques have been published (e.g. Burns & File, 1986; Grohovaz et al ., 1996; Pezzati et al ., 1997; Bücking et al ., 1998, 2000; Neelissen et al ., 1999; Bücking & Heyser, 2000, 2001). In the future, SIMS will become probably the most powerful technique for the microanalytical investigation of freeze‐dried embedded material.…”

ICP-AES analysis in sesame on the root rot disease incidence

“…The roots are severely affected and discolouration of roots follows attack by microorganisms (Singh and Singh 2003). The effect of a fungal infection on the apoplastic Ca content of cortical cells may possibly be due to a change in the cell wall composition of plants (Bucking and Heyser 2000). Calcium is found to vary from 59 ppm to 76 ppm and 43 ppm to 55 ppm at root rot disease and healthy roots in all treatments.…”