Quantification of Sodium Accumulation in Arabidopsis thaliana Using Inductively Coupled Plasma Optical Emission Spectrometery (ICP-OES)

Abstract

Salt stress is a major issue for plants growing in both natural and agricultural settings (Deinlein et al., 2014). For example, irrigation can lead to the build up of salts in the soil as the irrigation water evaporates, leading to salinization, inhibition of plant growth, reduced productivity and eventually to loss of agriculturally usable land. One key element in trying to understand how salt stress impacts plant growth and development, in defining plant salt sensing and response mechanisms and eventually in the breeding or engineering of plants resistant to this stress is monitoring their salt uptake and redistribution. Methods such as imaging Na-sensitive fluorescent probes (Kader and Lindberg, 2005) and use of Na-ion selective microelectrodes (Shabala et al., 2005) offer the potential to follow Na levels in the plant in a non-destructive manner but are technically demanding and not applicable to field, or even many laboratory, conditions. However, tissue sampling followed by inductively coupled plasma spectroscopy (ICP) represents a simple, quantitative assay to monitor total Na levels in plant samples. ICP analysis is also applicable to plants in any environment where samples can be harvested. The approach uses tissue digestion in acid solutions, followed by injection of the resulting sample into an inductively coupled plasma spectrometer and monitoring the characteristic emitted spectrum from Na. As Na is stable, no complex sample preservation is required. Care needs to be taken with possible Na contamination in standards and samples from the water used for sample preparation and from glassware but otherwise, the approach is simple and robust.