Imaging salt uptake dynamics in plants using PET

Imaging salt uptake dynamics in plants

Soil salinity is a global environmental challenge for crop production. Understanding the uptake and
transport properties of salt in plants is crucial to evaluate their potential for growth in high salinity soils
and as a basis for engineering varieties with increased salt tolerance. Positron emission tomography
(PET), traditionally used in medical and animal imaging applications for assessing and quantifying the
dynamic bio-distribution of molecular species, has the potential to provide useful measurements of
salt transport dynamics in an intact plant. Here we report on the feasibility of studying the dynamic
transport of 22Na in millet using PET.

Current techniques tend to focus on the cellular basis of transport and there is much still to learn about sodium fluxes and regulation at the level of the whole plant. To better understand how sodium is distributed and regulated within whole organs and the whole plant, the development of novel methods to visualize and quantify sodium transport throughout entire intact plants would be a significant advance.

In this paper, we build on the promising work by considering the dynamic transport of 22Na in plants over a 2-week period using a high-resolution full-ring PET system for 3D imaging. We hypothesize that dynamic PET imaging of sodium over physiologically relevant timescales using the long half-life 22Na radioisotope has the potential to reveal important aspects of macroscopic sodium transport in intact plants which corroborate and build on observations obtained using other methods. Moreover, Our PET analysis of the two green foxtail varieties was cross-validated against conventional measurements of Na+ content and the expression of NHX transcript, a gene implicated in sodium transport.
Our results clearly demonstrate the utility of PET for observing and quantifying dynamic sodium transport in intact plants over a 2-week period.
In conclusion, this study shows that PET is a useful complement to existing techniques for understanding sodium transport and regulatory mechanisms in plants and that it may provide a useful screening tool for research in this area.